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Re: [Electronics_101] speed of light timer

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  • 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 1 of 19 , Nov 1, 2005
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      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 2 of 19 , Nov 1, 2005
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        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 3 of 19 , Nov 1, 2005
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          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 4 of 19 , Nov 1, 2005
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            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 5 of 19 , Nov 1, 2005
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              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 6 of 19 , Nov 1, 2005
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                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 7 of 19 , Nov 1, 2005
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                  --- 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 8 of 19 , Nov 1, 2005
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                    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 9 of 19 , Nov 1, 2005
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                      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 10 of 19 , Nov 1, 2005
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                        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 11 of 19 , Nov 1, 2005
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                          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 12 of 19 , Nov 1, 2005
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                            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 13 of 19 , Nov 1, 2005
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                              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 14 of 19 , Nov 1, 2005
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                                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 15 of 19 , Nov 1, 2005
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                                  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 16 of 19 , Nov 1, 2005
                                  • 0 Attachment
                                    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 17 of 19 , Nov 2, 2005
                                    • 0 Attachment
                                      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 18 of 19 , Nov 2, 2005
                                      • 0 Attachment
                                        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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