685nm and 690nm laser diodes

[RA_pierce]

I have been looking for some interesting red wavelengths to add to my collection.
685nm diodes can be found on eBay at ~15mW but I would like more power than that.
During my search, I stumbled upon these:
685nm 50mW
690nm 35mW

Just thought I'd share in case anyone else is interested.
I may try the 50mW 685.

Here is a link to a datasheet for a 55mW 685 from Ushio:
https://www.ushio-optosemi.com/documents/uos/products/UOSE_DS_HL6750MG_Rev0.pdf
And another from opnext with the same product code:
https://www.digchip.com/datasheets/parts/datasheet/625/HL6750MG-pdf.php

 

[CurtisOliver]

Yep, came across HL6750MG's myself when adding to the wavelength thread.
Thorlab's offers them for ~$80 each for 1-5 units. Don't know if there are any cheaper sources.

 

[BowtieGuy]

Thanks for the links, RA; I've also been looking for new wavelengths, and that 685nm sounds interesting.
I have a 674nm that I picked up from ultimatekaiser a while back, and it's a very nice wavelength.

 

[Shotgundrums]

Great find man!! I’ve been sorta interested in these darker reds too. Would make for a pretty interesting pointer. Thanks for the link too!
SGD:beer:

 

[steve001]

When pointers first became available they were all 670nm. A nice red red but dim. Why would one want a dim laser?

 

[Lifetime17]

Hi Steven ,
Some folks collecting differences WL enjoy it . Diode set to higher amp have a shift in colors

Rich

 

[steve001]

Hi Steven ,
Some folks collecting differences WL enjoy it . Diode set to higher amp have a shift in colors

Rich

Understandable and more so for colors not easily gotten. So it shifts a few nanometers red is still red and still dim. If I were to spend money on a wavelength it would be a uncommon wavelength. Just my opinion

 

[Cyparagon]

Once you get above standard DVD diodes at 662nm, all the reds and infrareds look about the same. They get dimmer, which many confuse with "deeper".

 

[RA_pierce]

Once you get above standard DVD diodes at 662nm, all the reds and infrareds look about the same. They get dimmer, which many confuse with "deeper".

It should be so.
There is very little or no overlap in the response spectra for our cones beyond 650ish nm, so wavelengths longer than that will be detected by only one type of cone cell.
Compare that to wavelengths around 470-510 nm, where all three cone photoreceptors overlap - color perception is particularly acute in this range, as has been noted by several cyan enthusiasts here.

Understandable and more so for colors not easily gotten. So it shifts a few nanometers red is still red and still dim. If I were to spend money on a wavelength it would be a uncommon wavelength. Just my opinion

The same is true of the violet side of the spectrum. I just want to fill out the reds in my collection. I haven't seen anything longer than 638nm in a while so I'm trying to get something at the edge of discernible red (660) and something just beyond that threshold that isn't as dim as 780.

 

[steve001]

It should be so.
There is very little or no overlap in the response spectra for our cones beyond 650ish nm, so wavelengths longer than that will be detected by only one type of cone cell.
Compare that to wavelengths around 470-510 nm, where all three cone photoreceptors overlap - color perception is particularly acute in this range, as has been noted by several cyan enthusiasts here.



The same is true of the violet side of the spectrum. I just want to fill out the reds in my collection. I haven't seen anything longer than 638nm in a while so I'm trying to get something at the edge of discernible red (660) and something just beyond that threshold that isn't as dim as 780.

Since it makes you happy go ahead.

 

[Atomicrox]

I have a 30mW 685nm and it's pretty nice. Very dim and slightly different from 650nm, but I can only see the difference side by side. The 685nm looks more "crimson" while the 650nm looks "pure red".
I doubt going up to 50mW will make much difference, you'd probably need a few hundred mW to get a visible beam without fog.

 

[Benm]

I suppose collecting wavelengths would be the only reason.

At some point it just becomes very dim and you may change your description of the color. Things like orange and brown are essentially the same wavelength mix, with the difference just being the brightness.

Then again we don't usually do this: we don't call very weak white flashlights gray.

You have similar color naming problems like purple (pure wavelength, say 410 nm) versus magenta (mix of red and blue). But then again we usually don't call bright purple magenta, though 'pink' can refer to both unsaturated magenta and a mix of white and violet... tricky!

 

[10fenny]

I had a 685 build awhile back. It wasn't anything too special.. but pics came out really cool with it

 

[ultimatekaiser]

Yeah I have one of the 690s from thorlabs, back when they were like $56 or something. Very good quality when paired with my good lab driver. I always liked the 690nm region of light. is a very dark and deep blood/ruby red color. 35mW is pretty good tbh, for that low into the red region, especially for a single mode diode. I can get mine very stable with some effort. I could probably make holograms with it on a stable enough surface and some work.