Laser diode of power 50mW

I want to buy a laser diode of 50mW for a project. I also want them in my budget and reliable. Anyone has idea on laser manufacturers of my requirement?

For eleven bucks, Amazon has your back.

More details on your “project” would be helpful.

Hello sir, I need a green laser diode with minimum possible beam divergence (in both major & minor axes) with an elliptical spot. I also want the dimensions of the spot. Thank you.

What are your requirements for the divergence?

Conversely, what is the required spot size at a specific working distance, because that can determine the divergence.

More details on your “project” will be helpful.

I want the divergence to be less than 15 degrees, working distance is 0.5m. I am working on creating a light sheet for a low cost PIV with decent performance.

That seems extremely large for a diode laser module, because typical divergences are measured in milliradians.

At half a meter, the spot will be on the order of 140 mm diameter, although the beam shape will certainly affect one dimension.

This seems to contradict your initial mention of “minimum possible beam divergence”.

What does PIV stand for in this context?

A “light sheet” seems to contradict the need for a “spot”.

How are you measuring “performance”?

Possibly Particle image velocimetry.

But curious how this fits in with LightBurn.

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This doesn’t seem to be related to LightBurn but, I can’t think of a better community to find bright enthusiasts that might be willing to contribute.

I’ll allow it for now and follow this closely. If it turns spammy I’ll blow it out.

I am new to this field so i am trying all the possible ways to get a idea on it. I want to know only about the laser diode which can meet my preferences. If anyone knows about the laserdiode I want to know about the vendor and price of it.

So far, your preferences seem to be contradictory, so it’s not clear what information you need.

Describe what you’re trying to accomplish and how the laser fits into that overall project.

Prying information out of you, one nugget at a time, will quickly become not worth the effort, as shown by the last several questions I’ve asked and you have yet to answer.

Help us help you, OK?

Thank you for the reply sir. I completely dont know the preferences. As of now I found a laser which looks close to what I need
Could you please give me some time so that I can discuss with my project guide and give you all the details by tomorrow. Thank you for your cooperation. Sorry if I took too much time.

You do realize that the laser you selected has a typical supply voltage of 5.8V.


Good day. Apologies for the confusion. Let me clarify

PIV stands for Particle Image Velocimetry, which is a technique used for visualization and quantitative measurement of fluid flow field in 2 dimensions.
I am trying to build a low cost PIV system with diode (green) laser and a cylindrical lens. The green laser beam from laser passes through the cylindrical lens, forming a light sheet downstream of the lens. The light sheet should (ideally) expand at a low angle of 15 to 20deg. The thickness of the laser sheet (i.e. measured in normal direction to plane of light sheet) should as low as possible until 1 m distance from the lens.

I found a few diode lasers in the market, but want to choose the correct candidate. The problem with available diode lasers is that they do not have all the specifications that I am looking for. For example, here is the OSRAM diode laser which i sent the datasheet in the previous post. They do not have the spot size mentioned in their specifications. Similarly, I am not even sure if the beam cross-section shape is circular or elliptical! Through this forum I was hoping to find how good this laser is and to find some answers to my questions.

As you mentioned, I want to keep laser beam divergence as small as possible (milli radians or even lower). But I do not know which laser to choose……Any help will be appreciated.
I am preferably looking for a 50 mw or larger green diode laser for my PIV application. Many thanks in advance. Please let me know if you need any additional details.

My understanding is that the spot of a dpssl is the same shape as the die used… Which is usually square or rectangular…

Usually when you vary from the typical manufacturing, your costs go up substantially.

Are you planning to build the electronics to support it or is the idea to just plug it in to some kind of controller?

I’d also suggest using a site like

Lots of people doing strange things… Lots of knowledge… especially at this level.

People on both sites would be interested in your project as many of our machines require a coolant and we monitor that…

I’m not familiar with the process. For those of us with curiosity, would you have a link that sketches out what’s happening and what sensor you may use?


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That’s because the package does not include a lens. The divergence specs tell you the beam shape before it hits your lens and also constrains the lens size.

Because that’s a bare diode, you must drive it with a very carefully controlled current source that does not exceed the specs even during startup, when cheap / crude drivers tend to glitch.

The rated 50 mW output requires a case temperature of 25 °C, which will probably require a husky heatsink and active cooling, because the diode dissipates about 1 W in normal operation.

IMO, you will be better off buying a commercial light sheet source with a simple power connection, because getting all the details right for a bare diode driver is difficult. It can be done, but it seems like a major distraction from the overall purpose of your project.


As a BEng Mech and a diyholic, I’d start here:

Didn’t go through 'em, but I’d assume that there’s a wealth of relevant information to get You started.

What little I do remember about PIV from my Poly days, the light source is by far the least of Your worries.
And also pretty much the cheapest as well.
Since sourcing the laser is especially nowadays far easier than sourcing the pair of lenses You’ll need, I’d recommend on focusing on those first, and then choosing the laser that suit the lenses.

While green laser does look very nice and is obviously visible to the naked eye, unless the intended application requires the particles to be visible for some reason, I’d choose a wavelength that suits the medium to be observed and/or the camera best.



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Dear sir,
Thank you so much for the reply and details. Oh it is a bare diode, now it is clear.
Could you please guide me on picking a suitable lens for this bare diode. Could you please help me with finding the right lens for this bare diode. Many thanks in advance.

Also thank you for the suggestions on cooling. Yes, I was anyway planning to put a heat sink. I will work on this carefully and will keep you posted.

The problem with commercial light sheet generator is that -
(1) they are expensive, (2) I want to move towards self assembly which will help me to (eventually) design a setup customized to my experimental needed. I believe that designing this from scratch will eventually help me with my experiments - I am exploring this option, hopefully I should succeed in my quest. I will keep you posted on my progress through this forum. Again many thanks for the help.

Thanks for the Info sir

You need far more information than can be conveyed through a forum intended to support LightBurn’s software.

I cannot become your unpaid engineering tutor, but it’s surely possible for you to study and learn all the subjects required to make progress on your project.

Good luck on your quest …


You’re welcome.

I wholeheartedly do agree with @ednisley, this forum is most likely not the best place to seek information about low cost PIV.
Or any other low cost very specialized DIY scientific equipment for that matter.
PIV among a plethora of other measuring methods has very narrow (if any) uses outside scientifical data collecting, so it’s very unlikely someone does it as a hobby :wink: .

We didn’t study fluid mechanics at PIV level, so that was just mentioned along other “non invasive” measuring methods, and we did a short brainstorming about the possible requirements for such a system.
A laser level (just like in one of the Google links on my post above) was actually mentioned :grinning: .

Granted, we are a diverse bunch of people with diverse skillsets and educational as well as professional backgrounds here, but since this forum is primarily intended for discussions about Light Burn CAD/CAM software for marking/engraving/cutting lasers, there’s most likely not much common ground with PIV laser heads or -optics.
Or any other laser applications for that matter.
So it’s unlkely that anyone here will -or even can- give You a pre-chewed answer for Your question(s), especially since You seem to be reluctant to even reveal what it’ll be used for.
Not to mention the budget.
So You just have to do the legwork Yourself.

If my hunch is correct and this is for an advanced educational project, You are also supposed to do the legwork Yourself.
Educationalwise, learning how to collecti and filter the information and putting it together is at least as important as the piece of equipment that’s hopefully the end result.

I did quickly skim through a few of the links on that Google search I posted in my last reply, and most had at least rudimentry BOM and even some cost calculations (as it should be on any DIY instructions).
Some of the papers and instructions are ~decade old so some of the equipment may not be available anymore and at least the prices (and availabilities) have changed, but reading through those will give You at least some idea what to do next.

The same from me.