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Re: [buildcheapeeg] build your own treatment instrument

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  • hrebesh ms
    Optical Topography-Principles of Near Infrared Spectroscopy (NIRS) Weak near infrared light of about 1.5mW from a laser diode is illuminated onto head from
    Message 1 of 3 , Jun 5, 2003
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      Optical Topography-Principles of Near Infrared Spectroscopy (NIRS)
       
        
      Weak near infrared light of about 1.5mW from a laser diode is illuminated onto head from optical fibers attached to the scalp. This light passes through the skull and reaches the cerebral cortex. It penetrates to a depth of about 3cm and is scattered by hemoglobin in the blood. The light is partially reflected back through the scalp. The reflected light is detected 3cm from the original illuminated point. In adults, the light attenuates to a level as low as a hundred millionth or even a billionth of the irradiated light. The reflected light is sent through optical fibers and received with a highly sensitive avalanche photodiode detector.

      The figure on the left is the molecular absorption coefficient of oxy- and deoxy-hemoglobin. Brain activity is characterized by the firing of neurons. This results in active energy metabolism and causes secondary increase in blood volume to supply glucose and oxygen to the tissues. Thus, the change in concentration of hemoglobin is an important index for the brain activity.

      The reflected light is measured every 0.1 seconds, and the latter measured data is subtracted from the former to determine the concentration change of hemoglobin. The intensity of the reflected light depends on the respective concentration of the two kinds of hemoglobin. Two kinds of laser diodes (780nm and 830nm) are used to separate the two kinds of hemoglobin concentration changes independently.



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    • Darwin
      Sounds interesting, but were you trying to send (attached) PIX/ schematic, etc...? The email msg was only 8kb and contained 2 empty PHOTO shells, but no PIX-
      Message 2 of 3 , Jun 5, 2003
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        Sounds interesting, but were you trying to send (attached) PIX/ schematic, etc...?

        The email msg was only 8kb and contained 2 empty PHOTO shells, but no PIX-
        so could you try sending them again, or elaborate further on what we are missing?

        Darwin

        PS: I thought this group had moved, I just happened to still be on [email]
        delivery.
        --------------------------------------------------------------------------------

        hrebesh ms wrote:

        >
        >
        Optical Topography-Principles of
        Near Infrared Spectroscopy (NIRS)




        Weak near infrared light of about
        1.5mW from a laser diode is
        illuminated onto head from optical
        fibers attached to the scalp. This
        light passes through the skull and
        reaches the cerebral cortex. It
        penetrates to a depth of about 3cm
        and is scattered by hemoglobin in
        the blood. The light is partially
        [Image]reflected back through the scalp.
        The reflected light is detected 3cm
        from the original illuminated point.
        In adults, the light attenuates to a
        level as low as a hundred millionth
        or even a billionth of the
        irradiated light. The reflected
        light is sent through optical fibers
        and received with a highly sensitive
        avalanche photodiode detector.
        [Image]The figure on the left is the
        molecular absorption coefficient of
        oxy- and deoxy-hemoglobin. Brain
        activity is characterized by the
        firing of neurons. This results in
        active energy metabolism and causes
        secondary increase in blood volume
        to supply glucose and oxygen to the
        tissues. Thus, the change in
        concentration of hemoglobin is an
        important index for the brain
        activity.

        The reflected light is measured
        every 0.1 seconds, and the latter
        measured data is subtracted from the
        former to determine the
        concentration change of hemoglobin.
        The intensity of the reflected light
        depends on the respective
        concentration of the two kinds of
        hemoglobin. Two kinds of laser
        diodes (780nm and 830nm) are used to
        separate the two kinds of hemoglobin
        concentration changes independently.
        >
        >
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