LAb C-Mount Housing

[532 with Envy]

Thanks...I'm attaching a couple of TEC's now....i'll see what kind of effect it has on the LPM reading. During the first reading I did notice that the housing started to get warm. It was only a <5 min test and it didn't stabilize in that time, the next will be TEC cooled and around 10min. I'll post the LPM result.

Edit:Sorry about the linear....This BUCK drive does look to be very well designed and put together(i'm really not the one to review this though)

 

[lazeerer]

Thanks...I'm attaching a couple of TEC's now....i'll see what kind of effect it has on the LPM reading. During the first reading I did notice that the housing started to get warm. It was only a <5 min test and it didn't stabilize in that time, the next will be TEC cooled and around 10min. I'll post the LPM result.

Edit:Sorry about the linear....This BUCK drive does look to be very well designed and put together(i'm really not the one to review this though)

Sweet cant wit to see your numbers with the Tec's. I never thought about using tec's.

That gives me an Idea and get a thick piece of aluminum for the base maybe 3/8" thick and then place the tec's down with the housing on top.

IT does though look like a Slow nd steady drop. With the tec's i bet it will stabilize in Half the time and not drop in power as much.

 

[Devil_Master]

Sorry if this is considered necroposting, but I was looking for threads about C-mount housings and I found this one, which surprised me in a good way. Until now, I thought that a "weird" shape like a C-mount would need a strange and expensive housing... instead it uses the same kind of heat sinked housing that I've seen at O-Like for years! And the pictures in this thread even show how the diode itself is mounted! Much simpler than I thought.
Then I read a description that left me wondering...

The Lens Has A very Long FL. Iam Guess 40mm. So from where the diode is to where the lens is you will loose alot of Light. It seems like there might of been another lens that was suppose to go in between the diode and the Focusing Lens. The Reason i think this is there is another set screw toward the Middle of the Housing that might have been there to hold another lens in the housing. Maybe an Expanding lens to have the light more concentrated rather then having it Expand just from the diode.

If this is true, has anyone ever opened an IR labby from O-Like to check whether some of the light from the diode is dispersed too much and heats the heat sink instead of reaching the lens? Could it be that you just need to add a lens before the focussing lens in order to increase the power of those lasers and keep the heat sink cooler?

 

[Bob_Boyce]

Sorry if this is considered necroposting, but I was looking for threads about C-mount housings and I found this one, which surprised me in a good way. Until now, I thought that a "weird" shape like a C-mount would need a strange and expensive housing... instead it uses the same kind of heat sinked housing that I've seen at O-Like for years! And the pictures in this thread even show how the diode itself is mounted! Much simpler than I thought.
Then I read a description that left me wondering...

If this is true, has anyone ever opened an IR labby from O-Like to check whether some of the light from the diode is dispersed too much and heats the heat sink instead of reaching the lens? Could it be that you just need to add a lens before the focussing lens in order to increase the power of those lasers and keep the heat sink cooler?

I'm sure there are some that will consider it necroposting, but when an old thread holds pearls of wisdom that are still relevant then it may be best to bring it back to the surface from time to time. This would be one of those, since C-mount solutions are few and far between.

I read through this thread, and the questions you have should have been addressed before. Had I been active in this forum when this thread was active, I would have offered some suggestions that could have helped. Unfortunately, hobby lasers tend to ignore one of the fundamental issues that plague multimode laser diode use. Unfocused emissions tend to look like a bar, instead of a dot or close to round oval. It's hard to get a good dot shape in the majority of these builds. The emissions that do not make it through the optics cause a loss in optical output power, and can contribute to heating up the host in the higher powered builds.

I work with bar mount, C-mount, and 9mm laser diodes more than I do with the smaller ones. This is because I use higher power lasers for research. I prefer to build my own labbies rather than buy because I can build them to exactly what I need, and save money in the process. Because of this, I have some familiarity working with these larger multimode laser diodes.

The answer you seek lies in the use of Fast Axis Correction (FAC) optics. The emissions from the laser diode diverge faster on one axis as compared to the other. Adding a FAC optic very close to the front facet of the laser diode can correct this to allow more of the laser emission to enter the collimation/focus optic(s). You can find FAC optics on eBay or other sources, but try to stay away from plastic optics for the higher power laser diodes.

Obviously, the pros use FAC optics that are coated for the wavelength in use, but even uncoated FAC optics are better than no FAC optic at all. Do a little study on the subject and you may just find that you can improve upon your results with very little effort. There's plenty of room in most C-mount hosts for adding a small FAC optic right to the front of your C-Mount laser diode. Another option might be to buy a C-mount laser diode that already has a FAC installed.

I hope this helps

Bob

 

[Devil_Master]

So I searched "FAC lens" on Ebay and found this:
5W 808nm Laser Diode C Mount with Fac Lens | eBay
I suppose the gray half-cylinder in the corner is the FAC lens, because I searched "c-mount laser diode" on Google, and the diodes in the pictures I found don't have that part.

I wonder what driver would be necessary to power that diode. I found this this one in this thread about another 5W 808nm diode, is it appropriate? (It seems rather small, compared to the drivers powering the O-Like labbies of comparable power based on C-mounted diodes...)

 

[Bob_Boyce]

So I searched "FAC lens" on Ebay and found this:
5W 808nm Laser Diode C Mount with Fac Lens | eBay
I suppose the gray half-cylinder in the corner is the FAC lens, because I searched "c-mount laser diode" on Google, and the diodes in the pictures I found don't have that part.

I wonder what driver would be necessary to power that diode. I found this this one in this thread about another 5W 808nm diode, is it appropriate? (It seems rather small, compared to the drivers powering the O-Like labbies of comparable power based on C-mounted diodes...)

I'm not seeing a FAC optic on the C-mount in that photo. In the sketch at the bottom right of that listing, that arch from the cathode lead to the laser die is an illustration of a row of bond wires that make the cathode electrical connection to the die. If a FAC optic is included seperately, it's not shown in the listing. If it were a micro or mini FAC installed on the laser diode in the photo, it would be installed directly over the facet of the die and attached to the C-mount by one or two tiny dabs of adhesive. It would be clearly visible at that level of magnification.

For an example of the visibility of a mounted FAC, check out this 500mW 808nm C-mount

http://www.ebay.com/itm/251173252699

Bob

 

[Bob_Boyce]

The purpose of the FAC is to shape the emissions of multimodes to attempt to bring the fast axis divergence back on par with the slow axis divergence. For example, on a multi-mode laser diode with slow axis divergence of 10 degrees and fast axis divergence of 70 degrees, you would want to correct that fast axis divergence to as close as you can get to that slow axis divergence of 10 degrees. Typically we add a collimation optic after the FAC, unless it is going to be used as a DPSS pump.

Bob

 

[Devil_Master]

For an example of the visibility of a mounted FAC, check out this 500mW 808nm C-mount

808nm 3nm 500mW C Mount Infrared IR Laser Diode with Fac for Green Laser Pump | eBay

Oh, now I see it! I was looking in the wrong place. You're right, the picture of the original object I posted doesn't show anything of the sort. I'll ask the seller for explanations.

The purpose of the FAC is to shape the emissions of multimodes to attempt to bring the fast axis divergence back on par with the slow axis divergence.
(cut)
Typically we add a collimation optic after the FAC, unless it is going to be used as a DPSS pump.

Yes, I know that part of the theory. What I lacked was information about the look and position of that lens in practice.

EDIT:
The seller replied and added two pictures where the FAC lens can be seen.