IR Laser diode focusing and module selection for CSEL Laser pointer

In summary, IR laser diode focusing and module selection are critical components in the design of a CSEL laser pointer. The focusing of the IR laser diode must be precise to ensure a tightly focused beam and avoid unwanted divergence. Module selection involves considering factors such as wavelength, power output, and temperature stability to ensure optimal performance of the laser pointer. Careful consideration and proper calibration of these components are necessary to achieve a high-quality, reliable CSEL laser pointer.
  • #1
Mike Gaffer
24
0
TL;DR Summary
Building an IR pointing laser - need help selecting a CSEL laser diode and suggestions on how to focus it.
I'm attempting to build an IR laser pointer.
It needs to operate at 850nm (IR spectrum).
It has to be as close to a "dot" at 250 feet as possible (columnated beam, and not a wide "flashlight" type beam).
Power output should be around 150mW.
I need to control the brightness from 5mw to 150mw electronically. (was considering a driver that could current limit the output variably, or PWM).
The laser module has to be CSEL (Cavity Surface Emitting Laser).

My questions are:

1) any suggestions in finding a CSEL module that would work for something like this, that is reasonably priced?

2) what is needed to select a lens to columnated the beam, so it doesn't diverge like a flashlight?

3) would PWM or current limiting work on a module like this to control brightness?

Any thoughts would be GREATLY appreciated!

Thanks in advance everyone!
 
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  • #2
Others will give you better thoughts than I can on this, but I had a couple questions to clarify things a bit.

Can you use optics near the far end to focus the laser beam? If the laser beam diameter were something like 10cm there, could you use a lens to generate your focused spot? Also, what is the stability of the air like between your laser diode and the place 250' away? Are you assured that they will be no thermal gradients or other sources of distortion on the beam over that distance?
 
  • #3
berkeman said:
Others will give you better thoughts than I can on this, but I had a couple questions to clarify things a bit.

Can you use optics near the far end to focus the laser beam? If the laser beam diameter were something like 10cm there, could you use a lens to generate your focused spot? Also, what is the stability of the air like between your laser diode and the place 250' away? Are you assured that they will be no thermal gradients or other sources of distortion on the beam over that distance?
10cm at 250 feet is acceptable.
Optics / lenses would have to go as close to the diode as possible.
This is for mounting on a weapon as a pointing device - so air stability is not a factor as there will be many environmental influencers.
 
  • #5
Its my first time using a VCSEL laser -- so I was uncertain if it needed focusing or was just normally columnated to some degree coming out of the module. I own a few of similar hand held lasers to this:
https://www.ebay.com/itm/325596205550
and if I unscrew the lens, the diode module in the back of the receiver/head sink throws a beam that appears to spread at around (estimated) 30 degrees.
 
  • #6
CSEL (Cavity Surface Emitting Laser) - I MEANT VCSEL
Vertical Cavity Surface Emitting Laser...
 
  • #7
My Google-foo is not having a lot of luck, but it seems that existing IR laser guided bomb optics would be a good field to look into. Have you had any luck finding references for that field?

1687384719520.png

https://en.wikipedia.org/wiki/Laser-guided_bomb
 

1. How do I focus an IR laser diode for a CSEL laser pointer?

Focusing an IR laser diode for a CSEL laser pointer involves adjusting the position of the lens to achieve the desired beam width and intensity. This can be done by rotating the lens or moving it closer or farther from the diode. It is important to use caution and protective eyewear when handling laser diodes.

2. What factors should I consider when selecting a module for a CSEL laser pointer?

When selecting a module for a CSEL laser pointer, it is important to consider the wavelength, output power, and beam divergence of the laser diode. Other factors to consider include the size and shape of the module, as well as any additional features such as adjustable focus or built-in safety mechanisms.

3. How do I determine the appropriate output power for a CSEL laser pointer?

The appropriate output power for a CSEL laser pointer depends on the intended use of the laser. For general use, a lower output power of 5-10mW is recommended to avoid potential eye damage. However, for specific applications such as astronomy or industrial use, a higher output power may be necessary.

4. What is the difference between a CSEL laser pointer and a traditional laser pointer?

A CSEL laser pointer uses a semiconductor laser diode as the light source, while a traditional laser pointer typically uses a gas or solid-state laser. CSEL laser pointers are more compact, efficient, and cost-effective compared to traditional laser pointers.

5. Are there any safety precautions to keep in mind when using a CSEL laser pointer?

Yes, it is important to use caution when handling and using a CSEL laser pointer. Never point the laser at anyone's eyes or any reflective surfaces. It is also recommended to wear protective eyewear when using high-powered laser pointers. Additionally, always follow the manufacturer's instructions and guidelines for safe use.

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