Why did my 642nm diode die?

[catalanjo]

Sorry I did not list it as I don't have a ruler or anything in the picture to give it some scale. It is right about 5 feet.

Ta! 15chars etc.
Cheers

[steve-o]

@stev-o
What voltage zener are you using ?

2.7V zener for mitsu ml520g51 's . Driving 'em at 333mA , Iop=253mA. Overdriving jest slightly

[catalanjo]

2.7V zener for mitsu ml520g51 's . Driving 'em at 333mA , Iop=253mA. Overdriving jest slightly

Thanks Steve!
Have you tried the ML520G55 ?

Cheers

[kitatit]

A 1 watt zener diode seems to protect the LD well, I've found. Across the leads and barely conducting, it will gulp up a voltage spike no problem.

Thanks Steve My understanding of these sort of things is pretty limited.
I was having a search around and found this;
http://www.wollemi.com.tw/product/do...at/LED_001.pdf
Do you hook up the zener like Fig3. on page 4?

@stev-o
What voltage zener are you using ?

@kitatit,
Many thanks from the "Coherent Gestapo" ...... very useful info.

Cheers

Hi catalanjo. I'm glad it helped Im fine with mechanical stuff but when it comes to electronics issues that are more complex than the basics, I get a bit overwhelmed.
We are lucky we have our PL friends to help us.

Have fun
Kit

[steve-o]

A zener diode is reverse-biased across the laser diode leads in order to clamp the voltage. It is desired to be slightly conducting prior to a voltage spike in order to improve the transient response time. I have to be out of town for a week now and then I will be back and be happy to answer the questions at that time.. Cheerz..
-steve-o

[kitatit]

A zener diode is reverse-biased across the laser diode leads in order to clamp the voltage. It is desired to be slightly conducting prior to a voltage spike in order to improve the transient response time. I have to be out of town for a week now and then I will be back and be happy to answer the questions at that time.. Cheerz..
-steve-o

Thanks for the clues Steve

Kit

[steve-o]

I'm sorry I forgot to come back and post answers on this thread.

Thanks Steve My understanding of these sort of things is pretty limited.
I was having a search around and found this;
http://www.wollemi.com.tw/product/do...at/LED_001.pdf
Do you hook up the zener like Fig3. on page 4?

Yes, exactly like on page 4, figure 3:

Have you tried the ML520G55 ?

No I haven't. The divergence specs look really good on those. Too bad I already ordered two HL6388MGs.. (I was advised against it, but I have some lenses that will work with 10 x 40 multimode LDs . 638nM@ 250mW ea.

Cheers!

[catalanjo]

I'm sorry I forgot to come back and post answers on this thread.
...... but I have some lenses that will work with 10 x 40 multimode LDs . 638nM@ 250mW ea.
Cheers!

When you say "will work with 10 x 40 multimode LDs" could you elaborate a bit on this.
What kind of beam do you get

Cheers

[steve-o]

Sorry, NDA, y'know .. (j/k ;]
I belive it's Melles Griot p/n 06 GLC 002/D . I bought them from a guy who was selling modules p/n 9154-01001/B a few years ago. I dont know the exact specs but it's about 5X5 at the ap (at 636nm) and long throw at 100 feet compares with a laserwave 473 blue divergence. Probably still wouldnt fit on small scanner mirros tho ..

[catalanjo]

That ain't so bad .... have you tried telescopes at all.... not good 4 divergence but might help fit on scanners.


Cheers