Coherent Model 200 LPM - Help Reading {Pic Heavy}

What psychlosser said makes complete sense to me and I'm kind of kicking myself for not realizing that especially considering how many different kinds of meters I own.
Nice being able to switch the ranges but it will be nicer when you get your multimeter and see what you get for milliamp readings.
Can't help liking that old school look. Try to keep it looking nice. If it is working properly I bet there are plenty of members who would purchase this from you if you ever decide to sell it.
I really like the stand for the head too. I can't tell in the pic but does it change height?

That's What My initial Thoughts Were, But How TheN What Should I Make Of The Readings? Wouldn't They Be In The 30mW Range When I WAs Expecting 100+ And The 450 And 405 Ate The Only Two Readings That Make Sense?

Yes The Stand Is Height Adjustable. Believe It Or Not I Got It For $70 !

SorryButMyPhoneDoes This When I'm On The Forum.

473nm lasers are VERY unstable, they don't make a good benchmark. I would discard that from the data set.

Cool meter regardless...and 70$? not bad at all

$70 is amazing for that LPM, it was probably 20x that when new. Good score

ARG said:

473nm lasers are VERY unstable, they don't make a good benchmark. I would discard that from the data set.

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The 473 wasn't the only one that measured low though, the 532 also measured about that and while they are both DPSS the 520 that is set at 300mA should be reading in the 100mW range was also only hitting 30mW using the logic that Psychlosser suggested. Only it makes sense for my 450 and 405 readings.

Pman said:

What psychlosser said makes complete sense to me and I'm kind of kicking myself for not realizing that especially considering how many different kinds of meters I own.
Nice being able to switch the ranges but it will be nicer when you get your multimeter and see what you get for milliamp readings.
Can't help liking that old school look. Try to keep it looking nice. If it is working properly I bet there are plenty of members who would purchase this from you if you ever decide to sell it.
I really like the stand for the head too. I can't tell in the pic but does it change height?

Click to expand...

I should be getting a meter tomorrow so I'll have to read around on how to rig my head to the DMM. It came with a hard case with custom cut foam and in a box with foam that my cat has decided makes a great bed Not sure that I'll ever get rid of this one just because I love the way it looks. I might contact coherent to see if they can still calibrate these and if so how much they charge.

I didn't quote who asked about the case but here's how I got it:

Javalin said:

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Yup, nice case. You scored big time.

Regarding your readings, most of these diode pointers peak initially. then fall off and settle at a lower value. And at the bottom meter range, in the 0-300mW range, this meter will be the least accurate, IMO. I wouldn't bother getting it calibrated. It will likely cost you more than another $70 to do so. Did it come with an operations manual? Hunt the net for one and the system is complete.

See what I mean, I'm not the only one who really likes it.

Everyone with a cat knows that pic is a given

the multimeter hookup is simple. reality is that you just need the meter setup for mA and the probes in the correct holes and then just touch the probes to the 2 seperated metal pieces on the jack.

Okay, I got my DMM and I hooked it up to the end of the head. Okay, first I cycled the meter to mA THEN I hooked it up hit it with the 450 and nothing :wtf:

Any ideas?

I got a manual for it from coherent but it honestly didn't say much about it. At least nothing that I needed right now.

Edit: hooked it back up to the coherent model and it worked just fine.

Any chance of showing a pic of how you set it up with the meter?
Does the meter read properly for other things like voltages and resistance?

It seems to be reading other things just fine. Admittedly my list of known currents is very short, but I measured a couple lasers at the tail cap and it seemed to be reading okay. Does the head turn optical power into heat then into electrical current? I'll try to get some pictures.

I assumed that it was like any other head that I know of and just sent out a ma/Amp reading. Anyone ever seen anything different?

The jack does look like this right and you are touching the probes to either side of the black seperator?

That's it, I actually unscrewed the black piece and twisted a length of wire to each exposed post. I am getting V readings that might correspond to 10's of mW but nothing in the mA or A ranges. But even the V readings aren't making much sense. my 450 gives me .13mV then it will drop to .06mV most of my other lasers are giving me around .01 - .03mV

Edit: Not sure if it's just my computer, but I'm having trouble seeing all the pictures, each time I refresh it loads different ones...

Okay I got some pictures, First up is the connection to the plug. I unscrewed the black cover to get to the pins


Next up is the mA setting and the mA plug .000A


Now on the A setting .00A


Both settings again only this time in the A plug both .000A



Then I pulled the plug, switched the setting to mV

It starts out reading .12V almost instantly


But the output slowly drops over the course of about 30 seconds to .04mV


Am I setting it up incorrectly? The back of the head reads Calibrated 1MV/W but if that's the case then the rest of my lasers are reading around 10mW :thinking:

Have you called Coherent tech support to see if they can help you or get you a manual ?

They are you best for understanding what is going on and how to use.

You could also find out how much to have them look at it.

Ok, here's the deal. What an idiot. mV DC is what you should have your meter set too. Don't know how the mA got in my head. I woke up at 3AM this morning and couldn't get it out of my head and realized because of something else I was working on I kept saying mA rather than mV DC in the PM. Someone is embarrassed

Quickly moving on
From what I see you don't have your leads hooked up to the correct position on the meter or at least it seems that way from what I can see (can't tell for sure since the bottom of the meter is cut off in the pics I need to see). They should be black to black but the red should go to the far right one which is V/Ohms and Hz.
You should ALWAYS do a quick continuity test on the meter when you first power it on to make sure the leads are good and the meter is reading close to 0 ohms. Also, always change the position of the dial to the correct setting before taking a reading (obviously the leads too). Got to remember you haven't haad one before. That's a decent meter (think it's made by TPI for them).
Anyways, I can't see if your leads are in the far right positions when trying to read the DCmV but I am assuming they aren't (hoping too). This would explain the strange readings.
Does the meter beep when you have the leads in any other position then the far right when on mV DC? I don't know if other meters do this but my Flukes do to tell you it's not hooked up right for what you want to measure.