505nm and 480nm diode RESULTS

[Alaskan]

Tks Paul, found it: Survival Laser Driver

 

[styropyro]

It will depend on how well it is heat sinked. In a pen build, yes it will heat up and increase in wavelength. At lower currents and heat sinked well, not so much.

Just gonna add for all to see that these InGaN diodes (violet through green) don't shift nearly as much as as the red diodes with temperature and current. I don't know the wavelength vs. current slope off the top of my head, but cooling one of these diodes from room temp to -196C (liquid nitrogen) will only give you a drop of about 4nm. This is good if you want to drive the hell out of them, but bad if you want to cryo shift them.

On a side note, I bought a 505nm diode on eBay when they first started popping up, and now I can't find my diode for the life of me.

 

[Singlemode Laser]

Just gonna add for all to see that these InGaN diodes (violet through green) don't shift nearly as much as as the red diodes with temperature and current. I don't know the wavelength vs. current slope off the top of my head, but cooling one of these diodes from room temp to -196C (liquid nitrogen) will only give you a drop of about 4nm. This is good if you want to drive the hell out of them, but bad if you want to cryo shift them.

The shift for the GaN diodes is 1nm every ~20°C compared to 1nm every ~3°C for the GaAs red ones.

So ist only 10nm with cryo cooling and hard to see without a comparison beam.

Singlemode

 

[styropyro]

At least in my experience, dλ/dT decreases in magnitude at low temps. I dunked a 635nm diode in liquid N2, and the wavelength only dropped to 610nm. That gives an average slope of ~0.11nm/K. I'd imagine the green diodes would also show similar behavior.

 

[paul1598419]

What I meant by wavelength shift with these diodes is if they are allowed to get hot enough that to touch it will burn you, the shift is 2nm to 3nm. With these low wavelength diodes, I consider this to be significant. But, they don't shift at all like the red diodes. In a pen build, with no heat sink, these can shift from 502nm up to 505nm. To me that is significant enough to be avoided.

 

[CurtisOliver]

Yep, definitely. A 3nm shift on that part of the spectrum results in a noticeable colour change.

 

[Atomicrox]

I don't think it's just the die material that determines WL-shift under high current. There are a few diodes built with the same materials that shift a lot more than the others (e.g. NDB7675).

 

[Zom-B]

Oh Paul, I see you have an Ocean Optics spectrometer. How much was it? The Ocean Optics JAZ that I use at work is definitely outside of a hobby budget (~$1500)

 

[paul1598419]

It wasn't cheap. I had been wanting one for several years. Finally pulled the trigger about 18 months ago. Now I have several of the B&W Tek BTC100 spectrometers. Am in the process of aligning two to make up the upper and lower wavelengths it doesn't cover.

BTW, I am going to Seattle in the morning for surgery and won't be back for two to three weeks.

 

[ultimatekaiser]

Well, due to the lack of case positive drivers at low current I finally got un-lazy enough to diagnose and fix my LDC240C. Assuming its calibration is intact (probably not, but likely very close) the diode I bought from Dr.Laser (an SB1573N91) is doing rated power (35mW) at 142mA when cool and runs at 503.1nm +/-0.1nm based on my HR2000 spectrometer. 200mA yields about 58mW at 504.8nm and is about 502nm at 5mW. Not too shabby. I'll be testing some SB217HL91s soon, and will report back.

 

[paul1598419]

Nice, Matt. I have been testing a lot of these "505nm" Sharp diodes and have found many to be anything but 505nm. They do drift up in wavelength with current, but not as much as some other diodes do. Any new information you can bring to this thread is greatly appreciated.

 

[ultimatekaiser]

yeah these diodes wander a bit more with current than temperature, though higher current does contribute to more heat. The linewidth also would go up quite a bit too. The line-width of diodes in general is much wider than DPSS mind you, (if that was my 488 sapphire it'd be pretty much a straight line peak) but it is definitely noticable here. It doesn't take much-10s of mA make a difference here compared to something like a 445 1W diode or something. I'll happily test anything else I can get my hands on, especially now that my 4A driver is working again.

 

[paul1598419]

All these direct diodes have a fairly wide line width. I have noticed that with all the diodes I've tested. In the 505nm range, that is over 30 diodes in total. I've also tested a few of the "480nm" diodes that pretty much weren't. I'll have a "495nm" in hand soon that I'm hoping will be at least 490nm. If so, I'll probably get one for myself. Sorry, I don't have a link for them yet so I can't pass that along. Still, pretty exciting to maybe have a 490nm+ diode. :yh:

 

[ultimatekaiser]

All these direct diodes have a fairly wide line width. I have noticed that with all the diodes I've tested. In the 505nm range, that is over 30 diodes in total. I've also tested a few of the "480nm" diodes that pretty much weren't. I'll have a "495nm" in hand soon that I'm hoping will be at least 490nm. If so, I'll probably get one for myself. Sorry, I don't have a link for them yet so I can't pass that along. Still, pretty exciting to maybe have a 490nm+ diode. :yh:

Yeah its a general issue that is inherent to diode lasers in general. Which is why they're not really used for certain sciences for accuracy sake. That 492 sounds promising. I haven't had a 492nm in my hands since i fixed a friend's Calypso DPSS.

 

[Singlemode Laser]

All these direct diodes have a fairly wide line width. I have noticed that with all the diodes I've tested. In the 505nm range, that is over 30 diodes in total. I've also tested a few of the "480nm" diodes that pretty much weren't. I'll have a "495nm" in hand soon that I'm hoping will be at least 490nm. If so, I'll probably get one for myself. Sorry, I don't have a link for them yet so I can't pass that along. Still, pretty exciting to maybe have a 490nm+ diode. :yh:

Can't wait for some measurements of this new "495nm" diodes. Hope they are real and shine like diamond

Singlemode

 

[Apocalypse]

When does it start to become green instead of blue? are 495nm diodes more greenish or blueish?