Spot Size measuring?

[Pierke]

Hello,

how can i measuring the spot size of my laser?

Pierke

[zax15uk]

Burn a hole in a piece of paper, use just enough power to produce a clean hole and ensure the beam is focused.

The next challenge is to measure the hole, a microscope with reticle would be ideal.

You can get pretty accurate results.

Zax.

[Litografa]

We measure spot size on Alumamark. With use of paper mark is slightly bigger than real spot size due paper burning. With Alumamark you have practically exact size of dot. Of course perfect focusing is necessary.

[zax15uk]

Actually the paper method with very low power produces accurate results when compared to electronic based measurement system. It even shows the halo or HAZ (heat affected zone) around the focused beam.

You will of course need a sufficiently high mag scope with measurement capability to determine the actual spot size vs. the halo area.

I have not tried Alumamark but that should work the same way, just with more power required.

Zax.

[Litografa]

And what do you think about glass or stone? Looks like on glass will be best results for accuracy of spot measurement?

[Pierke]

Heloo Litografa & Zax,

to measure the spot size, must i give only a short schot, or must i engraving a line?

Pierke

[Litografa]

I am using single shot.

[zax15uk]

Exactly - single shot.

It can be done by manually firing the laser at low power, just make the pulse as short as possible or if your system can send a single pulse from the software that is better.

Zax.

[kewlkiwi]

Cut a slot, and use feeler gauge set?

Bob

[zax15uk]

Originally Posted by kewlkiwi Cut a slot, and use feeler gauge set?

Bob,

That would work. I was trying to think of a simple way for someone to measure it without a scope or other equipment.

I have access to so much technology I couldn't see the 'simple' method.

Thanks,
Zax.

[Pierke]

Thanks to all for the verry good info.
I'm glad that i can try it on several ways.

Pierke

[MonoNeuron]

I just use a very powerful magnifying glass and measure the spot size with a dial caliper. It's accurate to about 0.0005".
I place a piece of thin cardboard bent over at 1 end to form a ramp about 10mm high and 50mm long then burn a spot every 5mm up the ramp. Then all I do is find out which spot is the smallest and measure that against the height from the lens to also get the focal distance for setting up the laser head.
regards
Richard.