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
 

FAQ: IR Laser diode focusing and module selection for CSEL Laser pointer

What factors should I consider when selecting an IR laser diode for a CSEL laser pointer?

When selecting an IR laser diode for a CSEL laser pointer, consider factors such as wavelength, power output, beam quality, efficiency, and thermal management. The wavelength should match your application requirements, while the power output should be sufficient for the intended use. Beam quality affects the focus and precision, and efficiency impacts the overall performance and battery life. Proper thermal management ensures stable operation and longevity of the diode.

How do I focus an IR laser diode for optimal performance?

To focus an IR laser diode for optimal performance, start by selecting an appropriate lens with the correct focal length for your application. Mount the lens securely in front of the diode and adjust the distance between the lens and the diode to achieve a sharp focus. Use a beam profiler or a target to verify the focus and make fine adjustments as needed. Ensure that the alignment is precise to maintain beam quality.

What are the safety precautions for using IR laser diodes in CSEL laser pointers?

IR laser diodes can be hazardous due to their invisible radiation. Always wear appropriate laser safety goggles that block IR wavelengths. Use the laser in a controlled environment and avoid pointing it at people or reflective surfaces. Ensure that the laser pointer has proper safety features such as a key switch or interlock. Follow all regulatory guidelines and safety standards for laser use.

How do I choose the right module for my IR laser diode?

Choosing the right module for your IR laser diode involves considering the diode's specifications, such as wavelength, power, and beam divergence. Ensure the module is compatible with the diode's electrical and thermal requirements. Look for modules with features like adjustable focus, heat sinking, and easy integration with your system. Compatibility with your power supply and control electronics is also crucial.

What are the common applications of IR laser diodes in CSEL laser pointers?

IR laser diodes in CSEL laser pointers are commonly used in applications such as communication systems, range finding, night vision illumination, and various sensing technologies. They are also employed in medical diagnostics, industrial inspection, and scientific research where precise, invisible light sources are required. The specific application will dictate the required specifications for the diode and module.

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