WTB: Power Meter

[robotarmy]

Hey guys, I'm looking for a power meter to stick on the end of an ALC68b.

Used laserbee anyone? Do those have enough range be useful on a these lasers? apparently the things can push out a few watts at high enough tube current.

[buffo]

The laserbee tops out at 1 watt. You'd want something that goes up to at least 3 watts. (And to be honest, a really hot 68B could make 3.5 watts - at least for short periods of time...)

Your best bet would be to find a 5 to 10 watt thermal meter. That, or else buy a neutral-density filter... Then you could use a laserbee and just multiply your reading by the rating of the ND filter.

Adam

[robotarmy]

The laserbee tops out at 1 watt. You'd want something that goes up to at least 3 watts. (And to be honest, a really hot 68B could make 3.5 watts - at least for short periods of time...)

Your best bet would be to find a 5 to 10 watt thermal meter. That, or else buy a neutral-density filter... Then you could use a laserbee and just multiply your reading by the rating of the ND filter.

Adam

The big reason for me to get a power meter is for the UK's health and safety requirements.. A secondary justification for it is tuning up my laser, but really i want to be able to show due diligence and i guess a big part of that is having a power rating and a beam profile...

Would a ND filter allow the use of a cheaper meter but still be considered calibrated enough to satisfy health and safety regulations?

What about the use of a 95/5 split to send the beam to something like a webcam with the lens removed, to get beam profile and power rating at the same time, and borrowing/renting a laser power meter to put on the main beam to calibrate the camera's response?

[Doc]

If the meter is for measuring the laser power for show use you need something accurate in the sub 100mW range.

[robotarmy]

If the meter is for measuring the laser power for show use you need something accurate in the sub 100mW range.

sub-100mW? the laser can put out north of 2 watts apparently... I'm sure as shit not going to crowd scan at those kinds of levels but if i'm displaying it in public, even without crowd scanning, i should know what the power output is, right?

or were you talking about sub 100mW if i'm using ND filters/beamsplitters?

[Doc]

Yes, I meant if you were audience scanning.

My projector is 3W and used for audience scanning, but its the power density that matters, not the total power at the aperture.

Ian

[robotarmy]

Yes, I meant if you were audience scanning.

My projector is 3W and used for audience scanning, but its the power density that matters, not the total power at the aperture.

Ian

Wow! How do you keep it safe? attenuation maps? doesn't your scan angle have to be ridiculous to scan safely at that power unattenuated?

How do you determine power density?

[Doc]

Wow! How do you keep it safe? attenuation maps? doesn't your scan angle have to be ridiculous to scan safely at that power unattenuated?

How do you determine power density?

Basically it involves fitting an aperture equal to the average size of a dark adapted human pupil to the calorie meter head (7mm), recording the power, then using a formula to translate the power in to mW/cm^2.

Divergence is the main contributing variable.

(Short answer)

[robotarmy]

Basically it involves fitting an aperture equal to the average size of a dark adapted human pupil to the calorie meter head (7mm), recording the power, then using a formula to translate the power in to mW/cm^2.

Divergence is the main contributing variable.

(Short answer)

Right, i'm onto googling it

So, you put a calibrated (thermoelectric or optical?) sensor with a 7mm aperture on it, post-beam-table at some reasonable viewing distance, and run a typical show?

cool... now, what about for things like cleaning optics and walking in the mirrors on my argon? do i need TWO different power meters now?

Thanks for the help by the way man, it's all fun and games until someone loses an eye... am i missing something or is this board sorely in need of a laser safety forum?

[robotarmy]

Right, i'm onto googling it

So, you put a calibrated (thermoelectric or optical?) sensor with a 7mm aperture on it, post-beam-table at some reasonable viewing distance, and run a typical show?

cool... now, what about for things like cleaning optics and walking in the mirrors on my argon? do i need TWO different power meters now?

Thanks for the help by the way man, it's all fun and games until someone loses an eye... am i missing something or is this board sorely in need of a laser safety forum?

ooo n/m, just found the instructions in your MPE calc spreadsheet

nice one man, thanks for the tip for sure! are those calculations good by HS(G)95? I guess i'll have to have a good read...