modulating light

Discussion in 'General Electronics Chat' started by aac9876, May 25, 2007.

  1. aac9876

    Thread Starter Active Member

    Dec 9, 2006
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    0
    one of the companies on my stock watch list makes products that modulate
    light waves for electronics uses. Optical nubiate. etc or something.
    Light cant be measured by frequency right.?? How could you read little
    bits of modulated light waves. ?? Would it be similar to radio freq. ??;):eek:
     
  2. Tube Tech

    Active Member

    Jan 11, 2007
    46
    0
    Probably modulating light for use on fiber optics. On-Off, not AM or FM or quadrature shift.
     
  3. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    I believe that some of the old laser based distance measuring equipment had a light modulator that could modulate the intensity of the aggregate laser beam.

    hgmjr
     
  4. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    I once maintained some fax machines which "modulated" the laser beam with a varying degree of partial blockage.
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,175
    1,798
    Since light is the same kind of electromagnetic radiation as radio waves it certainly can be "measured in frequency". It follows the the same relationship as radio waves, namely:
    Code ( (Unknown Language)):
    1.  
    2. c = f * lambda
    3.  
    4. where c is the speed of light, approximately 3e8 meters/second
    5. and f is the frequency in Hertz
    6. and lambda is the wavelength in meters
    7.  
     
  6. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    145
    Indeed so, visible light occupies the portion of the electromagnetic spectrum between ~450 and 750THz.

    Dave
     
  7. Papabravo

    Expert

    Feb 24, 2006
    10,175
    1,798
    And wavelengths of 400 nanometers to 700 nanometers
     
  8. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    The beauty of using light, is that you can use several wavelengths in one cable, and they won't interfere, since they can be separated by simple optics.
     
  9. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Thus we have "multimode" fiber!:)
     
  10. Dennis Atwood

    New Member

    May 26, 2007
    8
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    i thought multimode cable transmitted light at the same wavelength, but in several different reflection angles within the cable
     
  11. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Yes. Multiple propagation modes allow effective transmission at different simultaneous wavelengths. As an example, we can transmit at 850u while recieving at 1300u. (Assumes we are using the expensive cards.)

    In common practice, only one wavelength is used, and xmt/rcv are on different fibers. This uses affordable cards.
     
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