Atlantis DIY Laser Power Meter

[jasonmrc]

It depends on what you think is expensive or cheap. $70 for a laser power meter is cheap in my book, but this is very limited in power handling, and i'm not sure about accuracy. It also is a retail price, i'm sure the total cost of parts for that meter are much lower than $70.

I think that the LPF commnity would mostly like to see a LPM that can handle more power, ideally up to 10 or 20 watts. It would be a challenge to find/build any affordable sensor that even survives that, but it's a goal that can be worked towards.

TEC's seem like a logical choice here since they are at least available at such power levels, but you cannot just point a 5 mW, 5 mm beam diameter laser at one, that will probably burn the surface.

What could work in my mind is getting the tec, and affixing a layer of anodized aluminium on the side that takes the laser light. This could be something the size of the tec, and perhaps 0.5 to 1 mm thick. This adds a LOT of thermal mass to the system, and the only way to get such a system to respond and acceptable speed is to use a power-following, unlit, identical tec heated by a resistor.

I'll be abroad for a well over a month from xmas and will not be able to do any practical work on this, but i could after. If you have any good options for the TEC or anodized aluminium material in mind i'd love to hear details.

Hi,

Actually i am using a .5mm sheet of copper and wrapped the resistors to it and glue it with thermal paste onto the tec ! As i said i need to conduct tests in the coming days !

 

[jasonmrc]

here is a simple design, i might include it in my design too ! the meter will have two ranges 1mw to 200mw and 50mw to 3 watts !

Circuit - LASER/LED LIGHT OUTPUT INTENSITY METER- Circuits designed by David A. Johnson, P.E.

 

[Benm]

Copper could be interesting, but that'd have to be coated with something black to absorb the laser light. I was actually considering black anodized aluminium because it has a very thermally resistant black finish as-is. It is not perfect, but perhaps that's something you could compensate for quite easily as long as it is equally reflective throughout the visible spectrum.

Especially for higher power application anodized my be better than painted - there is heat resistant coating/paint, but that has its limits, and could provide some problems in reproducibility of a project (it's hard to get the exact same thickness).

 

[Trendkilla254]

This is the cheapest option for low power: https://www.laserbeelpm.com/hlpm-ii.html
There are some LPM's specially designed for low power but they aren't cheap.

Alan

+rep!

 

[jasonmrc]

Copper could be interesting, but that'd have to be coated with something black to absorb the laser light. I was actually considering black anodized aluminium because it has a very thermally resistant black finish as-is. It is not perfect, but perhaps that's something you could compensate for quite easily as long as it is equally reflective throughout the visible spectrum.

Especially for higher power application anodized my be better than painted - there is heat resistant coating/paint, but that has its limits, and could provide some problems in reproducibility of a project (it's hard to get the exact same thickness).

Hi, yes copper is used in those expensive sensors, here;s a link about copper oxidizing i am studying.. shall try a sample soon.

Study and characterization of porous copper oxide produced by electrochemical anodization for radiometric heat absorber

 

[Benm]

Looks like something worth trying. I never realized that copper oxide is that black if you grow a decent layer of it. That article should help getting it right. I wonder how mechanically durable the oxide layer is, then again, it's something you don't need to regularly touch after installation.

 

[jasonmrc]

The issue now is to find some platinum ! i already started searching.. hard drive platters have some and harddrive heads too . worth a try

 

[Benm]

It's not really required i think. Platinum wire is often used in lab studies as it doesn't deteriorate and can be re-used many times for different experiments. For low current applications like this you could try a carbon rod, which is unlikely to react with the caustic solution. If it gives you trouble you can always look for some platinum (plated) wire, though it's fairly expensive.