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speed of light timer

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  • computer50000
    Hi there, I need a device which can measure the fluctuations, in a light ray, with the speed of light. I mean, I need to know if at second 10^-8 (ten to power
    Message 1 of 19 , Oct 31, 2005
      Hi there,

      I need a device which can measure the fluctuations, in a light ray,
      with the speed of light.

      I mean, I need to know if at second 10^-8 (ten to power minus 8) I have
      a fluctuation in a light ray. I'm not interested to compute the power
      of that ray. I'm just interested to know if at a given moment in time
      (very, very small) it was or not a fluctuation in the intensity of that
      ray.

      Is this possible?

      Thanks,
      Michael
    • Stefan Trethan
      On Tue, 01 Nov 2005 07:02:15 +0100, computer50000 ... Well, fast scopes certainly go down there in the nanosecond range. I m not sure about optical receivers,
      Message 2 of 19 , Nov 1, 2005
        On Tue, 01 Nov 2005 07:02:15 +0100, computer50000
        <computer50000@...> wrote:

        > Hi there,
        > I need a device which can measure the fluctuations, in a light ray,
        > with the speed of light.
        > I mean, I need to know if at second 10^-8 (ten to power minus 8) I have
        > a fluctuation in a light ray. I'm not interested to compute the power
        > of that ray. I'm just interested to know if at a given moment in time
        > (very, very small) it was or not a fluctuation in the intensity of that
        > ray.
        > Is this possible?
        > Thanks,
        > Michael


        Well, fast scopes certainly go down there in the nanosecond range.
        I'm not sure about optical receivers, if any diodes are fast enough, but i
        would expect.


        But i don't fully understand what you need. When do you need to measure?
        How do you know when to expect a fluctuation? Is it repetitive or single
        shot?

        In short, what do you want to do?

        As for building something, well, to measure the time with ns accuracy you
        need a timer running at a 1Ghz clock. While that's not insane it is
        slightly out of my homebrew experience.

        Best bet for me seems to be a scope. You need some form of event to
        trigger it when you expect the light fluctutation. Maybe if you use a
        laser beam you can have a diode at the laser, giving you a "start" signal,
        and then the beam goes away to a mirror, and you measure the reflected
        light too. This would give you the distance between laser and mirror *2 on
        the screen. Remember the signals in the coax cables will be somewhat
        slower than speed of light, so you need them short and equal length.


        Need more details to suggest any hardware.


        ST
      • bdl7431
        Hi - Also, the rise time of your detector will play into this - this is the time required for the new signal seen by the detector. If its slower than your
        Message 3 of 19 , Nov 1, 2005
          Hi - Also, the rise time of your detector will play into this - this is the
          time required for the new signal seen by the detector. If its slower than
          your observed phenomea, then I doubt you'll see it, or get much accuracy.

          Just my 0.02 cents/euros worth....

          Bruce
          ----- Original Message -----
          From: "Stefan Trethan" <stefan_trethan@...>
          To: <Electronics_101@yahoogroups.com>
          Sent: Tuesday, November 01, 2005 3:52 AM
          Subject: Re: [Electronics_101] speed of light timer


          > On Tue, 01 Nov 2005 07:02:15 +0100, computer50000
          > <computer50000@...> wrote:
          >
          >> Hi there,
          >> I need a device which can measure the fluctuations, in a light ray,
          >> with the speed of light.
          >> I mean, I need to know if at second 10^-8 (ten to power minus 8) I have
          >> a fluctuation in a light ray. I'm not interested to compute the power
          >> of that ray. I'm just interested to know if at a given moment in time
          >> (very, very small) it was or not a fluctuation in the intensity of that
          >> ray.
          >> Is this possible?
          >> Thanks,
          >> Michael
          >
          >
          > Well, fast scopes certainly go down there in the nanosecond range.
          > I'm not sure about optical receivers, if any diodes are fast enough, but i
          > would expect.
          >
          >
          > But i don't fully understand what you need. When do you need to measure?
          > How do you know when to expect a fluctuation? Is it repetitive or single
          > shot?
          >
          > In short, what do you want to do?
          >
          > As for building something, well, to measure the time with ns accuracy you
          > need a timer running at a 1Ghz clock. While that's not insane it is
          > slightly out of my homebrew experience.
          >
          > Best bet for me seems to be a scope. You need some form of event to
          > trigger it when you expect the light fluctutation. Maybe if you use a
          > laser beam you can have a diode at the laser, giving you a "start" signal,
          > and then the beam goes away to a mirror, and you measure the reflected
          > light too. This would give you the distance between laser and mirror *2 on
          > the screen. Remember the signals in the coax cables will be somewhat
          > slower than speed of light, so you need them short and equal length.
          >
          >
          > Need more details to suggest any hardware.
          >
          >
          > ST
          >
          >
          >
          >
          > Yahoo! Groups Links
          >
          >
          >
          >
          >
          >
          >
        • computer50000
          Dear Stefan, I m sending a light ray with a laser. The ray will follow some complicated path. Sometimes, the ray will be splitted into 2 rays and each of them
          Message 4 of 19 , Nov 1, 2005
            Dear Stefan,

            I'm sending a light ray with a laser. The ray will follow some
            complicated path. Sometimes, the ray will be splitted into 2 rays and
            each of them will follow some path.

            All rays have the same destination, but they will reach there at
            different moments in time (probably), depending on the length of the
            path that they have followed.

            I know the exact moment when a particular ray should get to the
            destination, but I need to know if it actually got there (or it has
            got stuck somewhere on the path).

            This is why I need some device, which can tell me if there is a
            fluctuation in the light, at the destination point, at a given moment
            in time (that moment must be specified with high precision ~ 10^-9).
            If I have a fluctuation in the signat at that moment I know for sure
            that the particular ray which I was expecting has arrived there.

            Thanks,
            Michael


            --- In Electronics_101@yahoogroups.com, "Stefan Trethan"
            <stefan_trethan@g...> wrote:
            >
            > On Tue, 01 Nov 2005 07:02:15 +0100, computer50000
            > <computer50000@y...> wrote:
            >
            > > Hi there,
            > > I need a device which can measure the fluctuations, in a light
            ray,
            > > with the speed of light.
            > > I mean, I need to know if at second 10^-8 (ten to power minus 8)
            I have
            > > a fluctuation in a light ray. I'm not interested to compute the
            power
            > > of that ray. I'm just interested to know if at a given moment in
            time
            > > (very, very small) it was or not a fluctuation in the intensity
            of that
            > > ray.
            > > Is this possible?
            > > Thanks,
            > > Michael
            >
            >
            > Well, fast scopes certainly go down there in the nanosecond range.
            > I'm not sure about optical receivers, if any diodes are fast
            enough, but i
            > would expect.
            >
            >
            > But i don't fully understand what you need. When do you need to
            measure?
            > How do you know when to expect a fluctuation? Is it repetitive or
            single
            > shot?
            >
            > In short, what do you want to do?
            >
            > As for building something, well, to measure the time with ns
            accuracy you
            > need a timer running at a 1Ghz clock. While that's not insane it
            is
            > slightly out of my homebrew experience.
            >
            > Best bet for me seems to be a scope. You need some form of event
            to
            > trigger it when you expect the light fluctutation. Maybe if you use
            a
            > laser beam you can have a diode at the laser, giving you a "start"
            signal,
            > and then the beam goes away to a mirror, and you measure the
            reflected
            > light too. This would give you the distance between laser and
            mirror *2 on
            > the screen. Remember the signals in the coax cables will be
            somewhat
            > slower than speed of light, so you need them short and equal length.
            >
            >
            > Need more details to suggest any hardware.
            >
            >
            > ST
            >
          • Stefan Trethan
            Well, do you need to make this a automated process or can you take manual measurements (look at a scope screen)? I would think that a fast oscilloscope (with
            Message 5 of 19 , Nov 1, 2005
              Well, do you need to make this a automated process or can you take manual
              measurements (look at a scope screen)?

              I would think that a fast oscilloscope (with under 1ns risetime) and a
              optical receiver with a risetime in the same range will be the solution.
              You would need a real-time storage scope if the signal is non-repetitive.
              On the scope screen you would then see pulses, or steps, at the times
              where different beams arrive at the receiver. You would need to use one
              beam to trigger the scope (one which is always arriving before the
              interesting one might come).

              I dunno what your budget is, it can be done in a very expensive manner,
              but probably also in a somewhat cheap manner. Ideally you could repeat the
              process repetitively with the same result, then you wouldn't need real
              time storage, which would make the scope much easier to get or borrow. The
              optical receiver can be bought for $$$$$ or certainly be built much
              cheaper with a fast photodiode. I mean you can get a 1ns rise/fall diode
              at mouser these days, i would expect a even better diode is still
              affordable. Of course you need a bias/amplifier circuit too that is fast
              enough, google finds some.

              Getting a scope with better than 1ns risetime, and single shot capability
              at that, would appear to be the most expensive thing, otoh you can rent
              them and it is certainly easier to find than the photoreceiver.

              ST


              On Tue, 01 Nov 2005 12:38:42 +0100, computer50000
              <computer50000@...> wrote:

              > Dear Stefan,
              > I'm sending a light ray with a laser. The ray will follow some
              > complicated path. Sometimes, the ray will be splitted into 2 rays and
              > each of them will follow some path.
              > All rays have the same destination, but they will reach there at
              > different moments in time (probably), depending on the length of the
              > path that they have followed.
              > I know the exact moment when a particular ray should get to the
              > destination, but I need to know if it actually got there (or it has
              > got stuck somewhere on the path).
              > This is why I need some device, which can tell me if there is a
              > fluctuation in the light, at the destination point, at a given moment
              > in time (that moment must be specified with high precision ~ 10^-9).
              > If I have a fluctuation in the signat at that moment I know for sure
              > that the particular ray which I was expecting has arrived there.
              > Thanks,
              > Michael
            • computer50000
              Thanks Stefan, I just need to know if it was a fluctuation in the intensity of light. Is not important whether I read this manually or by using an computer.
              Message 6 of 19 , Nov 1, 2005
                Thanks Stefan,

                I just need to know if it was a fluctuation in the intensity of
                light. Is not important whether I read this manually or by using an
                computer. However, because the time is very very short probably I
                need to store it. And another reason is that probably there will be
                many, many signals (I mean many fluctuations). But, at a given moment
                I know that there is only one fluctuation.

                The signal is non repetitive.

                The price is not important at this moment. First of all I'm looking
                for a solution and then I will look to the implementation.

                Could you give me some more details on how I use the optical receiver
                and the oscilloscope. I'm a computer scientist which does not know
                too many things about electronics stuff.

                Thanks,



                --- In Electronics_101@yahoogroups.com, "Stefan Trethan"
                <stefan_trethan@g...> wrote:
                >
                > Well, do you need to make this a automated process or can you take
                manual
                > measurements (look at a scope screen)?
                >
                > I would think that a fast oscilloscope (with under 1ns risetime)
                and a
                > optical receiver with a risetime in the same range will be the
                solution.
                > You would need a real-time storage scope if the signal is non-
                repetitive.
                > On the scope screen you would then see pulses, or steps, at the
                times
                > where different beams arrive at the receiver. You would need to use
                one
                > beam to trigger the scope (one which is always arriving before the
                > interesting one might come).
                >
                > I dunno what your budget is, it can be done in a very expensive
                manner,
                > but probably also in a somewhat cheap manner. Ideally you could
                repeat the
                > process repetitively with the same result, then you wouldn't need
                real
                > time storage, which would make the scope much easier to get or
                borrow. The
                > optical receiver can be bought for $$$$$ or certainly be built
                much
                > cheaper with a fast photodiode. I mean you can get a 1ns rise/fall
                diode
                > at mouser these days, i would expect a even better diode is still
                > affordable. Of course you need a bias/amplifier circuit too that is
                fast
                > enough, google finds some.
                >
                > Getting a scope with better than 1ns risetime, and single shot
                capability
                > at that, would appear to be the most expensive thing, otoh you can
                rent
                > them and it is certainly easier to find than the photoreceiver.
                >
                > ST
                >
                >
                > On Tue, 01 Nov 2005 12:38:42 +0100, computer50000
                > <computer50000@y...> wrote:
                >
                > > Dear Stefan,
                > > I'm sending a light ray with a laser. The ray will follow some
                > > complicated path. Sometimes, the ray will be splitted into 2 rays
                and
                > > each of them will follow some path.
                > > All rays have the same destination, but they will reach there at
                > > different moments in time (probably), depending on the length of
                the
                > > path that they have followed.
                > > I know the exact moment when a particular ray should get to the
                > > destination, but I need to know if it actually got there (or it
                has
                > > got stuck somewhere on the path).
                > > This is why I need some device, which can tell me if there is a
                > > fluctuation in the light, at the destination point, at a given
                moment
                > > in time (that moment must be specified with high precision ~ 10^-
                9).
                > > If I have a fluctuation in the signat at that moment I know for
                sure
                > > that the particular ray which I was expecting has arrived there.
                > > Thanks,
                > > Michael
                >
              • Stefan Trethan
                On Tue, 01 Nov 2005 13:51:50 +0100, computer50000 ... You can buy off-the shelf photoreceivers that hook straight to the scope, and a power supply. The scope
                Message 7 of 19 , Nov 1, 2005
                  On Tue, 01 Nov 2005 13:51:50 +0100, computer50000
                  <computer50000@...> wrote:

                  >
                  > The price is not important at this moment. First of all I'm looking
                  > for a solution and then I will look to the implementation.
                  > Could you give me some more details on how I use the optical receiver
                  > and the oscilloscope. I'm a computer scientist which does not know
                  > too many things about electronics stuff.
                  > Thanks,


                  You can buy off-the shelf photoreceivers that hook straight to the scope,
                  and a power supply.

                  The scope could be a digital storage scope with under 1ns risetime, and
                  over 1Gs. That would give resolution in the 10^-9 ballpark. Most scopes
                  can be hooked to a computer, which you can use to document measurements or
                  even use to execute and interpret the measurement automatically.

                  Any optical research/experimentation facility will have such stuff in use,
                  ultrafast optical pulses are the rage right now, so most universities
                  could allow you to see the required gear so you can get a closer idea.


                  ST
                • Dave Mucha
                  ... What about super high speed photography ? I remember seeing a photo of a pulse of light. there was a matrix of mirrors and the photo caught the pulse in
                  Message 8 of 19 , Nov 1, 2005
                    --- In Electronics_101@yahoogroups.com, "computer50000"
                    <computer50000@y...> wrote:
                    >
                    >
                    > Dear Stefan,
                    >
                    > I'm sending a light ray with a laser. The ray will follow some
                    > complicated path. Sometimes, the ray will be splitted into 2 rays and
                    > each of them will follow some path.
                    >
                    > All rays have the same destination, but they will reach there at
                    > different moments in time (probably), depending on the length of the
                    > path that they have followed.
                    >
                    > I know the exact moment when a particular ray should get to the
                    > destination, but I need to know if it actually got there (or it has
                    > got stuck somewhere on the path).
                    >
                    > This is why I need some device, which can tell me if there is a
                    > fluctuation in the light, at the destination point, at a given moment
                    > in time (that moment must be specified with high precision ~ 10^-9).
                    > If I have a fluctuation in the signat at that moment I know for sure
                    > that the particular ray which I was expecting has arrived there.
                    >
                    > Thanks,
                    > Michael

                    What about super high speed photography ?

                    I remember seeing a photo of a pulse of light.

                    there was a matrix of mirrors and the photo caught the pulse in the
                    middle of the matrix as it was bouncing from one to the next.

                    Probably way tooo complex for lab testing, but a great photo for the
                    wow factor.

                    Dave
                  • computer50000
                    Dear Dave, Could you give me some more information on where could I find that picture? Thanks, Michael
                    Message 9 of 19 , Nov 1, 2005
                      Dear Dave,

                      Could you give me some more information on where could I find that
                      picture?

                      Thanks,
                      Michael

                      > What about super high speed photography ?
                      >
                      > I remember seeing a photo of a pulse of light.
                      >
                      > there was a matrix of mirrors and the photo caught the pulse in the
                      > middle of the matrix as it was bouncing from one to the next.
                      >
                      > Probably way tooo complex for lab testing, but a great photo for the
                      > wow factor.
                      >
                      > Dave
                      >
                    • Stefan Trethan
                      On Tue, 01 Nov 2005 16:29:00 +0100, computer50000 ... I would appreciate that too, it must be quite hard to do considering the light has to travel to the
                      Message 10 of 19 , Nov 1, 2005
                        On Tue, 01 Nov 2005 16:29:00 +0100, computer50000
                        <computer50000@...> wrote:

                        > Dear Dave,
                        > Could you give me some more information on where could I find that
                        > picture?
                        > Thanks,
                        > Michael


                        I would appreciate that too, it must be quite hard to do considering the
                        light has to travel to the camera as well.

                        ST
                      • One Two
                        I don t know much about optical equipment, but I have made circuits that detect light intensity. A photodiode, wired in a transresistive mode, can be made to
                        Message 11 of 19 , Nov 1, 2005
                          I don't know much about optical equipment, but I have made circuits that detect light intensity. A photodiode, wired in a transresistive mode, can be made to have incredibly high gains, allowing even the smallest of light changes to be detected. The speed at which the circuit functions will be dependent on the type of op amp you use.

                          computer50000 <computer50000@...> wrote:
                          Hi there,

                          I need a device which can measure the fluctuations, in a light ray,
                          with the speed of light.

                          I mean, I need to know if at second 10^-8 (ten to power minus 8) I have
                          a fluctuation in a light ray. I'm not interested to compute the power
                          of that ray. I'm just interested to know if at a given moment in time
                          (very, very small) it was or not a fluctuation in the intensity of that
                          ray.

                          Is this possible?

                          Thanks,
                          Michael




                        • computer50000
                          I also don t know if the light is the best solution to choose. Right now I m looking for some solutions to my problem. What I know is that I send a signal
                          Message 12 of 19 , Nov 1, 2005
                            I also don't know if the light is the best solution to choose. Right
                            now I'm looking for some solutions to my problem. What I know is that
                            I send a signal (probably a light ray) into some device... the light
                            will be divided into some nodes of the device and because of that I
                            will have multiple rays at the destination. But I know the moment
                            when a particular ray will arrive there. I need only to know whether
                            that particular ray has arrived there (or it was stuck somewhere).

                            Do you think that I could use another kind of signal (instead of
                            light). At a theoretical level I work with signals, but if I want to
                            make an implementation probably (???) the light is the best. Because
                            I need SPEED.

                            Any suggestions are welcomed !

                            Thanks,
                            M

                            --- In Electronics_101@yahoogroups.com, One Two <smjones1969@s...>
                            wrote:
                            >
                            > I don't know much about optical equipment, but I have made circuits
                            that detect light intensity. A photodiode, wired in a transresistive
                            mode, can be made to have incredibly high gains, allowing even the
                            smallest of light changes to be detected. The speed at which the
                            circuit functions will be dependent on the type of op amp you use.
                            >
                            > computer50000 <computer50000@y...> wrote:Hi there,
                            >
                            > I need a device which can measure the fluctuations, in a light ray,
                            > with the speed of light.
                            >
                            > I mean, I need to know if at second 10^-8 (ten to power minus 8) I
                            have
                            > a fluctuation in a light ray. I'm not interested to compute the
                            power
                            > of that ray. I'm just interested to know if at a given moment in
                            time
                            > (very, very small) it was or not a fluctuation in the intensity of
                            that
                            > ray.
                            >
                            > Is this possible?
                            >
                            > Thanks,
                            > Michael
                            >
                            >
                            >
                            >
                            >
                            >
                            > ---------------------------------
                            > YAHOO! GROUPS LINKS
                            >
                            >
                            > Visit your group "Electronics_101" on the web.
                            >
                            > To unsubscribe from this group, send an email to:
                            > Electronics_101-unsubscribe@yahoogroups.com
                            >
                            > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                            Service.
                            >
                            >
                            > ---------------------------------
                            >
                          • Stefan Trethan
                            If the device can be simulated using a electric net i would simply use electric pulses. They propagate only a little bit slower than light, and can be
                            Message 13 of 19 , Nov 1, 2005
                              If the "device" can be simulated using a electric net i would simply use
                              electric pulses.
                              They propagate only a little bit slower than light, and can be measured
                              somewhat easier IMO.
                              You'd create them with a fast pulse generator, and see them with a scope.

                              However it might be tricky to build whatever function you need
                              electrically, especially with limited understanding of HF electronics.

                              Other things such as radio waves, sound, pressure waves, or even materials
                              like a flow of fluid or gas might be possible, but it really depends on
                              what you want to look at.



                              ST



                              On Tue, 01 Nov 2005 18:12:20 +0100, computer50000
                              <computer50000@...> wrote:

                              > I also don't know if the light is the best solution to choose. Right
                              > now I'm looking for some solutions to my problem. What I know is that
                              > I send a signal (probably a light ray) into some device... the light
                              > will be divided into some nodes of the device and because of that I
                              > will have multiple rays at the destination. But I know the moment
                              > when a particular ray will arrive there. I need only to know whether
                              > that particular ray has arrived there (or it was stuck somewhere).
                              > Do you think that I could use another kind of signal (instead of
                              > light). At a theoretical level I work with signals, but if I want to
                              > make an implementation probably (???) the light is the best. Because
                              > I need SPEED.
                              > Any suggestions are welcomed !
                              > Thanks,
                              > M
                            • computer50000
                              Could you give me some more information on using electric pulses? Please keep in mind that speed is a priority in my system. Thanks, M ... simply use ...
                              Message 14 of 19 , Nov 1, 2005
                                Could you give me some more information on using electric pulses?

                                Please keep in mind that speed is a priority in my system.

                                Thanks,
                                M


                                --- In Electronics_101@yahoogroups.com, "Stefan Trethan"
                                <stefan_trethan@g...> wrote:
                                >
                                > If the "device" can be simulated using a electric net i would
                                simply use
                                > electric pulses.
                                > They propagate only a little bit slower than light, and can be
                                measured
                                > somewhat easier IMO.
                                > You'd create them with a fast pulse generator, and see them with a
                                scope.
                                >
                                > However it might be tricky to build whatever function you need
                                > electrically, especially with limited understanding of HF
                                electronics.
                                >
                                > Other things such as radio waves, sound, pressure waves, or even
                                materials
                                > like a flow of fluid or gas might be possible, but it really
                                depends on
                                > what you want to look at.
                                >
                                >
                                >
                                > ST
                                >
                                >
                                >
                                > On Tue, 01 Nov 2005 18:12:20 +0100, computer50000
                                > <computer50000@y...> wrote:
                                >
                                > > I also don't know if the light is the best solution to choose.
                                Right
                                > > now I'm looking for some solutions to my problem. What I know is
                                that
                                > > I send a signal (probably a light ray) into some device... the
                                light
                                > > will be divided into some nodes of the device and because of that
                                I
                                > > will have multiple rays at the destination. But I know the moment
                                > > when a particular ray will arrive there. I need only to know
                                whether
                                > > that particular ray has arrived there (or it was stuck somewhere).
                                > > Do you think that I could use another kind of signal (instead of
                                > > light). At a theoretical level I work with signals, but if I want
                                to
                                > > make an implementation probably (???) the light is the best.
                                Because
                                > > I need SPEED.
                                > > Any suggestions are welcomed !
                                > > Thanks,
                                > > M
                                >
                              • Stefan Trethan
                                On Tue, 01 Nov 2005 18:45:45 +0100, computer50000 ... You send a pulse into a line, it travels along it, imagine it like a water wave. At the ends of the line
                                Message 15 of 19 , Nov 1, 2005
                                  On Tue, 01 Nov 2005 18:45:45 +0100, computer50000
                                  <computer50000@...> wrote:

                                  > Could you give me some more information on using electric pulses?
                                  > Please keep in mind that speed is a priority in my system.
                                  > Thanks,
                                  > M


                                  You send a pulse into a line, it travels along it, imagine it like a water
                                  wave. At the ends of the line it will be reflected unless there's the
                                  right termination resistance.

                                  Not much to it really without going into serious maths which i'm not going
                                  to do. Electric pulses travel in the ballpark of 2E8m/s, i would say that
                                  is plenty fast.

                                  look with google for pulses and transmission line.


                                  ST
                                • Steve
                                  I m curious, are you Michael or Laura? I see the same posts in sci.electronics.design and sci.physics but signed Laura. I mean exactly the same post, word for
                                  Message 16 of 19 , Nov 1, 2005
                                    I'm curious, are you Michael or Laura? I see the same posts in
                                    sci.electronics.design and sci.physics but signed Laura.

                                    I mean exactly the same post, word for word, comma for comma.

                                    Steve Greenfield

                                    --- In Electronics_101@yahoogroups.com, "computer50000"
                                    <computer50000@y...> wrote:
                                    >
                                    > Hi there,
                                    >
                                    > I need a device which can measure the fluctuations, in a light ray,
                                    > with the speed of light.
                                    >
                                    > I mean, I need to know if at second 10^-8 (ten to power minus 8) I have
                                    > a fluctuation in a light ray. I'm not interested to compute the power
                                    > of that ray. I'm just interested to know if at a given moment in time
                                    > (very, very small) it was or not a fluctuation in the intensity of that
                                    > ray.
                                    >
                                    > Is this possible?
                                    >
                                    > Thanks,
                                    > Michael
                                    >
                                  • One Two
                                    Just in case you didn t know, light and the electrical signal propagate at roughly the same speed. I seriously doubt you would need to be concerned in the
                                    Message 17 of 19 , Nov 1, 2005
                                      Just in case you didn't know, light and the electrical signal propagate at roughly the same speed. I seriously doubt you would need to be concerned in the small difference in speed between the two for your application. If you instead use an electrical signal, you will gain the advantages of it staying in the medium and an extreme variety of devices to choose from to work with your signal.

                                      computer50000 <computer50000@...> wrote:
                                      I also don't know if the light is the best solution to choose. Right
                                      now I'm looking for some solutions to my problem. What I know is that
                                      I send a signal (probably a light ray) into some device... the light
                                      will be divided into some nodes of the device and because of that I
                                      will have multiple rays at the destination. But I know the moment
                                      when a particular ray will arrive there. I need only to know whether
                                      that particular ray has arrived there (or it was stuck somewhere).

                                      Do you think that I could use another kind of signal (instead of
                                      light). At a theoretical level I work with signals, but if I want to
                                      make an implementation probably (???) the light is the best. Because
                                      I need SPEED.

                                      Any suggestions are welcomed !

                                      Thanks,
                                      M

                                      --- In Electronics_101@yahoogroups.com, One Two <smjones1969@s...>
                                      wrote:
                                      >
                                      > I don't know much about optical equipment, but I have made circuits
                                      that detect light intensity. A photodiode, wired in a transresistive
                                      mode, can be made to have incredibly high gains, allowing even the
                                      smallest of light changes to be detected. The speed at which the
                                      circuit functions will be dependent on the type of op amp you use.
                                      >
                                      > computer50000 <computer50000@y...> wrote:Hi there,
                                      >
                                      > I need a device which can measure the fluctuations, in a light ray,
                                      > with the speed of light.
                                      >
                                      > I mean, I need to know if at second 10^-8 (ten to power minus 8) I
                                      have
                                      > a fluctuation in a light ray. I'm not interested to compute the
                                      power
                                      > of that ray. I'm just interested to know if at a given moment in
                                      time
                                      > (very, very small) it was or not a fluctuation in the intensity of
                                      that
                                      > ray.
                                      >
                                      > Is this possible?
                                      >
                                      > Thanks,
                                      > Michael
                                      >
                                      >
                                      >
                                      >
                                      >
                                      >
                                      > ---------------------------------
                                      > YAHOO! GROUPS LINKS
                                      >
                                      >
                                      >     Visit your group "Electronics_101" on the web.
                                      >  
                                      >     To unsubscribe from this group, send an email to:
                                      >  Electronics_101-unsubscribe@yahoogroups.com
                                      >  
                                      >     Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                                      Service.
                                      >
                                      >
                                      > ---------------------------------
                                      >





                                    • rtstofer
                                      It is worth checking VOP (velocity of propogation) in any cable or wire you select. It is not unusual for VOP to be around .8 or 80% of the speed of light,
                                      Message 18 of 19 , Nov 2, 2005
                                        It is worth checking VOP (velocity of propogation) in any cable or
                                        wire you select. It is not unusual for VOP to be around .8 or 80%
                                        of the speed of light, maybe even down to 0.7. See
                                        http://www.picwire.com/technical/paper2.html

                                        The VOP in a twisted pair cable might be around 0.65. See
                                        http://www.tscm.com/riprcop.html

                                        At VOP of 0.65, I don't consider that anywhere close to the speed of
                                        light.

                                        Knowing VOP is important in electrical design because signals do not
                                        arrive in zero time. It is not unusual to skew a clock signal by
                                        adding a length of wire to slow it down and realign it with the
                                        data. Consider the multicabinet mainframe computer. Here
                                        realignment is critical.



                                        --- In Electronics_101@yahoogroups.com, One Two <smjones1969@s...>
                                        wrote:
                                        >
                                        > Just in case you didn't know, light and the electrical signal
                                        propagate at roughly the same speed. I seriously doubt you would
                                        need to be concerned in the small difference in speed between the
                                        two for your application. If you instead use an electrical signal,
                                        you will gain the advantages of it staying in the medium and an
                                        extreme variety of devices to choose from to work with your signal.
                                        >
                                        > computer50000 <computer50000@y...> wrote:I also don't know if the
                                        light is the best solution to choose. Right
                                        > now I'm looking for some solutions to my problem. What I know is
                                        that
                                        > I send a signal (probably a light ray) into some device... the
                                        light
                                        > will be divided into some nodes of the device and because of that
                                        I
                                        > will have multiple rays at the destination. But I know the moment
                                        > when a particular ray will arrive there. I need only to know
                                        whether
                                        > that particular ray has arrived there (or it was stuck somewhere).
                                        >
                                        > Do you think that I could use another kind of signal (instead of
                                        > light). At a theoretical level I work with signals, but if I want
                                        to
                                        > make an implementation probably (???) the light is the best.
                                        Because
                                        > I need SPEED.
                                        >
                                        > Any suggestions are welcomed !
                                        >
                                        > Thanks,
                                        > M
                                        >
                                        > --- In Electronics_101@yahoogroups.com, One Two <smjones1969@s...>
                                        > wrote:
                                        > >
                                        > > I don't know much about optical equipment, but I have made
                                        circuits
                                        > that detect light intensity. A photodiode, wired in a
                                        transresistive
                                        > mode, can be made to have incredibly high gains, allowing even the
                                        > smallest of light changes to be detected. The speed at which the
                                        > circuit functions will be dependent on the type of op amp you use.
                                        > >
                                        > > computer50000 <computer50000@y...> wrote:Hi there,
                                        > >
                                        > > I need a device which can measure the fluctuations, in a light
                                        ray,
                                        > > with the speed of light.
                                        > >
                                        > > I mean, I need to know if at second 10^-8 (ten to power minus 8)
                                        I
                                        > have
                                        > > a fluctuation in a light ray. I'm not interested to compute the
                                        > power
                                        > > of that ray. I'm just interested to know if at a given moment in
                                        > time
                                        > > (very, very small) it was or not a fluctuation in the intensity
                                        of
                                        > that
                                        > > ray.
                                        > >
                                        > > Is this possible?
                                        > >
                                        > > Thanks,
                                        > > Michael
                                        > >
                                        > >
                                        > >
                                        > >
                                        > >
                                        > >
                                        > > ---------------------------------
                                        > > YAHOO! GROUPS LINKS
                                        > >
                                        > >
                                        > > Visit your group "Electronics_101" on the web.
                                        > >
                                        > > To unsubscribe from this group, send an email to:
                                        > > Electronics_101-unsubscribe@yahoogroups.com
                                        > >
                                        > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                                        > Service.
                                        > >
                                        > >
                                        > > ---------------------------------
                                        > >
                                        >
                                        >
                                        >
                                        >
                                        >
                                        >
                                        >
                                        > ---------------------------------
                                        > YAHOO! GROUPS LINKS
                                        >
                                        >
                                        > Visit your group "Electronics_101" on the web.
                                        >
                                        > To unsubscribe from this group, send an email to:
                                        > Electronics_101-unsubscribe@yahoogroups.com
                                        >
                                        > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                                        Service.
                                        >
                                        >
                                        > ---------------------------------
                                        >
                                      • computer50000
                                        I cannot open the first link. Could you ckeck it again? Thanks, M ... of ... not ... ... the ... use. ... 8) ... in
                                        Message 19 of 19 , Nov 2, 2005
                                          I cannot open the first link. Could you ckeck it again?
                                          Thanks,
                                          M

                                          --- In Electronics_101@yahoogroups.com, "rtstofer" <rstofer@p...>
                                          wrote:
                                          >
                                          >
                                          > It is worth checking VOP (velocity of propogation) in any cable or
                                          > wire you select. It is not unusual for VOP to be around .8 or 80%
                                          > of the speed of light, maybe even down to 0.7. See
                                          > http://www.picwire.com/technical/paper2.html
                                          >
                                          > The VOP in a twisted pair cable might be around 0.65. See
                                          > http://www.tscm.com/riprcop.html
                                          >
                                          > At VOP of 0.65, I don't consider that anywhere close to the speed
                                          of
                                          > light.
                                          >
                                          > Knowing VOP is important in electrical design because signals do
                                          not
                                          > arrive in zero time. It is not unusual to skew a clock signal by
                                          > adding a length of wire to slow it down and realign it with the
                                          > data. Consider the multicabinet mainframe computer. Here
                                          > realignment is critical.
                                          >
                                          >
                                          >
                                          > --- In Electronics_101@yahoogroups.com, One Two <smjones1969@s...>
                                          > wrote:
                                          > >
                                          > > Just in case you didn't know, light and the electrical signal
                                          > propagate at roughly the same speed. I seriously doubt you would
                                          > need to be concerned in the small difference in speed between the
                                          > two for your application. If you instead use an electrical signal,
                                          > you will gain the advantages of it staying in the medium and an
                                          > extreme variety of devices to choose from to work with your signal.
                                          > >
                                          > > computer50000 <computer50000@y...> wrote:I also don't know if the
                                          > light is the best solution to choose. Right
                                          > > now I'm looking for some solutions to my problem. What I know is
                                          > that
                                          > > I send a signal (probably a light ray) into some device... the
                                          > light
                                          > > will be divided into some nodes of the device and because of that
                                          > I
                                          > > will have multiple rays at the destination. But I know the moment
                                          > > when a particular ray will arrive there. I need only to know
                                          > whether
                                          > > that particular ray has arrived there (or it was stuck somewhere).
                                          > >
                                          > > Do you think that I could use another kind of signal (instead of
                                          > > light). At a theoretical level I work with signals, but if I want
                                          > to
                                          > > make an implementation probably (???) the light is the best.
                                          > Because
                                          > > I need SPEED.
                                          > >
                                          > > Any suggestions are welcomed !
                                          > >
                                          > > Thanks,
                                          > > M
                                          > >
                                          > > --- In Electronics_101@yahoogroups.com, One Two
                                          <smjones1969@s...>
                                          > > wrote:
                                          > > >
                                          > > > I don't know much about optical equipment, but I have made
                                          > circuits
                                          > > that detect light intensity. A photodiode, wired in a
                                          > transresistive
                                          > > mode, can be made to have incredibly high gains, allowing even
                                          the
                                          > > smallest of light changes to be detected. The speed at which the
                                          > > circuit functions will be dependent on the type of op amp you
                                          use.
                                          > > >
                                          > > > computer50000 <computer50000@y...> wrote:Hi there,
                                          > > >
                                          > > > I need a device which can measure the fluctuations, in a light
                                          > ray,
                                          > > > with the speed of light.
                                          > > >
                                          > > > I mean, I need to know if at second 10^-8 (ten to power minus
                                          8)
                                          > I
                                          > > have
                                          > > > a fluctuation in a light ray. I'm not interested to compute the
                                          > > power
                                          > > > of that ray. I'm just interested to know if at a given moment
                                          in
                                          > > time
                                          > > > (very, very small) it was or not a fluctuation in the intensity
                                          > of
                                          > > that
                                          > > > ray.
                                          > > >
                                          > > > Is this possible?
                                          > > >
                                          > > > Thanks,
                                          > > > Michael
                                          > > >
                                          > > >
                                          > > >
                                          > > >
                                          > > >
                                          > > >
                                          > > > ---------------------------------
                                          > > > YAHOO! GROUPS LINKS
                                          > > >
                                          > > >
                                          > > > Visit your group "Electronics_101" on the web.
                                          > > >
                                          > > > To unsubscribe from this group, send an email to:
                                          > > > Electronics_101-unsubscribe@yahoogroups.com
                                          > > >
                                          > > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                                          > > Service.
                                          > > >
                                          > > >
                                          > > > ---------------------------------
                                          > > >
                                          > >
                                          > >
                                          > >
                                          > >
                                          > >
                                          > >
                                          > >
                                          > > ---------------------------------
                                          > > YAHOO! GROUPS LINKS
                                          > >
                                          > >
                                          > > Visit your group "Electronics_101" on the web.
                                          > >
                                          > > To unsubscribe from this group, send an email to:
                                          > > Electronics_101-unsubscribe@yahoogroups.com
                                          > >
                                          > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
                                          > Service.
                                          > >
                                          > >
                                          > > ---------------------------------
                                          > >
                                          >
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