670-690nm 500mW To3 TEC cooled Diode

Hey ,

Just got a new 670nm to 690nm TO3 package laser diode with internal photo diode , thermistor and TEC . Best 99USD diode so far .

I made and drilled the heatsink myself using the data sheet with the pin holes 40* angles from each other .

Driver is a P3 flex mod set to 1.1 Amps with the diodes rated current at 1.05 Amps . The thermistor and TEC are connected to a Die4Chill running from a 9V source with current set to 1.4 Amps . The tec controller is a "bang bang" type with it turning the TEC on at off when the temp exceeds a set point ( I have the tec driver set to 20C ) .

When running the diode at threshold ( around 500mA on this diode ) the tec driver "cool light flashes once a second or so , then at full power it just flashes faster .

So far i have no real good lenses to use with the diode apart from one from a 671nm DPSS i had a while back . to get full use of the output as its a non corrected diode I need a very short focal lens


IMG_0126 by TwirlyWhirly555, on Flickr


IMG_0127 by TwirlyWhirly555, on Flickr


IMG_0129 by TwirlyWhirly555, on Flickr


IMG_0131 by TwirlyWhirly555, on Flickr


IMG_0133 by TwirlyWhirly555, on Flickr

hey, great diode and beamshot...

I have a question, if you set the TEC to around ~5ºC anything bad would happen? Condensation? I think it should drift the WL to a more visible one and make the diode more efficient, right?

Leodahsan said:

hey, great diode and beamshot...

I have a question, if you set the TEC to around ~5ºC anything bad would happen? Condensation? I think it should drift the WL to a more visible one and make the diode more efficient, right?

Click to expand...

Thanks ,

Well for this diode , as its a To3 there is a AR coated window infront of the C-mount that the diode die sits on so the diode is sealed from the outside world , If they use something like dry nitrogen when the To3 package is sealed then there would be no issue of condensation but as the window is physical very close to the c-mount if the diode was cooled a lot then there may be condensation on the window , but the actual laser die would be fine .

This diode has a Coefficient of around 0.25-0.30nm/C , so for every 10C drop the wavelength would shift around 2.5-3nm according to the data sheet .

Any output readings? Wondering what this diode is pushing at that current.

Very nice project.

I'm asking because I will build a laser CNC router... And I want to squeeze every mW from a 9mm 445. I want to run things cool for better efficiency so I'll use a TEC with a control system to achieve a very low temperatue (the lowest possible ).
Thanks for the info... :thanks:

+1 to you

Tmack said:

Any output readings? Wondering what this diode is pushing at that current.

Very nice project.

Click to expand...

Thanks , I currently don't have a LPM so I have no idea on output , someone on here I believe has the same diode and it does around 600mW + at 1 Amp drive current ( I think )

Leodahsan said:

I'm asking because I will build a laser CNC router... And I want to squeeze every mW from a 9mm 445. I want to run things cool for better efficiency so I'll use a TEC with a control system to achieve a very low temperatue (the lowest possible ).
Thanks for the info... :thanks:

+1 to you

Click to expand...

Thanks , for something like that you could mount the diode in a hosing on a TEC then cover the thing in a plastic box and silicone seal around it with a window on it for the beam to pass though and keep moisture out , then in theory with dryish air inside the container the diode would be dropped well below 0C , You can push the diode a lot farther but eventually it will hit the optical max before the coatings on the die go bye bye xD

Well, I don't think I'll have budget to hit the optical max, so I think I'll stick with a low temperature and not test the facets coating...

What temperature you could recommend me, for an exposed system? I was thinking about 5ºc just to be safe... Measured with a precision thermometer.

Remember, depending on the humidity - condensation will appear on surfaces well above 0ºC. Just pull a cold drink from the fridge, and the moisture will collect on the surface in a matter of minutes..

Leo - this might have to be one of those things found by good 'ol experimentation. Get a cheap humidity sensor on an arduino, and watch your environment's humidity levels as you experiment. Use other open can laser diodes, like LPC-815s and keep watch on the clarity of the output profile. Water may not destroy the diode (electrically) while condensation collects, but if water dries on the facet, it may leave "water spots" - which will directly affect the output - and possibly cause COD.

Find that sweet spot where no condensation appears - and record it. If you have a really dry day, try pushing it lower again to see what happens.

Meatball said:

if water dries on the facet, it may leave "water spots"

Click to expand...

Water spots are leftover minerals from when the water evaporates. Water in the air is distilled by definition, so condensation will not leave water spots unless the window is already contaminated. This is why using breath works better than tap water for cleaning eyeglasses.

Yeah I guess I'll have to experiment myself... Time to buy some sensors on ebay...
Thanks for the suggestion meatball and cyp, will remember that. And sorry ionlaser555 for the thread derail... :beer:

How visible is the beam? Can you notice the color difference to 650nm?

Leodahsan said:

Yeah I guess I'll have to experiment myself... Time to buy some sensors on ebay...
Thanks for the suggestion meatball and cyp, will remember that. And sorry ionlaser555 for the thread derail... :beer:

Click to expand...

No worries

Atomicrox said:

How visible is the beam? Can you notice the color difference to 650nm?

Click to expand...

Its fairly visible in a dull lit room , its quite a deep red colour , I have no 650nm to compare it too unfortunately

That's cool, if you find a 650nm to compare don't forget to update us

Atomicrox said:

That's cool, if you find a 650nm to compare don't forget to update us

Click to expand...

Will Do


I pan to get a anamorphic prism pair to correct the output from the diode into a nice beam then mount it all in a housing .

Sound good, how bad is the beam compared to the 638nm diodes?

Atomicrox said:

Sound good, how bad is the beam compared to the 638nm diodes?

Click to expand...

well I don't really have any good lens to try with it , currently the best I can is what's in the photos and I lose abit of the diodes output due to the lens being far away and the beam looks like a rectangle with wings , pretty bad , after I correct the fast axis then it should look a lot better .

The second way I can correct it is use a cylindrical lens to correct the 35* fast axis then use something more common such as the axizi lenses to create the better beam