Stop Suffering -->LPM parts

[LSRFAQ]

Want something a little more professional then a home made absorber?:

https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=11777

This post brought to you by a laser professional who cringes at some of the home made LPMs he has seen.
Granted many hobbyist Peltier based systems are well made, but I've seen , evaluated, (and re-calibrated) some semi-production models that also really make me cringe.

Detector area not so great, 110$ is not that inexpensive, but a damn good coating , good minimum sensitivity, and good linearity.

Steve

 

[Cyparagon]

I'm with you. But the weird thing is people are fine spending 4-5 figures on pointers, but insist on the metering device being 2 figures. Ostensibly, a $50 device with a bad +/- 20% accuracy (which is incidentally quoted to 4 or 5 sig figs, as is customary here :thinking that looks like it got in a fight with a dull beaver is possibly a better value.

 

[LSRFAQ]

I pity the Beaver. No cellulose or plant fiber in a LPM.

LOL

However the cost of good, thermal, used, LPMs has shot thru the roof in the last year.
Due to the merger then buyout of major OEMs in the area, new price has shot up too.
Most LPMs I've seen on ebay, well the coating is shot from use in job shops with Q-switched fiber lasers and/or massive Co2 then dumped back on the used market. Either that or often marketed/selling at 75% of new cost. I spend a month on fleabay looking for lightly used heads for my home use. Nearly everything looked like it got in a fight with an A-10 piloted by an aggressive Beaver and lost.

One night I found a new OEM Ophir head with built in serial and analog . That solved the problem of finding a primary standard without a burned coating. At least for now. My Good Coherent Sensor has issues with a broken bond wire. I have VERY nice ones at work, but I do need to have decent ones at home. In my case, I have a few home made sensors with shop made coated carbon disks for tuning, but given my status in the community, and what I do, I'm expected, and do need to have traceable "Rocket Science" level instrumentation. Which ain't cheap anymore.

Steve

 

[Encap]

Want something a little more professional then a home made absorber?:

https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=11777

This post brought to you by a laser professional who cringes at some of the home made LPMs he has seen.
Granted many hobbyist Peltier based systems are well made, but I've seen , evaluated, (and re-calibrated) some semi-production models that also really make me cringe.

Detector area not so great, 110$ is not that inexpensive, but a damn good coating , good minimum sensitivity, and good linearity.

Steve

Good link ! +rep

I'm with you. But the weird thing is people are fine spending 4-5 figures on pointers, but insist on the metering device being 2 figures. Ostensibly, a $50 device with a bad +/- 20% accuracy (which is incidentally quoted to 4 or 5 sig figs, as is customary here :thinking that looks like it got in a fight with a dull beaver is possibly a better value.

LOL agree--they seem to gravitate to a cheap toy that displays number when hit with a laser beam as entertainment

 

[paul1598419]

Great link for anyone looking for a good sensor, LSRFAQ. Thanks for bringing it to the attention of people here. Your points are valid. + Rep.

 

[Alaskan]

Agreed, I didn't know these were available, nice.

 

[lasersbee]

Want something a little more professional then a home made absorber?:

https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=11777

This post brought to you by a laser professional who cringes at some of the home made LPMs he has seen.
Granted many hobbyist Peltier based systems are well made, but I've seen , evaluated, (and re-calibrated) some semi-production models that also really make me cringe.

Detector area not so great, 110$ is not that inexpensive, but a damn good coating , good minimum sensitivity, and good linearity.

Steve

Nice find.
I like the response time but for that $110 the
sensor size is a bit small at 2mm X 2mm (~0.079")
and can only handle 500mW.
For a more usable 10mm X 10mm it costs $327
and can handle 5 Watts.
Still a bit steep for a DIY LPM. You still need
low noise electronics since the output of the
sensor is low.

Still a lot cheaper than a new commercial LPM.

I'd go for the slightly larger and a bit less expensive
TD15A.

[Edit]
Reading some of the documentation it seems that
the sensor active area is damage sensitive to touch.
The info given is that the sensor coating is not to be
touched by bare skin or acid or base chemicals.


Jerry

 

[Alaskan]

darn...... well there goes my hope to use one of those for my lasers, nope.

 

[paul1598419]

The sensor could be recessed in a heat sink making touching the surface far less likely. If you want a good broadband surface, it will likely be a good idea to protect it against chemical and mechanical damage.

 

[LSRFAQ]

I will never knowingly touch the surface of a thermal sensor anyways. I do store them properly in a dustproof environment. Still a good absorber with a reasonably flat spectrum for those who play outside the visible. I hate the 3:1 markup, but still its a viable alternative.

Steve

 

[Alaskan]

Bought this instead of a full LPM, comments, suggestions?

https://m.ebay.com/itm/Coherent-J25LP-MB-1264-Laser-Sensor-Head/202285549340

E: I need for 1064 and ~980 nm.

Chris

 

[paul1598419]

It will depend on how the sensor face looks, Chris. Some of these have been well cared for. Others, not so much.

 

[LSRFAQ]

J25 is for fast pulsed lasers, just remember it will not see a CW laser in most cases.

https://edge.coherent.com/assets/pdf/EnergyMax-Sensors-User-Manual.pdf

http://zeus.phys.uconn.edu/wiki/images/Coherent_sensor.pdf

Had one at my last employer, really nice Joulemeter head.

If you do not have a Joulemeter to hook it to, you can usually read them with a fast oscilloscope.


Steve

 

[Alaskan]

I was planning on using my O'scope, it's specified to 200 MHz. I have a laser rangefinder I was hoping to find a way to measure the power output at 915 nm and needed a wide sensor to do that, so this will work for that, hoping this will also work for my SSY-1 YAG's, at 2J average power it far exceeds what my little YAG will do, but I'm not sure about the peak power, will research that further. I still need to find something to measure up to 25 watts CW at 980 nm.

Appreciate the help, thank you.

The MaxBlack energy probes J25LP-MB and J45LP-MB are well suited to measure laser pulse energy from 200uJ to 2J at rep rates to 1000pps for lasers across the spectrum - 0.19um to 11um. MaxBlack probes are designed to perform at fluency levels up to 265mJ/cm2 at 1064nm. According to Burt Mooney, director of sales for Coherent MolectronP: 'Thanks to our new, proprietary coating technology, the MaxBlack probes offer significant performance improvements over large-area, black-painted probes.

'They're faster, more sensitive, and more resistant to scratches and laser damage across the spectrum, yet they maintain the desirable features of black paint - including broad, flat spectral response, low reflectance, and good spatial uniformity.' Originally founded in 1985 Molectron Detector was acquired by Coherent in December 2002.

 

[hakzaw1]

cant rep anyone ATM but will later--great thread-needed info for sure..Thanx to all