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WTB: 10 Watt Laser Power Meter

HydroSean

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Anyone have a laser power meter that can measure up to 10 Watts and want to sell me it? I looked all over the internet and the cheapest one was like $900. Does anyone know of one for around $200?
 



Alaskan

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Re: 10 Watt Laser Power Meter

Keep searching eBay one will turn up
 

paul1598419

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Re: 10 Watt Laser Power Meter

Can't you get the Ophir for $300.00? You'll need to set it up with two power supplies and a voltmeter readout. I think if you supply the sensor with a +12 and a -12 volts it will read over ten watts. Otherwise, one will eventually pop up on eBay if you look long enough.
 
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HydroSean

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Re: 10 Watt Laser Power Meter

Can't you get the Ophir for $300.00? You'll need to set it up with two power supplies and a voltmeter readout. I think if you supply the sensor with a +12 and a -12 volts it will read over ten watts. Otherwise, one will eventually pop up on eBay if you look long enough.
Thanks for the info, but the cheapest Ophir detector I found on their website was $800 :p

Unless you're talking about this
http://www.ebay.com/itm/like/121997543380?lpid=82&chn=ps&ul_noapp=true
 
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astralist

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Re: 10 Watt Laser Power Meter

Can't you get the Ophir for $300.00? You'll need to set it up with two power supplies and a voltmeter readout. I think if you supply the sensor with a +12 and a -12 volts it will read over ten watts. Otherwise, one will eventually pop up on eBay if you look long enough.
As far as i know from dissassembling the ophir head (which used internal amplifier), they're using 78L08 for the positive rail and 79L05 for the negative rail. Meaning the supply for the opamp inside is +8 and -5.
Thus the opamp will produce only about 7V output at very best (6.8 typical for opamp used in ophir: OP07C and AD648J).
If the meter head outputs 1V/W meaing you'll only get 6.8W reading max.
He can't get 10W+ reading unless searching for output constant lower than 1V/W.

Their max input voltage (usually +22 -22) comes from those regulator's maximum rating.


That is a great find actually.
If only i have unallocated funds right now, i'll buy all of them :eg:

btw here is also a good choice

If you want to setup LPM using those ophir head, you need to calculate the resolution you needed.

For 0.04V/W meaning you'll get only 400mV if measuring 10W laser, 40mV when measuring 1W laser.
Which yields 40mV/1000=0.04mV/mW or precisely 40uV per mW laser power.
So you need to use digital multimeter capable reading such small voltage, and not to mention that it needs to be very accurate.
 
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paul1598419

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Re: 10 Watt Laser Power Meter

Yeah I haven't actually even seen one (Ophir) personally and was going by bits of information culled from other's posts. Your explanation makes more sense to me from the LPMs I have seen and do have.
 
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ped

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Please put (WTB) in a "wanted" thread title in future, otherwise people will thing you're selling an item.

Ped
 

Alaskan

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What do you all think about using a non-polarized beam splitter cube for measuring a 10W laser with a 5 watt LPM? I'm thinking that would work if you knew the loss across the wavelengths the cube is used at.
 

diachi

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What do you all think about using a non-polarized beam splitter cube for measuring a 10W laser with a 5 watt LPM? I'm thinking that would work if you knew the loss across the wavelengths the cube is used at.

I'd just go for a 50/50 beam splitting cube/mirror for whatever wavelength you want to test. Actually, you could go 90/10 if you wanted - as long as you know how much is being split off. That way it won't care how the diode is orientated - with a PBS it will.
 

HydroSean

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I'd just go for a 50/50 beam splitting cube/mirror for whatever wavelength you want to test. Actually, you could go 90/10 if you wanted - as long as you know how much is being split off. That way it won't care how the diode is orientated - with a PBS it will.
oh hey that's a great idea! So just split it 50/50 and double the reading then? that might work, however with the NUBM44 the beam divergence is kind of hard to split right down the middle...
 

diachi

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oh hey that's a great idea! So just split it 50/50 and double the reading then? that might work, however with the NUBM44 the beam divergence is kind of hard to split right down the middle...
A 50/50 beam splitter is a mirror that passes 50% of the entire beams power and reflects the other 50% - it doesn't just slice the beam down the middle. ;) :beer: It's essentially a fancy partial mirror - same goes for the non-polarizing beam splitting cubes - they are just a cube instead of a "plate"... Which offers some different benefits over plates, see Edmunds page below for more on that.

Thorlabs has them: https://www.thorlabs.com/navigation.cfm?guide_id=18 - any type of beam splitter/sampler you could ever want.

Usual detailed explanation from Edmunds: http://www.edmundoptics.com/resources/application-notes/optics/what-are-beamsplitters/
 
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HydroSean

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A 50/50 beam splitter is a mirror that passes 50% of the entire beams power and reflects the other 50% - it doesn't just slice the beam down the middle. ;) :beer: It's essentially a fancy partial mirror - same goes for the non-polarizing beam splitting cubes - they are just a cube instead of a "plate"... Which offers some different benefits over plates, see Edmunds page below for more on that.

Thorlabs has them: https://www.thorlabs.com/navigation.cfm?guide_id=18 - any type of beam splitter/sampler you could ever want.

Usual detailed explanation from Edmunds: What are Beamsplitters?
hah oh wow I feel stupid, in my undergraduate studies we had a mirror on a motor that would chop the beam in rapid succession so we could do both fluorescence and phosphorescence spectroscopy at the same time. I guess that was a beam "chopper," not a splitter... That's what I've noticed about recently graduating and working in the industry, everyone does things differently. Thanks for the information, I am always about learning more and more :D
 
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Alaskan

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If you get a NON-polarized beam splitter cube try to find one with AR coating for the wavelength you are measuring to reduce the loss. If you buy a mirror from this guy on ebay, he really knows his stuff and can measure the loss for you so you can have an accurate reading:

bjomejag | eBay

Edit: I did some searching on his ebay store and found this 90/10% mirror which is good across the entire visible band plus some; from 350 to 850nm: http://www.ebay.com/itm/Optical-Filter-Neutral-Dichroic-90-Reflect-350-to-850nm-ND-1-0-Sputtered-50mm-/311653079080

Just measure the 10% beam, that way you could measure the output of a 10 watt laser with a 1 watt laser power meter. I'd also buy a holder for the mirror on a small stand of some kind, otherwise you will have a floppy mirror which could cause the beam to go where you don't want it to go.
 
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paul1598419

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Nice find, Alaskan. Thanks. That same seller has these in smaller sizes for less, too.
 
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HydroSean

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If you get a NON-polarized beam splitter cube try to find one with AR coating for the wavelength you are measuring to reduce the loss. If you buy a mirror from this guy on ebay, he really knows his stuff and can measure the loss for you so you can have an accurate reading:

bjomejag | eBay

Edit: I did some searching on his ebay store and found this 90/10% mirror which is good across the entire visible band plus some; from 350 to 850nm: Optical Filter Neutral Dichroic 90 Reflect 350 to 850nm ND 1 0 Sputtered 50mm | eBay

Just measure the 10% beam, that way you could measure the output of a 10 watt laser with a 1 watt laser power meter. I'd also buy a holder for the mirror on a small stand of some kind, otherwise you will have a floppy mirror which could cause the beam to go where you don't want it to go.
Hey great information :thanks:, I am going to do a lot more research on the matter and will probably end up getting one of these dichroic filters.
 
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astralist

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But, what happened if the reflected beam accidentally goes back through the diode? Though i'm not really sure, it will most likely "burn" the diode's die right? (Assuming that the measured lasers are a diode laser)
______________________________________________________________
I'm not responsible for any of your actions, but i just want to share my knowledge here:
Measuring 10W laser using 5W LPM (for example Ophir 20C-A-1-Y) is quite easy if you can do a soldering and desoldering:
  1. Open your 20C-A-1-Y without touching the trimmer/potentiometer
  2. Desolder the 78L08 regulator, replace with 78L12 for max 10.8W max reading.
  3. Keep your 78L08 as a means for backup.

The calibration will intact as long as the trimmer/pot is untouched.
This method is of course has a drawback, the initial offset will grow to 12/8 times from when you used 78L08.
But you can easily revert to 78L08 though.
You can also change 78L08 to 78L15 for 13.8W max reading with initial offset grows to 15/8 times from original.

But if you're in doubt with your soldering/desoldering ability please don't do these lol.
And please be wary of static electric as it will kill the IC inside. ;)
 




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