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Suggestions for a power meter?

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Hi all,

I've been using high-end power meters for many years (Coherent mostly, $1.5K+), but I believe now there must be considerable competition from our friends over in China. Any recommendations for a low-cost power meter for relative measurements that would last 2-3 years? The wavelengths I am after are mostly 532 and 633-640 nm, power ranges are from 10 mW to 1000 mW, and beam sizes are 1 mm and up (of course I can insert an NDF, or expand the beam, or use a beam splitter cube and a rotating wave plate to attenuate if the beam is too strong). I mostly need one for relative measurements, as I have very good laser sources I could 'calibrate' against.

I found this:
https://www.laserbeelpm.com/laserbee-ax.html
...this
https://laserpointerstore.com/pocket-laser-power-meter
... and this
https://au.rs-online.com/web/p/power-meters/6278748/

Update: it appears that the laserbee unit might have the optimal ratio of quality/price, and the fact that the units are calibrated against a Cohernet PM helps.

It also appears that the response time is what one loses when going for a lower-cost PMs. I am quite spoiled with the quick Coherent PM response.

I could go for the RS-sold 40mW max unit (with the graph on the side), but I probably ruin it in no time with the power density.

P.S. Frankly, Coherent does not seem to see the writing on the wall with their pricing. No offense.
 
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Thanks! I just ordered their basic unit that has the 10-14s 90% response time, it should be sufficient to get me started. I wish I could go for the 3-4 sec response time one, but was not ready to spend $330 yet (plus shipping -- I am in the UK).
 

paul1598419

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You might also want to check out the Ophir power sensor that has been coupled to many different meters over the years, but it is the sensor itself that makes them all so accurate.
 
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I believe I have checked the Ophir sensors before (when looking for a professional grade one), and they appeared within the same price range as the Cohernet ones. Since I already know my local Coherent reps, it was easier at the time to get everything from Coherent and get a discount on a bulk order.
 

paul1598419

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I didn't know you could get a discount on the Coherent LPMs and that they were comparable in price. The Ophirs have been as low as $50.00 at one time and though they have been going up in price more recently, they could still be had for no more than $300.00 and can be setup to measure up to 20 watts.
 

lasersbee

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I didn't know you could get a discount on the Coherent LPMs and that they were comparable in price. The Ophirs have been as low as $50.00 at one time and though they have been going up in price more recently, they could still be had for no more than $300.00 and can be setup to measure up to 20 watts.
We've been doing some research on those OPHIR 20C
heads for a new project and the internal components
of the head are only rated for +/-18VDC.

The OHIR head can output a max reading of 18VDC
minus about 2.2VDC overhead or about 15.8 Watts
of reading at 1V/1W output.

The 20Watt rating would be more in line with a
0.4V or 0.1V/1W output wich the 20C heads are not.

Jerry
 

paul1598419

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Huh. That is different than many have posted here before now. Are you saying that the caps in them are rated at 20 VDC and, so shouldn't be used with higher voltages for that reason? Just trying to wrap my head around this.
 

Benm

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Another good choice could be the Hyperion series of lpm's, built by forum member Astralist.

I'm not sure if they are still available and in what varieties, but i certainly like the one i got.
 

paul1598419

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I heard not too long ago that astralist found another source for his TECs and would start making them again soon. I have his LPM with both the 6+ watt sensor and the 20 watt sensor. It is a fine LPM, especially for the money.
 

hakzaw1

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Rich do you have 8 LPMs (4 X 2)or was that an accidental double???
JKidding.
That happens to me a lot.. my fingers are 'tap-happy' My dial-up modem is to blame..
so S L O W...
Is there a place where I can change a setting to make my PC wait longer?? that is.. allow more time for loading before saying 'no internet' and know I am still on-line??
 

Lifetime17

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Hi,
I didn't even notice that Len , no only 4 I deleted one post buddy oops.

Rich:)
 

lasersbee

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Huh. That is different than many have posted here before now. Are you saying that the caps in them are rated at 20 VDC and, so shouldn't be used with higher voltages for that reason? Just trying to wrap my head around this.
It's not the passive components Paul... It's
the ratings of the OpAmps that limits the
Max Voltage you can apply to the OPHIR
heads.

Jerry
 

paul1598419

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It's not the passive components Paul... It's
the ratings of the OpAmps that limits the
Max Voltage you can apply to the OPHIR
heads.

Jerry
Is this for all the Ophir 20C heads or just the older ones? Seems like you could change the OP Amps out for higher rated ones if the ones used are limited to only 15.8 VDC. That seems to be even lower than Ophir claims for them. Did you find this in testing them or was this the rating for the OP Amps you found used in the heads you have now?
 

Benm

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I heard not too long ago that astralist found another source for his TECs and would start making them again soon. I have his LPM with both the 6+ watt sensor and the 20 watt sensor. It is a fine LPM, especially for the money.
Good to hear, the one i have is of excellent construction standard and would certainly be something i'd recommend in this price range.
 




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