10 Lasers, 1 Power Supply, plus dimming ??

Hello everyone, been stalking this forum for a while now for information, and have come across something that I cannot find any info about...

I am building a 10 laser assembly for use on set.
The requirements are:
10 green 5mW lasers
10 flexible arms allowing for independent positioning of each laser
dimming ability
1 switch to turn the assembly on/off

i have everything figured out and working, except for the dimming...

i built a PWM to adjust the brightness of the lasers, and it works, but it doesnt affect all the lasers the same... some dim before others, and one of them wont even reach full power.

the box i built plugs into 110v power, goes through a computer power supply, and outputs 5v. the supply positive is attached to the laser common positive rail, and the supply ground goes into my PWM circuit. i then have the negative output on the PWM going to the common ground rail for the lasers.

the resistance for each laser is the following:
#1 - 21.0k Ohms
#2 - 22.0k Ohms
#3 - 20.5k Ohms
#4 - 21.8k Ohms
#5 - 21.5k Ohms
#6 - 21.4k Ohms
#7 - 21.8k Ohms
#8 - 21.4k Ohms
#9 - 21.7k Ohms
#10 - 21.7k Ohms
Extra - 21.3k Ohms

the resistance was found through the ground point on the driver board, and the body positive.
the extra laser is my test laser, i use this one to test everything so that i dont risk damaging any of the ones i need.
Maybe im not measuring the resistance properly? maybe those values are way out to lunch?

i picked 2 lasers; the highest resistance, and the lowest resistance, and hooked them up to my PWM dimmer, and what surprised me was the lowest resistance one dimmed first... i then picked 2 lasers with the same resistance, and consistently one was favored for dimming before the other. it did not matter how i connected it to the common rails.
After this, I picked 2 lasers with a difference of resistance close to what i had a resistor for. I soldered the resistor onto the lower value driver, and tried to power it up, but it wouldnt even turn on...

i feel like i am finally stumped on this... for this project, a simple half bright level would be acceptable, but i just cannot get all the lasers to output the same power level. when i connect one laser up to the 5v directly, it is full brightness, and when i add my 5.6ohm custom resistor to the laser, it dims as near as i can tell to around half. when i pick another laser, and repeat this test, the effect the 5.6ohm resistor has is different... its not the same reduced power level.

these lasers are of an unknown brand, they are supposed to be wickedlasers nano, but i dont think they are, judging by the pictures i saw of the nano, and what i was presented with... also, there are no pots on the driver boards, so i have no idea how to fine tune them...

ive been toying with the idea of building my own drivers for these, so i can fine tune them, but at that point, i might as well just build my own lasers from scratch instead of buying expensive lasers... ill post some pics, and hopefully someone can offer some advice...

Well if you were stalking the forum for a while
you are aware that we ask all new members to
introduce themselves to the Forum members by
telling us a little about yourself...
It would also be helpful if you included your
Global location in your Member Profile.

Jerry

lasersbee said:

Well if you were stalking the forum for a while
you are aware that we ask all new members to
introduce themselves to the Forum members by
telling us a little about yourself...
It would also be helpful if you included your
Global location in your Member Profile.

Jerry

Click to expand...

Exactly

analog56x said:

Hello everyone, been stalking this forum for a while now for information, and have come across something that I cannot find any info about...

i have everything figured out and working, except for the dimming...

i feel like i am finally stumped on this...

these lasers are of an unknown brand, they are supposed to be wickedlasers nano, but i don't think they are, judging by the pictures i saw of the nano, and what i was presented with... also, there are no pots on the driver boards, so i have no idea how to fine tune them...

Click to expand...

The problem may be that you don't know what you are doing or why to begin with as regards DPSS lasers. They do not work the way you imagine.
You don't even know who made the modules or the output of each?

If they are 532nm green they are all going to be different because they are DPSS laser depend on an 808nm laser diode to pump a crystal system the converts it to 532nm---they will all do that in various efficiencies not directly dependent on/regardless of the power supply --is the nature of them. They will all be outputting IR a well. No way you can judge output level without a laser power meter anyway.
Without a proper heat sink for each, they will constantly change--getting dimmer and dimmer as the heat up and will suffer thermal runaway quickly in like 1 minute or less. Laser diodes are current not voltage regulated devices the divers supply the required current regulation not voltage regulation

see about the process here: https://en.wikipedia.org/wiki/Diode-pumped_solid-state_laser

Please make a Welcome thread in the Welcome subforum with something about yourself and indicate you location in your profile if you expect comment or held.

lasersbee said:

Well if you were stalking the forum for a while
you are aware that we ask all new members to
introduce themselves to the Forum members by
telling us a little about yourself...
It would also be helpful if you included your
Global location in your Member Profile.

Jerry

Click to expand...

done and done.

and i was stalking for information regarding what i was doing, checking out a few threads where guys had built their own driver modules, etc. never got THAT in depth. sorry.

Encap said:

The problem may be that you don't know what you are doing or why to begin with as regards DPSS lasers. They do not work the way you imagine.

Click to expand...

this is exactly why i am asking for help

Encap said:

You don't even know who made the modules or the output of each?

Click to expand...

correct. there were no identifying marks or labels on the lasers when i recieved them. the guy who hired me to build this laser device supplied the lasers. he got them from another company who had started to dismantle them for their own purposes. all i know is that they are green, emit a slightly visible beam at full power, and run happily on ~4v. they will run on as little as 2.8V and do run on 5V, but get warm after a few minutes. I have machined custom aluminum heat sink bodies for them, which keeps them at a stable temperature (tested for roughly 1.5 hours constant) where the heat sink is warm, but you can easily hold onto it without any discomfort whatsoever.

Encap said:

If they are 532nm green they are all going to be different because they are DPSS laser depend on an 808nm laser diode to pump a crystal system the converts it to 532nm---they will all do that in various efficiencies not directly dependent on/regardless of the power supply --is the nature of them. They will all be outputting IR a well. No way you can judge output level without a laser power meter anyway.
Without a proper heat sink for each, they will constantly change--getting dimmer and dimmer as the heat up and will suffer thermal runaway quickly in like 1 minute or less. The for the laser diodes are current not voltage regulated devices the divers supply the required current regulation not voltage regulation

see about the process here: https://en.wikipedia.org/wiki/Diode-pumped_solid-state_laser

Please make a Welcome thread in the Welcome subforum with something about yourself and indicate you location in your profile if you expect comment or held.

Click to expand...

if i am understanding you correctly, nothing i can do will get them to be the same...


overheating is not an issue just thought it would be more useful to show the laser outside of the heatsink i made

If you want to have the kind of control you are talking about, you need to use direct diode lasers and appropriate drivers. By appropriate, I mean ones with a PWM input. Then you can have the control you want.

paul1598419 said:

If you want to have the kind of control you are talking about, you need to use direct diode lasers and appropriate drivers. By appropriate, I mean ones with a PWM input. The you can have the control you want.

Click to expand...

THANK YOU!!!!

This ^^^ is the information i was looking for... so these unknown lasers that i have are not going to work. i will look into the Direct Diode lasers, and PWM drivers. I finally have a direction to go! Thank you!

analog56x said:

THANK YOU!!!!

This ^^^ is the information i was looking for... so these unknown lasers that i have are not going to work. i will look into the Direct Diode lasers, and PWM drivers. I finally have a direction to go! Thank you!

Click to expand...

Note, most suppliers don't refer to the modulation characteristics of the driver as PWM, TTL is the standard terminology for that sort of driver. Application wise it makes little difference, you can feed a PWM signal into a TTL driver, they're both just digital signals. The driver doesn't really care as long as your signal voltage is high enough and your pulse frequency is below the drivers maximum modulation rate.

You could also use a driver with analogue modulation, although those are typically more expensive and implementation can be a little more complex.

Not sure if it was mentioned, but read up on laser diode drivers and different types of lasers. That'll make things clear.

Feel free to reach out to me or post here if you have any specific questions. We're a friendly bunch here. :beer:

diachi said:

Note, most suppliers don't refer to the modulation characteristics of the driver as PWM, TTL is the standard terminology for that sort of driver. Application wise it makes little difference, you can feed a PWM signal into a TTL driver, they're both just digital signals. The driver doesn't really care as long as your signal voltage is high enough and your pulse frequency is below the drivers maximum modulation rate.

You could also use a driver with analogue modulation, although those are typically more expensive and implementation can be a little more complex.

Not sure if it was mentioned, but read up on laser diode drivers and different types of lasers. That'll make things clear.

Feel free to reach out to me or post here if you have any specific questions. We're a friendly bunch here. :beer:

Click to expand...

:beer: cheers! that is fantastic. ive looked up TTL diode drivers, and found some really cheap! now i just need to source the correct diode type, and i think ill be on my way to completing this project!

i just looked up DPSS to learn more about it, and when i was taking apart the lasers initially, to bypass the push button switch, i broke one. the diode legs snapped clean off. so i took it apart, and it looked nothing like the cutaway picture of a DPSS laser diode... maybe im mistaken, but is there a real major difference in the looks of a DPSS laser, vs a pure diode?





unless the image in that webpage is oversized to show what goes on inside it... under that lense is a brass C ring, which is glued in place on top of the main body. inside that main body, there is 2 very small, maybe 0.75mm sq crystal or glass looking rods (im trying to remember, as somehow that part is the ONLY part i cannot seem to find... must have grown legs) the aluminum heat sink housing threads onto the brass housing, and then has a black plastic housing with a lense that threads into the aluminum housing... maybe all together, this is a DPSS... it just doesnt look the same as the picture on that website...

analog56x said:

:beer: cheers! that is fantastic. ive looked up TTL diode drivers, and found some really cheap! now i just need to source the correct diode type, and i think ill be on my way to completing this project!

i just looked up DPSS to learn more about it, and when i was taking apart the lasers initially, to bypass the push button switch, i broke one. the diode legs snapped clean off. so i took it apart, and it looked nothing like the cutaway picture of a DPSS laser diode... maybe im mistaken, but is there a real major difference in the looks of a DPSS laser, vs a pure diode?





unless the image in that webpage is oversized to show what goes on inside it... under that lense is a brass C ring, which is glued in place on top of the main body. inside that main body, there is 2 very small, maybe 0.75mm sq crystal or glass looking rods (im trying to remember, as somehow that part is the ONLY part i cannot seem to find... must have grown legs) the aluminum heat sink housing threads onto the brass housing, and then has a black plastic housing with a lense that threads into the aluminum housing... maybe all together, this is a DPSS... it just doesnt look the same as the picture on that website...

Click to expand...

Make sure they are laser diode drivers and not LED drivers. Laser diodes require current regulated supplies and are very sensitive to any sort of output noise. LED drivers usually don't meet the requirements. LEDs are far less sensitive than laser diodes.

As for DPSS, that's definitely a DPSS laser in your pictures. The diagram you posted shows a design more typically used in high end DPSS modules, or older units.

Newer/cheap DPSS modules use bonded crystals and less optics (both crystals are attached directly together using optical adhesive).

This diagram is more accurate:



Yours most likely won't have the pump focusing lens, and likely doesn't have the IR filter, but other than that it's the same.

Be very careful with DPSS lasers, especially if you're opening them up. The IR pump laser is just about completely invisible to the human eye (even at 20 WATTS it only produces a very dim red spot, not even as bright as a cheap 1mW cat toy pointer). If you have one powered up and you can't see any laser light don't assume that there isn't any there. Even your typical $10 532nm 301 pointer from China likely has a 200-300mW pump diode, possibly more.

diachi said:

Make sure they are laser diode drivers and not LED drivers. Laser diodes require current regulated supplies and are very sensitive to any sort of output noise. LED drivers usually don't meet the requirements.

Click to expand...

anything online that i have compared these drivers to is different... all the LD drivers ive seen have pots on them to fine tune, these do not.

diachi said:

As for DPSS, that's definitely a DPSS laser in your pictures. The diagram you posted shows a design more typically used in high end DPSS modules, or older units.

Click to expand...

this could be mostly where my confusion is coming from haha!

diachi said:

Newer/cheap DPSS modules use bonded crystals and less optics (both crystals are attached directly together using optical adhesive).

This diagram is more accurate:

Click to expand...

yes, i definitely saw crystals. tiny little things, side by side directly in the path of the diode.

diachi said:

Yours won't have the pump focusing lens, and likely doesn't have the IR filter, but other than that it's the same.

Click to expand...

im 99% sure it doesnt have the IR cut filter. like i stated before, these lasers were acquired from another company who started dismantling them. i never got the battery sections, or the front cover. just half a housing, with threads on both ends, and the laser unit firmly pressed inside. unfortunately i had to destroy the housings trying to remove the lasers so i could bypass the momentary push button switch. once i got the lasers processed and fired up, i noticed they were getting a little warm and starting to fade within the first minute or two of being on in a 18*C room, so i set about machining some massive surface area heatsink bodies for them. shouldnt ever have an issue with them overheating haha! i did play with them outside in around 3*C weather, and was able to maintain a steady light output for around 30 minutes, then i got cold and went inside.
but yea, with these heatsinks i made, ive had the lasers on for 1.5-2 hours steady, and no heat issues. the heatsinks get warm, but you can hold them with no discomfort. you can even press them against your cheek and not feel uncomfortable.

but now, with having to change the key item in this project, i just REALLY hope that whatever i find fits inside these bodies i made haha! would be a damn shame if i couldnt use them...


****EDITED****

where do i even go about findind a decent laser diode supplier? ive found 532nm uses DPSS, and 520nm is a direct diode, but i cannot find any that are below 50mW and under 70$ each... i definitely dont want to burn anything, and if i could even not emit a visible beam, it would probably be beneficial, as this project will be used with a green screen on movie sets... might be a bit funky if there is a bright green beam running through the shot... (this is mostly the reason they need to be dimmable)

This is an LPF member that has a store and sells
good quality/low priced Laser related parts....

https://sites.google.com/site/dtrlpf/

This is were we get our Test Bed laser diodes
and modules.

Jerry

lasersbee said:

This is an LPF member that has a store and sells
good quality/low priced Laser related parts....

https://sites.google.com/site/dtrlpf/

This is were we get our Test Bed laser diodes
and modules.

Jerry

Click to expand...

Yea! I found his site early this morning (1am) after watching StyroPyro's youtube video on his high powered 520nm laser. Already emailed DTR about the project. Just gotta wait till he's back from vacation haha.

If all goes well, we'll need 200-250 lasers haha! Massive project. Just gotta hammer the kinks out of the prototype. But thats why its the prototype

Cheers and :beer:

analog56x said:

Yea! I found his site early this morning (1am) after watching StyroPyro's youtube video on his high powered 520nm laser. Already emailed DTR about the project. Just gotta wait till he's back from vacation haha.

If all goes well, we'll need 200-250 lasers haha! Massive project. Just gotta hammer the kinks out of the prototype. But thats why its the prototype

Cheers and :beer:

Click to expand...

Is hard to imagine or understand why anyone would hire someone who is not an expert in lasers---a non-professional with no knowledge of lasers or laser laws, rules, and regulation to put together 200-250 lasers--go figure? Canada and USA have very strict laser law, rules, and regulations.

There are a lot of details you have no idea about -- including any use in a workplace or "movie set" of a device that includes lasers--not the least of which is Canadian laws rules and regulations--unless you just want to be an outlaw doing illegally and take you chances.
There are many requirements you need to know. What you don't know can hurt you and other people as well.
If you attempt to sell or make available a portable laser which is Class 3B or higher--anything above 5mW output and saying you do not know the output is no excuse, Health Canada has an incredible array of powers to utilize against you, including product seizure, mandatory recall, huge fines, etc. Note, it doesn't need to be a sale. Giving one of these to your brother for free would be considered a violation.

You will need to but a Laser Power Meter to know what the output is---is a accurately measurable thing--not a daydream thing. You will need to consult a certified Laser Safety Officer (LSO)

Under Canadian laser laws, rules , and regulations--Lasers emitting accessible visible radiation with a power output of greater than 5 milliwatts (i.e. Class 3B and 4 levels) are prohibited.
See: https://www.canada.ca/en/health-canada/services/consumer-radiation/hand-held-lasers-laser-pointers.html
and
https://www.ccohs.ca/oshanswers/phys_agents/lasers.html


"Quick summary: As of June 2011, it is illegal to sell or provide high-powered portable lasers (Class 3B and Class 4) to consumers in Canada. That means you.

Before the inevitable discussion starts: It doesn't matter what you intend to use them for, or that you already have one, or whether you think that you're not a "consumer" because you think you're a "laser expert", hobbyist, inventor, or whatever. If you are not a scientist working in a laser lab at a University, or a CLSO, or an OEM which is integrating these lasers into other devices for commercial purposes, then you are a consumer. If your organization's primary activity does not involve high-powered lasers, then you are a consumer. If you do not have a clearly-defined commercial or academic requirement for a high-powered portable device, which cannot be fulfilled with a lower-powered or non-portable device, then you are a consumer. In fact, I'm going to go out on a limb here and say that, as far as Health Canada is concerned, every person on this forum is probably a consumer.

The actual regulation which was implemented in June 2011 is called the Canada Consumer Product Safety Act (CCPSA) and you can find the full mind-numbing legal document here: Canada Consumer Product Safety Act

Specifically, in Section 2 they define "danger to human health or safety”:
“danger to human health or safety” means any unreasonable hazard — existing or potential — that is posed by a consumer product during or as a result of its normal or foreseeable use and that may reasonably be expected to cause the death of an individual exposed to it or have an adverse effect on that individual’s health — including an injury — whether or not the death or adverse effect occurs immediately after the exposure to the hazard, and includes any exposure to a consumer product that may reasonably be expected to have a chronic adverse effect on human health."

See thread here: https://laserpointerforums.com/f44/canadian-restrictions-portable-lasers-official-info-release-laserglow-73129.html

Uh oh... ill bring this to his attention... i had no idea... thank you for letting me know! The last thing i want to do is get myself, or anyone else in trouble... damnit.

analog56x said:

Uh oh... ill bring this to his attention... i had no idea... thank you for letting me know! The last thing i want to do is get myself, or anyone else in trouble... damnit.

Click to expand...

You better look into it all carefully---is not just a matter of fun and daydreams about lasers and what might be done with them--there are real and enforced lasers laws rules and regulations---especially if they are going to be used outside of your basement exposing other people to them. Lots of Canada and USA laser equipment use, safety regulations, and law.

The authority in USA is US FDA
"FDA regulates all laser products, even handheld, battery-powered lasers that are available for purchase FROM manufacturers, importers, assemblers, dealers or distributors in the United States and its territories.
FDA requires that manufacturers of these lasers limit the power of the laser light to 5 milliWatts (often abbreviated as "mW") or less. "
From: https://www.fda.gov/AboutFDA/Transparency/Basics/ucm302664.htm

Also see: https://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/HomeBusinessandEntertainment/LaserProductsandInstruments/ucm116373.htm

Encap said:

You better look into it all carefully---is not just a matter of fun and daydreams about lasers and what might be done with them--there are real and enforced lasers laws rules and regulations---especially if they are going to be used outside of your basement exposing other people to them. Lots of Canada and USA laser equipment use, safety regulations, and law.

The authority in USA is US FDA
"FDA regulates all laser products, even handheld, battery-powered lasers that are available for purchase FROM manufacturers, importers, assemblers, dealers or distributors in the United States and its territories.
FDA requires that manufacturers of these lasers limit the power of the laser light to 5 milliWatts (often abbreviated as "mW") or less. "
From: https://www.fda.gov/AboutFDA/Transparency/Basics/ucm302664.htm

Also see: https://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/HomeBusinessandEntertainment/LaserProductsandInstruments/ucm116373.htm

Click to expand...

yea, ive let him know that i require a lasermeter if i am to finish this project.
so, my understanding of this, is that if the lasers are all under 4mW, then i am safe. i have so much going on right now, and now, with the legalities of this, im kinda freaking out...