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Review: Radiant Electronics Laser Power Meter!

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Okay, I haven't ever reviewed a LPM before, so I'll try and be as complete with my assessment as I possibly can be. I also don't have another LPM to compare to, so we'll see how it goes.

First off, I can't directly speak to the shipping time because for the past 3 weeks I've been traveling for work. This showed up while I was away, and I have no direct recollection of exactly when it DID come in. I do have a very faint remembering of it being pretty quick however.

The packaging was more than sufficient, and I was surprised as to how light it actually all was.

So far so good!

Let me start with some pictures.


This is what came in the packaging:





When I put the battery in, I did find that it was incredibly hard to get one of the terminals to fit, just because it was a brand new 9V connector and hadn't been "worn in" yet.



Looking at the top, we have the "Zero Adjust"

Basically, because the ambient room temperature can vary, you use the 0-adjust to make the LPM read 0 after leaving it on for a minute or two to acclimate to the room. Calibration and all that stuff.



Here it is, in all of it's glory with the power turned on and the zero-adjust set.




This is the actual thermopile with heatsink.





Overall construction seems really well done. It doesn't seem flimsy, I don't worry about putting it into the case with the rest of my laser odds and ends.

Now onto performance.

This was a hard one for me to measure, simply because I don't have a direct comparison for input, etc.

Here's what I can say:

It seems low. The outputs measured all seem quite a bit lower than other registered values I've seen in the past.

For example:

I have a 200mW green laser made by Sky Lasers. It's a PGL style gold one (some of you might remember, it's also linked in my signature)

Anyway, the measured output of that laser was around 250mW with a peak of 280mW.

On this LPM, that exact same laser has problems breaking 130mW after warming up.

Another laser I have, my oLike 300mW 650nm laser... It's rated at 300mW and most reviews I've seen to date suggest the exact same. I get maybe 210mW measured on the LPM.

In fact, just about every laser I measure is showing a vast lowering of what the suspected output power actually is.

Here's the question I have.

What are the procedures for PROPERLY LPM'ing a laser?

I took the oLike red laser and when I spread the beam out, the power level drops. When I focus it a little bit, the power level increases. (Makes sense, it's reading temperature)

So logically it seems that the beam should be a specific size for appropriate power output readings.

What is that size? How far away should the laser be? etc.

That all being said:

Here are more pics.








Overall impressions:

I love this thing. It's just very well built, (which is awesome considering it's made by hand) and I really do like the quality. It's not super "pretty" but it doesn't have to be. It's science folks! lol

The 2 disappointments are:The laser readings and the Zero-Adjust.

The readings: I really think I'm doing something wrong because there's *NO* way that my gold laser, which has been measured with an output of over 280mW isn't breaking 130mW. There's something very wrong there. (No it's not the batteries lol)

Also, when I LPM a 5mW pointer (various pointers that are all supposed to be 5mW or less) the meter doesn't even move. That's the only reason I suspect it might not be either as sensitive as I'm hoping or it's reading something incorrectly.

I don't blame the LPM yet though. I am willing to accept that everything else with the scenario is wrong first - mostly that I'm doing something incorrectly, but I'm curious to see what everyone else's thoughts are.

The Zero Adjust: What happens or where I have a problem is that the LPM always shows .001 (1mw) no matter how far I turn the zero adjust. I let it sit and acclimate for a few minutes (4 or 5) and it never actually quite makes it to 0. I have to sit it near a cold window to get it to drop to 0 properly, which drives me a little batty lol. (I'm totally OCD about it)

So those are my very minor gripes about it - nothing really wrong - again I could be mis-using it somehow, but from what I've read I don't believe I am.

As a side note, when I realized that this thing works off of heat, it turns out my thumb is 200mW.

Thought you would want to know ;-)
 
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anselm

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Nice review!

The problem with your readings is blatantly obvious:
It so cold in Canada, your lasers lose 1/4 of power before they reach the LPM!:D:D

Seriously though, that sucks.
You should have the seller replace or recalibrate it.
 

csshih

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The readings: I really think I'm doing something wrong because there's *NO* way that my gold laser, which has been measured with an output of over 280mW isn't breaking 130mW. There's something very wrong there. (No it's not the batteries lol)
au contraire...

how cold is it over there? how long did you leave the laser on? those lasers are very sensitive to cold..

see...



that there is a jetlasers 300mW PL-C, measured at over 400mW (and yes, I saw that rating shoot dramatically up after a few minutes..)
 

Trevor

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As a side note, when I realized that this thing works off of heat, it turns out my thumb is 200mW.
Never ever touch the surface of the sensor; it can damage the coating and/or the TEC plate itself and change your readings. :eek:

-Trevor
 
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Never ever touch the surface of the sensor; it can damage the coating and/or the TEC plate itself and change your readings. :eek:

-Trevor
Funny you mention that - I only did it for a couple seconds, and figured that what I was doing was probably NOT good in one form or another, so stopped.

Thanks for letting me know that for certain though.

About the LPM: It seems to have calmed down - When I was using it before, it was on the kitchen table, and while it IS cold up here, the lasers themselves all behave pretty consistently. The gold Skylasers doesn't ever get past 140mW at all, though on the flip side my two IQS #200's get 180mW consistently.

I still think there's something fishy going on, but when I used the laser power meter on carpet in my bedroom, it calibrates perfectly and gives seemingly more accurate readings. I guess I'll have to be very cautious of where I'm using it and what I'm using it on.

Interesting regardless.
 

Trevor

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About the LPM: It seems to have calmed down - When I was using it before, it was on the kitchen table, and while it IS cold up here, the lasers themselves all behave pretty consistently. The gold Skylasers doesn't ever get past 140mW at all, though on the flip side my two IQS #200's get 180mW consistently.
These lasers were measured by someone else in a different climate, correct? The only way I can see you being able to prove that the meter isn't calibrated right is to ship it to someone else who has another meter so that tests can be run with all other things held constant.

MarioMaster already did that, though.

I still think there's something fishy going on, but when I used the laser power meter on carpet in my bedroom, it calibrates perfectly and gives seemingly more accurate readings. I guess I'll have to be very cautious of where I'm using it and what I'm using it on.
A lot of things can affect readings, including ambient temperature and air currents. Try to let it equalize somewhere with still air that has an ambient temperature around 70-75F and run some tests there.

-Trevor
 
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Which one is built better, more accurate & reliable?
The Radiant Alpha or the 5 Watt Laser Power Meter by Nospin?
 

Trevor

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Unfortunately, I don't have $400 to get it.
Also, I have read about the Kenometer Pro mixed reviews on a different forum. (I bumped into by Google--> LH) So, I'm not sure...
With the new firmware that I'm developing (releasing soon, $30 upgrade), they'll be dead on accurate. :D

-Trevor
 
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Mine all seem low too compared to what some other people metered theirs at. Well except one I have. But then again it's possible that one is actually even higher than it's showing.

I did buy a 445 from yobresal. He LPM's all his lasers before they go out. To make sure they all are over at least 1 watt or they don't go out. And sells them as 1 - 1.2 watt lasers. I got mine and it measured 930mw on this LPM. He couldn't understand how that could be.
Hi,
Which LPM are you regarding to...the Radiant Alpha, the 5W LPM by Nospin or the Kenometer Pro?
 

Krogith

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Well the radiant alpha obviously since that is what this review is about and he was also having concerns about it being to low :)
Send me a PM if your in northern CA and we could meet up and test the meaters. I'd love to see if mine is running the same as yours... (This is my 1st LPM and sense he was rushing them out I wonder if maybe they were "Rushed" ) He did just barely get em out...
 

csshih

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an actual coherent thermopile (like what the kenometers and nospin meters use) retail for over 600 usd. one would assume they're more accurate than a TEC.
 
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Isn't that laser too close on ped's picture to the thermopile? It should by unfocused and away from the thermopile at least 6-7 inches.
 

MarioMaster

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I would like to see some testing where someone compares an alpha to a known good calibrated meter (IE a Coherent with a recent calibration) because although I've had reports of the meter reading low, I calibrate these with my Kenometer pro (which uses the Ophir thermopile). The Kenometer pro was verified accurate at SELEM 2010 when I compared it to some other members meters (Coherent units) using some big argon ion lasers.

I'm working my way to save for a Coherent FieldmaxII but I'm gonna need to sell a lot of Alphas if I ever plan on being able to afford one. It would be nice to ensure the absolute in accuracy for my customers.


If you are unsatisfied with your meter, you are welcome to send it back for a calibration check or refund.
 




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