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Thread: Noob question re. Laser Diodes and Required Optics

  1. #1
    Join Date
    May 2024
    Texas, USA

    Default Noob question re. Laser Diodes and Required Optics

    Hello All,

    I'm an IT Nerd that dabbles in electronics as a hobby, so please pardon the potentially 'stoopid' question!

    I'm working on a project that requires the use of a low-power ~650nM laser in the 5-10mW range, and I've hit a surprising wall in the quest to source a discrete component that I can drop onto a PCB that will work with minimal fuss. In fact, for the purposes of this post, assume Iím simply trying to build a low-cost laser pointer using discrete components from a quality/reliable source. Also, Iím not trying to do anything hyper critical (like measure distances, read/write data, cut material, etc.) Ė I merely want a bright red spot to be projected against a surface up to 25 yards away (unnecessarily expensive LDís & optics will be an overkill for my application).

    I use Mouser and Digikey for my component needs (I'm in the US) and there don't seem to be very many options for what I'm looking for (my first surprise). From what I can gather, this is what is available from Mouser, tho Digikey is pretty much the same: power=7 mW~~10 mW&rp=optoelectronics/lasers/laser-diodes|~Output Power

    I purchased a small batch of the cheapest options available ( to test, and was disappointed to see that the light output is very much dispersed into a dim approximately 2-3" circle from about the same distance away from the emitter. From what I have been able to glean online, it would appear I need to additionally figure out and acquire collimation and/or focusing lenses plus some kind of mechanical assembly to hold everything together.

    Is my understanding above correct? Is a turnkey pre-focused PCB mountable laser diode component simply not a 'thing'? (I really just want to drop a component onto a PCB that can project a bright red spot when driven)

    Assuming the above is correct, where can I get more information on the specifics of what I would need and where to acquire such hardware (in bulk)? It looks like the ROHM brand LDís are the most popular/available on Mouser and Digikey, and I have scoured the ROHM website for some kind of guides/application notes on this subject, but couldnít find anything of substance (they have great info on high-end applications like LIDAR & driver circuits, but nothing for my simple use case)? This makes me think Iím missing a fundamental piece of this puzzle Ė I would assume if a component needed supporting peripherals to be useful, the manufacturer would provide some kind of guidance in their datasheets or supplemental documentation? Also, wouldnít the likes of Mouser also sell the peripherals needed?

    The final point making me think Iím missing a fundamental piece of this puzzle is the fact that there appears (to me) to be a huge chasm between the cheap Amazon/Ali LD's and the 'high-end' Mouser/Digikey components - no middle ground? I can buy 20 (pre-focused) Laser Diodeís from Amazon for around $8.00 ( These work great for what I need, but I would never consider this as a serious production option (obvious concerns with quality and long-term supply). Were I to try creating one of these devices using parts I can reliably source Iím looking at costs of up to $30 ea. even using 'cheap' lenses and mechanical assemblies (the ROHM website does offer lenses, but these are approaching $100 ea.) I understand the Amazon components would easily classify as Ďcheap garbageí, but the price difference between $0.40c and $30.00+ ea. seems excessive?

    Any pointers you could give this noob would be greatly appreciated.


  2. #2
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    A lab with some dripping water on the floor.


    Your looking in the wrong place...

    DTR lasers,
    Power Technology Inc.

    Qui habet Christos, habet Vitam!
    I should have rented the space under my name for advertising.
    When I still could have...

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