[Laser] PIN Diode Suggestion

[n9jim]

Joel,
Most PIN Photo diodes have about the same effeciency. 0.45 A/W or so...

The size of the active area does affect the frequency response.
It also affects the spacial selectivity.

If you have a good lens, as in most telescopes, you can go very small 
with the detector, but your aiming will become more difficult.  In 
general though, RX aiming is much easier than TX aiming.  You can 
calculate your FOV (Field of View) for your detector size and choose the 
size you want.  But since we usually do not have a lot of extra light 
sources (at night), size is usually not critical for this.

Most of us have just "found" some detectors in the local surplus stores, 
in disk drives, or other optical devices. (sorry no recommendation)

However, if you want a middle range solution... Look at the Burr Brown 
OPT2xx series.  They have a PIN with integrated amplifier.  Specs are on 
my webpage.
www.qsl.net/wb9ajz/laser/laser.html

Jim
N9JIM (ex-wb9ajz)


JGray51182@aol.com wrote:

> Greetings,
> I have had some success with my recent attempts at light communication! 
>  Thanks to everyone for the information in the archives.   It's been very 
> helpful.  For a transmitter, I am using a visible red laser pointer switched 
> at 800Hz.  I don't know the exact wavelength.  My receiver is a 60mm 
> refractor telescope (800mm focal length) with a Radio Shack phototransistor 
> as the detector.  I am now looking to improve the detector by changing to a 
> PIN diode.  Can anyone give me some specific suggestions for a good PIN diode 
> including the part number, manufacturer, and phone number?  I don't know what 
> active area I should be looking for.  My reading tells me that the larger the 
> better, but if you get to large it would limit the frequency response.  Since 
> I am using 800 Hz, I am assuming that I should go as big as I can afford, as 
> long as I can still properly focus the light onto it.  Is this correct? 
>  Thanks for your help.
> 
> Joel N5FIW
> 
> 
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