Are these LPM numbers reasonable?

[Marco Polo]

I just received my Radiant X4 LPM today and have been metering my lasers. I'm honestly not sure about some of the readings. The lasers below are my C6 set, all of which are fitted with DTR modules with the current preset. Do these numbers look reasonable given the (supposed) currents involved?

All of them are using G2 lenses. The beams are defocused so that the spot is almost as wide as the LPM sensor, and the whole spot is landing on the sensor. Nothing is being clipped.

All batteries are freshly charged 18650 cells – 4.21 volts.

650nm single mode – 300mA – 218mW. Seems within expectations if it's an LPC840. It might be the LPC-826 though. It's the 650nm diode that is on DTR's website. According to him it comes from the BDR-206 sled. I have no idea.

638nm HL63603TG – 300mA – 188mW. Slightly low, maybe, but not by much. I'm not worried about it; it doesn't get warm when run for a while.

520nm PL520 - 300mA - 37mW. This can't be right.

450nm PL450B - 250mA - 260mW. This seems really high.

I can believe the readings for the red lasers but the PL520 looks completely off. Unless it's a really, really bad diode, it should be doing closer to 100mW at 300mA. I very slowly turned up the pot on it and it now reads 47mW and is noticeably brighter – the "Osram square" artifact is now visible, which it wasn't before. I just ran it for 5 minutes constant and the heatsink does not feel warm at all, it is still room temp. I feel like the current on this one must have been set low.

Not a huge deal if the PL520 was set low, it gives me an excuse to replace it with a PLP520B and transplant the PL520 to this slick Ehgemus host that is in need of a laser. I am just wondering.

The PL450B also looks way off; it shouldn't be doing more than 200mW at 250mA. My previous PL450B diode was supposedly set at 300mA and would feel quite warm after a few minutes of running. It died the LED death. This PL450B is supposedly set to 250mA and barely feels warm after a 5-minute run.

I'm going by the various power charts and whatnot that have been posted in questioning whether these readings are reasonable. How much cooldown time do I need to give it between tests? The readings are consistent when I re-test the same laser.

Are we sure the Radiant X4 is accurate? All of my Skylasers, except the HL520, are coming in substantially underspec.

 

[ARG]

Typically when an LPM is off it reads consistently high or consistently low, you seem to have a mix of both which makes me think that the readings are correct.

Are we sure the Radiant X4 is accurate? All of my Skylasers, except the HL520, are coming in substantially underspec.

They were calibrated with a NIST traceable coherent fieldmax. They are accurate.

 

[Shakenawake]

DTR does not have LPC diodes, I have asked him. these are easier to spot, they are open can

and yes, the 520 should be doing around 100mW @.3A, with a g lens. this is exactly the behavior and setting on mine. above 100mW by a bit for me, it's been one of my most trusty units, lasted a long time with no noticable degredation despite frequent use. one time i even accidentally turned it on without noticing in my pocket (with lens cap on). it might have been on as long as 10 minutes and is rock solid, not that I suggest trying this

 

[Blarg King]

I have a Radiant X4, and it's in line with the specifications of my lasers.
Perhaps yours is defective?-

 

[Marco Polo]

DTR does not have LPC diodes, I have asked him. these are easier to spot, they are open can

The 650nm diode I got from him is indeed open can. I don't think it's a long open can though. It comes from the BDR-206 sled but I don't know if that is the "designation" of the diode (per LPF convention of naming the diodes for the drives they're installed in). I have no idea what to call it, or what its output is "supposed" to be.

one time i even accidentally turned it on without noticing in my pocket (with lens cap on). it might have been on as long as 10 minutes and is rock solid, not that I suggest trying this

Already happened last weekend, battery was at 4.2 volts when I left the house and went to a RAtM cover show. When I left the bar I noticed the laser was on, with lenscap in place. Checked the voltage and it had pulled the cell down to 3.85. Never even got warm.

I think the PL520 diode in that case was set low because it handles excessive runtimes and doesn't warm up. It's a Microboost driver; isn't the current on that set by a combination of bridging the resistors on the board plus turning the adjuster pot to fine tune it? I don't think it's a multi-turn pot, is it? The highest I can imagine it going, given how far I turned it, would be 50mW at the very most. I wonder if it's just a weak diode but if it were being driven at 300+ mA you'd think it would heat up some, but it doesn't.

I could drop the PL520 in the Ehgemus momentary host as a 50mW and then install a PLP520B in the C6. Or maybe I can try the PL520 in a pen host or something like that.

I have a Radiant X4, and it's in line with the specifications of my lasers.
Perhaps yours is defective?

It was my initial thought but my HL520 50mW came in at 48mW so it is basically on spec. The HL63603TG is also close to spec per the power chart, it's within 10%. My Lazerer LZCS-PL450 came in at 145mW. Lazerer used a Laserbee to LPM it and it came in at 127mW; since Laserbees seem to read low (based on what I've read), this suggests that the Radiant X4 is working correctly. I think Skylaser/LaserBtB just sent me some underspec units.

The PL450B has me concerned though. I don't want to LED another one. Supposedly they are OK at 300mA but mine died. The power chart is for the PL450 80mW; the PL450B is advertised as 120mW. Were they revised and up-rated? Maybe it's just an efficient diode? It's doing 260mW which is very high for 250mA assuming the power chart applies to the PL450B as well as the original PL450. I feel like I should turn down the current on it a bit.

 

[bdgreenb]

Any room fans? Windows open? Breathing near the sensor? All of these can throw off readings. Sometimes I forget to turn off my ceiling fan and have a WTF moment before I face palm. I have an x4 as well. Also! I put my sensor on a piece of cardboard, if it's on something metal it will throw it off big time in my experience.

 

[DTR]

If you want you can shoot it over and we can compare the LPM reading I get on them them and confirm the current setting. Probably a good idea at this point. If you mean you just randomly turned the pot either up or down that is a bad idea. I would never suggest any method of changing the current on a boost or buck driver that does not involve removing the diode and putting the driver back on a test load. Keep in mind some pots reset so you may think you are turning it down when you end up kicking it up the the highest setting the driver is capable of. Also you run into issues of grounding out the pot or if running a diode while turning the pot there can be a spike. Just not a good idea to go turning the pots.

Anyway shoot me a message if you want to send them over to confirm.:beer:

 

[Marco Polo]

As much as I hate waiting on the snail mail I should probably just send it over.

The other thing I could do, since I would like to develop my skills a bit, is remove the dead PL450 from its Microboost and replace it with the PL520. The other Microboost was set at 300mA but who knows if it's still good. For all I know it's been killed by ESD now. I will have to power it up and see if the LED'd diode lights up but it probably wouldn't be any kind of guarantee, would it?

As for adjusting the pot, I adjusted it in small increments, and always with the battery removed from the unit. No adjustment with the battery in, or power on. I've read about how adjusting the pot can cause momentary disconnects as the slider moves, and that such things can cause big problems in the output current.

Will send you a PM when I am off work, thanks!

Any room fans? Windows open? Breathing near the sensor? All of these can throw off readings. Sometimes I forget to turn off my ceiling fan and have a WTF moment before I face palm. I have an x4 as well. Also! I put my sensor on a piece of cardboard, if it's on something metal it will throw it off big time in my experience.

Initially, but then I figured I should RTFM before going any farther. Would suck to break my LPM five minutes after removing it from the box. I set mine on one of my LaserBtB boxes. Once I shut off the window fan it behaved as expected. :beer:

 

[Marco Polo]

Thanks for all the advice everyone, I ended up sending in the PL520 and as long as I take the proper precautions I am getting consistent readings when I meter the same lasers at different times. It is definitely a change to be able to put actual numbers to my lasers' outputs.

Wouldn't mind having one of those Coherent Fieldmax LPM's though. Time to save up the ~1700 to 2000 bucks Except, it'll take forever because I'll just spend money on more lasers whenever I have enough. But at least I will be able to meter them :beer:

I'm still not sure about the PL450B though, is 260mW with a G2 lens normal at 250mA? It seems really high; I feel like I should dial down the current and bring it closer to 200mW. I don't want it to go the LED route like the first one.

 

[DTR]

Got it today. Your LPM is right got 36mW with the acrylic lens you were using. After testing the diode is fine but the driver is damaged and not regulating current. Good thing the the forward voltage of the diode is so much higher than a single Li-ion.

Anyway with a new driver set to 300mA it is now 87mW and probably over 100mW with a G-2.

 

[Rifter]

My PL450 also tested higher than I was expecting(edit, the 180mw posted in sig is with 3 element lens with a G2 it tests 220-230mw), I think the diode are just under rated or DTR got a really good batch.

EDIT #2, my PL450B is set to 200ma FYI, highest test was 226mw with authentic G2 lens.

 

[Marco Polo]

Got the PL520 back from DTR and hooked it up, and man that is way brighter than before. 110mW with the G2 lens and all it cost was a new driver. Thanks a lot for looking into it and taking care of it :beer:

I'm really curious about the PL450B though. I think blord's power graph might be outdated since it was the original PL450 at that time. The PL450B appears to be putting off ~43% more (at 200mA) and ~33% more (at 250mA). Since I have an LPM and will be getting a bench PSU soon, I'm thinking of getting a bare diode and do an updated power/current test. Should be interesting.