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Help me put together a laser test bench

MikeSD

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I started out on my project, looking for an IR laser of more power than what I can buy for my rifles. Then, got sucked into the whole laser field. ;) I'm an electrical engineer but have worked very little with lasers. So, in that regards I'm a total newbie.

I'm also of retirement age, so it could turn into a good hobby. ;)

One thing I really try to avoid is depending too much on others for specs and such. I also don't like reinventing the wheel, and do depend on others for things that are commonly known. For test data, I would prefer to do that myself.

So, I set out to build a basic laser test bench. The first thing I have found is it's taking more time than I want to spend, coming up to speed on what I might want in a bench. That's where you come in.

If you had, say $1000-$2000 to spend, what would you buy for such a bench? I would like to have ability to:

1) Test drivers and driver designs
2) Test raw laser diodes
3) Measure power output
4) Do some optical testing
5) Measure beam diameters and focal lengths
6) Measure diode wavelengths (if can be done reasonably cheap)
7) Are there any desktop optical benches that are cheap?

If this can be done for less than $1000 great. If not, then what is the driving cost I might eliminate. I'm not looking for a university optical lab, but I'm also not looking for a completely DIY, with pics and arduino. I'd prefer not to do too much building (i.e. designing boards and programming). I'm interested in the use of laser part and not so much at building test equipment. I'd prefer to just buy something and hook it up. ;) Something that's meant for direct readout of whatever I'm measuring.

I'm interested in the science of lasers; not the science of building test equipment. ;)

Suggestions?
 

diachi

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A half decent bench power supply with CC and CV would be a good idea, maybe two. I've also been looking at bench DMMs.

Your choice on LPM - The Radiants look good. I have a LaserBee and I like it, both are reasonably priced. Could pick up a more professional unit on eBay too - buying new would be outside of your budget for one of those though.

Check eBay for optical breadboards - they aren't cheap mind you - might find a deal though. You could make one yourself if you have the tools and the time.

For diode wavelengths you need a spectrometer. Again, not cheap, might be something you can get for a decent price used. You can also make a DIY one, of course it most likely wouldn't be as accurate as a commercial unit. To give you an idea of how much a new commercial unit can cost: http://www.edmundoptics.com/testing-detection/spectroscopy/ccd-based-fluorescence-spectrometer/86406/

For measuring beam diameters and focal lengths - cheapest solution is a set of digital calipers and a regular old steel rule. You can buy a beam profiler for measuring beam dimensions and quality but again, they really aren't cheap. http://www.edmundoptics.com/lasers/laser-measurement/laser-beam-analysis/coherent-lasercam-beam-profiler/2780
 

Pi R Squared

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If you had, say $1000-$2000 to spend, what would you buy for such a bench? I would like to have ability to:

1) Test drivers and driver designs
2) Test raw laser diodes
3) Measure power output
4) Do some optical testing
5) Measure beam diameters and focal lengths
6) Measure diode wavelengths (if can be done reasonably cheap)
7) Are there any desktop optical benches that are cheap?

I'm interested in the science of lasers; not the science of building test equipment. ;)

Suggestions?
Ok if you want an optical bench I suppose you want an optical table to go with that and some different optical components to go with those and you will quickly spend a few thousand dollars. So to keep it down to $1000 just concentrate on 1 through 5, forget about 6 and 7, and then later if you have lots of money to spend then think about 6 and 7. Your most expensive item will probably be the LPM.

Alan
 

MikeSD

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Forgot to mention, I already have

* Laser safety glasses (2 pair, 190-540 OD4, 190-540nm and 800-1700nm OD5)
* a DC Power supply, with CC and CV capability (0-30V, 0-3A)
* a DVM of course.
* soldering station

Ok if you want an optical bench I suppose you want an optical table to go with that and some different optical components to go with those and you will quickly spend a few thousand dollars. So to keep it down to $1000 just concentrate on 1 through 5, forget about 6 and 7, and then later if you have lots of money to spend then think about 6 and 7. Your most expensive item will probably be the LPM.

Alan
Actually, 6 and 7 were a last minute addition. I was initially only thinking 1 to 5. But that's usually what happens. When I start thinking of something, it guickly gets out of hand. ;)
 
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Pi R Squared

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For an LPM check out this site in Canada: https://www.laserbeelpm.com/home.html The cheap Radiant LPM I have is no longer available and wasn't very good anyway, the new Radiant will be much better but no telling when it will be available, it will also be USB only and require a computer, I prefer one with a built in display so I can take a quick measurement without bothering with the computer. When and if the new Radient becomes available it will be here: Illumn.com - Flashlights, Batteries, Carry Gear, Intelligent LED Lighting, and More! That is also a good site for a few other things, I have purchased from them a few times and so have many here.

Alan
 

Pman

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You can also keep a watch here in the Buy/sell/trade thread for a used Ophir based lpm. If you want to get into testing I'm sure you would like to catch the initial peak output reading rather than a slow response unit that takes many seconds to respond.
Your power supply will be fine for most diodes but there are diodes available now that 3A will not be enough. I have a 5A one but would actually like to upgrade.
The bottom line here is that you can start with what you already have but you do need the LPM and that's the one thing I would personally invest in. As mentioned buy one with a fast (as in a couple second) response time. I have 2 units and my first buy has a slow response time and is not accurate like my Ophir based one and I never use it. I keep it in case something goes wrong with my good one although I can't remember anyone posting Ophir based sensor issues.
Does Laserbee sell an Ophir based unit? I don't know who else sells an Ophir that is ready to go.

Just looked and their 7W Ophir based one is sold out:(

Here's their product page. Look at the response times to 100%:
https://www.laserbeelpm.com/products-1.html

Almost forgot. Welcome to the forum and there are some 50+ here (myself included). +REP
 
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paul1598419

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I've got a cheaper set up for testing the wavelength of lasers that is accurate and not difficult to set up. I'll post directions later on how to do this. You and I are of similar ages and backgrounds. +Rep to get you started.





Mike, here is a schematic of a diffraction grating used for measuring wavelength. d=slits in grating in meters. I have a large sheet that is 1000/mm. m= the principal maxima. If you measure the distance on the screen from the zeroth maxima to the first order maxima, and the distance from the grating to the screen is exactly 1 meter, the distance in mm is equal to the wavelength in nm. I won't insult you with the math to get from there to here, but I will include it in another post if anyone else is interested. If you send me a PM with your name and address, I will send you an envelope size piece of this diffraction grating free of charge. :D Paul
 
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