Hi everyone,
Very general question: I've got an upcoming project that uses a laser diode (450nm, 100mW) and I would like to detect its laser beam with some kind of (shielded) photodetector placed in a distance of 30-40cm from the laser diode. My goal is to generate a signal whenever the laser beam hits a certain position on an object in vertical direction.
Are there any comparable projects or hardware recommendations for this wavelength/distance?
Thank you in advance!
Post your laser diode datasheet, image, (or link).
I think any simple photodiode detects the 450nm laser diode.
Sure, it's this one: https://www.mouser.de/ProductDetail/ams-OSRAM/PLT5-450B?qs=P%252BGkiCIryJtXEw%252BMukmdsg%3D%3D&srsltid=AfmBOoqKt5gJ-V5b16umfQ8YkDZmGUDtWcODZ1x8n6hG418ilgnPiuzc
So I guess, for example, this common photodiode module (How to use a photodiode module | Canada Robotix) would do the job?
Tysm.
I have never tested this laser, but I believe this sensor will work.
Remember, the detector will also detect any reflections of the laser beam.
Exactly what do you mean by vertical direction.
At 40cm the LASER beam width is fairly wide along the major axis.
If you are hoping to detect scattered light from the 450 nm laser diode, a randomly chosen photodiode is unlikely to work well, if at all.
Most common photodiodes are maximally sensitive in near IR (800 to 1000 nm), and have very low response at 450 nm. A typical example is shown below.
Any that use a photoresistor, or for ease of use, you might consider the photoresistor module such as this one:
https://docs.sunfounder.com/projects/ultimate-sensor-kit/en/latest/components_basic/07-component_photoresistor.html
Details in the link.
To isolate them from ambient light, set them an inch or so inside a toilet paper tube (or something similar if you want to look fancier) and consider covering the end with vellum paper. Easy, inexpensive way to test out whatever you're trying to do.
Can confirm. I set up a green laser tripwire maze every Hallowe'en and thought as you did, that a photodiode module would be a good way to get nice, clean triggers.
I believe I even consulted with the helpers here and the discussion might have been like this one, can't quite recollect the details.
Anyway, me being me, I tried it out and nope, the photodiode did not work for the green test laser (part number unknown, I hack Festive Holiday Laser Light Projectors to get the laser beams, they operate at 12V and look really cool with a little fog to highlight them).
The laser beam actually travels through a cylindrical lens first, so I assume that it will look comparable to the one in the picture at 30-40cm(?).
I would like to give out some kind of signal when there's enough light in y-direction (in the middle), if that's somehow possible.
Also thank you for all information. I think I will try out different ways, especially a photodiode circuit more sensitive to 450nm and the LDR module! I also figured out that ambient light won't be a problem since the whole setup can be darkened completely.
I don't understand what you mean by that. You can buy sensors capable of counting single photons with reasonable efficiency.
If you told us more about this apparatus, you may get helpful answers. Diagrams or photos would help. What is the purpose and focal length of the cylindrical lens?
The whole purpose of the lens is to make it circular and that is far from circular.
Not very clear what you try to do...
Anyway, Vishay ambient light sensor like Tept4400 could be an option, maybe some optical filtering for higher wavelengths.
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