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'[EE] driving a laser diode'
2009\03\17@233410 by alan smith

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Is a laser diode any different than a normal LED, other than the wavelength its emitting?  Or does it need to be modulated?
I have some OPV332, 2.2Vf and 7mA If, so running it from 3.3V it
would require a 160ohm current limit.  But it doesnt appear to
be emitting the anticipated red dot...

So, anyone played with these?


     

2009\03\17@235424 by Bob Blick

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alan smith wrote:
> Is a laser diode any different than a normal LED, other than the wavelength its emitting?  Or does it need to be modulated?
> I have some OPV332, 2.2Vf and 7mA If, so running it from 3.3V it
> would require a 160ohm current limit.  But it doesnt appear to
> be emitting the anticipated red dot...
>
> So, anyone played with these?

Not those in particular.

Laser diodes have a threshold current. Below that they are very dim.

They also are very temperature sensitive, and above a certain
temperature the threshold current can be above the maximum current.

The one you have has a molded optic for a 4 degree beam and is infrared,
so you won't be able to see it, EVEN WITH YOUR REMAINING EYE. DON'T LOOK
AT IT. An unregulated infrared laser can be unsafe. Unlikely with such
a small one, but even so, please play safe.

Cheers,

Bob

2009\03\18@000243 by Vitaliy

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alan smith wrote:
> Is a laser diode any different than a normal LED, other than the
> wavelength its emitting?  Or does it need to be modulated?
> I have some OPV332, 2.2Vf and 7mA If, so running it from 3.3V it
> would require a 160ohm current limit.  But it doesnt appear to
> be emitting the anticipated red dot...
>
> So, anyone played with these?

Alan, isn't that an IR diode?

Vitaliy

2009\03\18@010718 by alan smith

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ah maybe it is....I need a laser pointer type emitter.  Back to the selection sheet...


--- On Tue, 3/17/09, Vitaliy <spam_OUTspamTakeThisOuTspammaksimov.org> wrote:

{Quote hidden}

> --

2009\03\18@013431 by Bob Blick

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alan smith wrote:
> ah maybe it is....I need a laser pointer type emitter.  Back to the selection sheet...

Laser diodes have a non-round, fairly wide-angle output. Typically you
would collimate and clip to make a "dot" output.

And if you need continuous use or wide temperature range, you should
have a feedback driver(OPC) and use a laser diode with monitor
photodiode built in.

Cheers,

Bob

2009\03\18@025526 by Ruben Jönsson

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>
> The one you have has a molded optic for a 4 degree beam and is infrared,
> so you won't be able to see it, EVEN WITH YOUR REMAINING EYE. DON'T LOOK
>  AT IT. An unregulated infrared laser can be unsafe. Unlikely with such
> a small one, but even so, please play safe.
>
> Cheers,
>
> Bob

You can use a digital camera/cam corder to see the IR light. The camera in a
cell phone works fine. This is very usefull when you need to do a quick test on
an IR remote control link.

/Ruben
==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
.....rubenKILLspamspam.....pp.sbbs.se
==============================

2009\03\18@034607 by Jinx

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> I have some OPV332, 2.2Vf and 7mA If, so running it from 3.3V
> it would require a 160ohm current limit.  But it doesnt appear to
> be emitting the anticipated red dot...
>
> So, anyone played with these?

A couple of times. Shelved projects, sigh. You should run them with
constant current drivers. I have the circuit for one somewhere. IIRC
it had a BC548 and BD139. One project did have modulation. I used
an IR diode with a 38kHz carrier and data so that an IS1U60 receiver
could be used at the other end. Modulation was just a gated 4093
oscillator driving a transistor in the current source

A laser tag system I used to repair had a similar drive and, just as
importantly, the brass-bodied diodes had heat sinks. They were Sharps,
really expensive (probably the "bona fide" spares price), 8mW I think

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