detectation of laser rays

Dear Sir,
I need to detect a laser ray in a project. At first I thought to use LDR for this purpose but it detects sunlight too. I have to test it in field so it will not solve the purpose. Now I am thinking to use color sensors (like TCS3200,TCS3210) for this purpose. Because sunlight is white and laser is red color. But I am in doubt that it will work or not.

So please tell me just one thing that if I take a color sensor (TCS3200,TCS3210) and put a red color Laser on it it will sense or not.

Comments

  • 12 Comments sorted by Date Added Votes
  • neeladrinath,
    This is not a trivial problem.
    Almost certainly you have to modulate the laser beam and filter the sensor input to detect its presence.
    This is very much the same approach as 40kHz modulated IR controllers as used for TV remotes etc.
  • It means before color sensor some filter component is needed to filter out other lights from laser.
  • The short answer is yes, you can detect the laser light, but it requires a bit of work. The simplest method would be to modulate the laser as macrobeak suggested.

    If modulating the laser is not practical there is an alternate way to detect the laser light.
    From the TCS3200/3210 data sheet "In the TCS3200, the light-to-frequency converter reads an 8 x 8 array of photodiodes. Sixteen photodiodes have blue filters, 16 photodiodes have green filters, 16 photodiodes have red filters, and 16 photodiodes are clear with no filters."

    What you can do is measure the intensity of the ambient light without the laser light on all four outputs and use that measurement as a form of background subtract to determine when the laser is shining on the TCS chip.

    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • kwinn wrote: »
    The short answer is yes, you can detect the laser light, but it requires a bit of work. The simplest method would be to modulate the laser as macrobeak suggested.

    If modulating the laser is not practical there is an alternate way to detect the laser light.
    From the TCS3200/3210 data sheet "In the TCS3200, the light-to-frequency converter reads an 8 x 8 array of photodiodes. Sixteen photodiodes have blue filters, 16 photodiodes have green filters, 16 photodiodes have red filters, and 16 photodiodes are clear with no filters."

    What you can do is measure the intensity of the ambient light without the laser light on all four outputs and use that measurement as a form of background subtract to determine when the laser is shining on the TCS chip.


    Wonder application for the sensor. I'm sure that could be fine tuned for different color lasers, green go/red stop. Gives me another reason to use it, other than ambient light.
  • MikeDYur wrote: »
    kwinn wrote: »
    The short answer is yes, you can detect the laser light, but it requires a bit of work. The simplest method would be to modulate the laser as macrobeak suggested.

    If modulating the laser is not practical there is an alternate way to detect the laser light.
    From the TCS3200/3210 data sheet "In the TCS3200, the light-to-frequency converter reads an 8 x 8 array of photodiodes. Sixteen photodiodes have blue filters, 16 photodiodes have green filters, 16 photodiodes have red filters, and 16 photodiodes are clear with no filters."

    What you can do is measure the intensity of the ambient light without the laser light on all four outputs and use that measurement as a form of background subtract to determine when the laser is shining on the TCS chip.


    Wonder application for the sensor. I'm sure that could be fine tuned for different color lasers, green go/red stop. Gives me another reason to use it, other than ambient light.

    Absolutely. Having the filters for different wavelengths and an unfiltered sensor makes that a great chip for a multitude of uses. By using the unfiltered sensor as a reference the other sensors can be used for ratio-metric measurements, and that opens up a whole lot of possibilities.
    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • Sorry I meant, wonderful application for the sensor.
  • MikeDYur wrote: »
    Sorry I meant, wonderful application for the sensor.

    So did I.
    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 20,933
    edited April 6 Vote Up0Vote Down
    The laser is likely to overpower the sensor without a heavy neutral density filter in front of it. But such a filter will also help in reducing the effects of ambient light.

    You should also put the detector in the end of a tube that's painted black inside to further reduce ambient lighting interference.

    Also, your aim will have to be spot on unless you can defocus the laser a bit to make the target spot bigger. Still, you will need to make the mountings for both the laser and the sensor quite rigid to keep the aim from shifting.

    I would also like to second macrobeak's idea of modulating the laser beam. This won't work with the TCS3200 chip, though. But you could probably use just a garden-variety phototransistor with a color filter in front of it, in addition to the caveats I mentioned above. Your controller program will then have to detect whether the signal it's receiving is modulated or not to determine whether the response is actually from the laser.

    'Sounds like a fun project. Care to divulge what the application is?

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • Can i do it by using led ?

    if yes what color led is required and what wavelength it can detect ?
  • Can i do it by using led ?

    if yes what color led is required and what wavelength it can detect ?

    For the led to work as a detector it should emit light at a wavelength close to what the laser puts out, so for a red laser a red led.
    In science there is no authority. There is only experiment.
    Life is unpredictable. Eat dessert first.
  • Neeladrinath,
    As I posted elsewhere, here is a really nice laser detection project;
    http://blog.svenbrauch.de/2017/02/19/homemade-10-mbits-laser-optical-ethernet-transceiver/
  • ercoerco Posts: 17,854
    See also http://forums.parallax.com/discussion/comment/1393404/#Comment_1393404 for a modulated laser sensor which has a fair amount of sunlight rejection. You could transmit a signal from one and receive on another. Using one outdoors on a sunny day at noon (sensor shaded from direct sun), I could easily sense the reflection from a piece of Scotchlite reflector at 50 feet.

    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
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