Heruursciences diode grab bag thread

[MarioMaster]

This should help you guys out for testing diodes:

IR: Threshold Current Nominal Current Voltage

100mW 0.05 0.15A 2.5v

1 watt 0.2A 1.2A 2.2v

2 watt 0.4A 2.2A 2.2v

4 watt 0.6A 4.5A 2.2v

6 watt 1.2A 8.5A 2.2v

C-block is positive
Fly lead is negative

 

[Zithras]

Much better than mine - thanks! Does the threshold current chart work for the cmounts too?

 

[MarioMaster]

Much better than mine - thanks!  Does the threshold current chart work for the cmounts too?

Yeah it should be the same, although I don't really have much information on the reds. So use the data in the table for only IR diodes

 

[icecruncher]

Ditto on the thanks.

Looking forward to checking what I have.

 

[heruursciences]

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Thank you for buying from me your goodies will arrive shortly )

 

[cappernicus]

Mariomaster, what exactly do you mean by threshold? Because all the diodes that I got in my grab bag (except for the long-wave IR) put out light starting at about 3mW and just get brighter when I increase the current.

 

[jwc]

Mariomaster, what exactly do you mean by threshold? Because all the diodes that I got in my grab bag (except for the long-wave IR) put out light starting at about 3mW and just get brighter when I increase the current.

The threshold current is the minimum current needed for actual lasing IIRC.

 

[cappernicus]

The threshold current is the minimum current needed for actual lasing IIRC.

Yes, but does that mean that it will emit incoherent light until it hits that threshold or what? Because my results showed that the threshold at which they lit up was far below that on all of them. :-/

 

[MarioMaster]

[quote author=jwc link=1238120462/64#70 date=1241041333]The threshold current is the minimum current needed for actual lasing IIRC.

Yes, but does that mean that it will emit incoherent light until it hits that threshold or what? Because my results showed that the threshold at which they lit up was far below that on all of them. :-/[/quote]

Yes they will glow below that, but they won't actually output coherent light until you hit the threshold current.

 

[cappernicus]

How do I tell if the light is coherent or not?

 

[Bob_Boyce]

How do I tell if the light is coherent or not?

If it speaks clearly, then it may be coherent
If it mumbles or babbles, then it may be incoherent
Sorry, could not resist ;-)

Without test equipment.
This may not help you with the IRs, but this may help you with visible output LDs...
Coherent light in the visible spectrum should appear to "sparkle" as your eyes detect the interference patterns present. Incoherent light would just illuminate without those visible interference patterns.

Otherwise, test equipment could be used.
One test would be to compare optical output power to electrical power input, ie efficiency, as you increase electrical power input. As you pass the threshold and lasing begins, optical power output vs electrical power input should begin to increase very measurably.

I hope this helps

Bob

 

[icecruncher]

[quote author=Cappernicus link=1238120462/64#73 date=1241053362]How do I tell if the light is coherent or not?

If it speaks clearly, then it may be coherent
If it mumbles or babbles, then it may be incoherent
Sorry, could not resist ;-)

[/quote]


I was thinking the same thing, but decided against posting it.

 

[Warske]

This should help you guys out for testing diodes:
IR: Threshold Current    Nominal Current  Voltage...

Thanks for your threshold vs nominal data for IR diodes.  It looks very useful.  I used Excel to run a trend line through it, getting y = 7.3791x - 0.3057 (see pic).

I was wondering
1) How well do you think this would scale to higher and lower power?
2) Is "nominal" power closer to the 10,000 hour life on the datasheets, or more like the "pushed" 10 hour life that many LPM members are doing?
3) Do you expect the power to be temperature rise limited or optical power limited?
4) Is this mostly for 808nm, or all other IR also?

I realize this is "fat thumb" reckoning, but would much appreciate any insights...

 

[cappernicus]

Thanks. Yeah all of mine are infrared. I wouldn't notice any sparkling through the camera. The power meter is a good idea though...

 

[MarioMaster]

I used my power meter to detect lasing - the die glow would produce little or no reading then there would be a sudden spike once the diode hit the threshold current.

 

[icecruncher]

I don't think this has been mentioned:

http://members.misty.com/don/laserdio.htm#diodct0

Good reference section for how to test unknown diodes.