Kenom Laser Power Meter - Accuracy Test

Well, I caught this at the intermediate stage and got a stripped down version so it'd be easy to mail, so there's no pictures (no idea what the finished product looks like). Long story short though, Kenom is getting ready to offer a pretty exciting thermal meter based off of a real Coherent thermal head. I was interested in seeing how accurate it was so I begged and begged and finally got an evaluation unit.


I do have my gripes. It doesn't zero out on its own so you have to do a little basic arithmetic in your head. That minor frustration aside, I compared it to my calibrated Coherent Fieldmax II TO w/ PM3 sensor and was very impressed with the results. Of course the figures don't match up mW per mW, but there's a margin of error on everything from my power meter, to the laser sources. Overall though, they matched up pretty damn well - I daresay this Kenom meter is at least +/- 10% accuracy across 400-800nm, if not better. Comparisons were done with the following diode-based lasers instead of common DPSS sources like 532nm in the name of stability and to cover a decent spread of wavelengths:

- 405nm ~10mW DIY blu-ray laser
- Self-made TEC cooled 675nm fiber coupled >400mW laser
- >450mW 808nm pen laser


It matched up very well at 675nm and did well with 405nm. 808nm was the biggest difference, but even then we were only talking about 10-30mW or so on a 450mW unit.


Perhaps these tolerances aren't quite the stuff of your >$2k thermal meter, but considering Ken is going to be asking roughly a tenth of that, its one hell of a deal IMO. He's still working out the details as far as I know though, so I'll leave it to him to post the full features of this meter. All I know is that confronted with this or the LPM, I daresay I'd put a lot more faith in the thermal sensor of this Kenom meter. If you're on the market for a laser power meter, this is something to get excited about!

All the teasing around here, you guys are killing me! ;D I have a standing shoe-in for the next LPM-1 GB, but this may be more interesting? Can't wait for further details!

These are pending one thing and that's a computer connection for plotting runtimes.

other than that.  You can get a sneak peak at what this looks like!

Hey Kenom,

Have you thought of having the sensor head seperate? I know it would up the build a bit, but would that be a possible option?

Thanks!

it sure would.  it's pretty simple to remove the head and have it wired seperately. Although I'd prefer not to do this. it's more a matter of having to search for the connector on the board side and adding extra cabling could change the resistance of the wire and skew the reading results of the meter.

Yep, that was why I wondered if you would have an option for that, but obviously, it would need the connector-cable, head case and what have you as extra parts. No big issue there. Then it would need to be re-cal'd to accept the new resistance. So given all that, can you do it if needed? Or can you at least set up at purchase to reflect the differences for the external head and I can add the cable, etc. Would just need to know the specifics of what you used to base your program on so I build a similar contraption.

Thanks!

I sure would be interested in this and the price seems to be cheap! I'll be keeping my eyes open on more updates

ngiapy said:

I sure would be interested in this and the price seems to be cheap! I'll be keeping my eyes open on more updates

Click to expand...

Then you might want to check here, too.

http://www.laserpointerforums.com/forums/YaBB.pl?num=1200012124;start=all

I'm interested in this unit as reference or a "second opinion" to my twice as expensive little LaserCheck.

But I am quite skeptical (hoping I'm wrong) about its very wide range.
-How precise is it in 405nm low powered lasers? What is its most precise wavelength and power reading range (span)?
-Are they still available to buy on your site Kenom,and what do you get y ordering one?
I read it can be connected to computer software to print power output over time graph. Is this true, and is this option available.

thanks in advance

Milos

Milos said:

I'm interested in this unit as reference or a "second opinion" to my twice as expensive little LaserCheck.

But I am quite skeptical (hoping I'm wrong) about its very wide range.
-How precise is it in 405nm low powered lasers? What is its most precise wavelength and power reading range (span)?
-Are they still available to buy on your site Kenom,and what do you get y ordering one?
I read it can be connected to computer software to print power output over time graph. Is this true, and is this option available.

thanks in advance

Milos

Click to expand...

i have the circuit that is the heart of this unit - unlike the lasercheck the unit uses a thermal sensor to measure the heat output of the laser, not by the actual intensity of light itself, so as long as your laser is absorbed by the black material the sensor is made from it will give an accurate reading

Indeed.  This is wavelength independant.  Means as long as your shining a laser onto the sensor and the light is being absorbed by the treated material on the sensor it's going to show an accurate representation of laser power.  Now obviously some light Like IR is totally unaffected by certain colors.  However this seems to be pretty accurate all the way around.  I've tried it on bluray at 7mw and it seems to be dead on accurate.  without another meter of my own to compare to, there really is no way to be 100% sure but so far both lava, and pseudo have done testing on these meters and they have been very accurate.  I do still have one or two of these available and the boards are dissapearing quickly.  Here is a video of a few I put together.

What you see is what you get. It unfortunetly does NOT have the ability to graph straight out of the box. There is a way to do so however. I've purchased a digital multimeter with rs232 output that can easily be hooked up to this meter with a slight modification (which I've done to 3 meters so far) to allow easy connection to the multimeter. ONce the meter has been hooked up to both the LPM and the computer it's a matter of point shoot record. Here is a screen shot of one run I did



I can include the modified meter and the DMM for an additional $45.

Ok, that then means IR filter should be an accessory for testing green/blue/yellow DPSS pointers for the power of their green,blue, or yellow beams- respectively.

Thats great !
Thanks for the info. The range of the unit is very impressive. Price is unbeatable. I will be contacting you soon about one as I need to have ability to test my lasers 2 different ways.

kenom says my meter just got shipped!! I cant wait to measure all my lasers that ive had for 1-2 years . Ive had them for so long, and i dont know exactly how much they rate.

This is gonna be sweet. Thanks kenom.

I just got my meter, pictures and a first impression review are here:

http://www.laserpointerforums.com/forums/YaBB.pl?num=1204059317/0#0

ive heard this are great, if he makes another batch, i think ill buy one

I'm all for making another batch, but i've got to have enough interest to warrant purchasing some more boards. Currently I've got 2 possibly 3 people interested in one of these. If I get 2 more folks interested I'll go ahead and make some more.