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10 Lasers, 1 Power Supply, plus dimming ??

lasersbee

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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...
Better to freak out now rather than paying fines
or doing time later...

Jerry
 

hakzaw1

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hmmm

Sad that you did all that work before asking for help here. But we see that a lot.

Funny to us (but of course not to you) is your choice of username. 'analog' is what you want for 'dimming' as TTL is ALWAYS full on or off---no dimming that really works. Analog laser/driver can allow from zero to full power w/o risking much. I am not a pro by any means but reading the great help you have been given, I think you can see that your 'cart' is before your 'horse' .

Many laws/ rules,etc are rarely enforced BUT that will have zero bearing our case on should you get into a 'legal' problem - and lately this enforcement , in USA especially, has stepped up. AFAIK Canada has been enforcing these laws more than the US for some time. I would need to be a LSO in order to export lasers to Canada... something that hardly anyone knows, but at the LSO class we were told that.

I do not want to add to your problems BUT when you have time-- combine any double posts into one using the 'edit' (copypasta) and delete one. This is no big deal BUT in time someone will 'call you out' for doubles.
Some of our 'best' members are in Canada. ( one of several reasons why completing your profile is so important.)
For example-- it has been a long time practice for members owning a LPM to meter other members lasers free of any charge.
IF you are looking for your own LPM I may be able to help --just PM me. ...good luck w/ your project---hak
 

paul1598419

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A little late to post this, but there are some drivers that DO have a PWM input and separate TTL inputs. It is true that one can use TTL to modulate a laser with PWM as long as the modulation frequency isn't exceeded and the peak of the pulse is +5 volts and the trough is 0 volts. My point being, you can buy drivers that have a PWM input.
 

analog56x

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hmmm

Sad that you did all that work before asking for help here. But we see that a lot.
yea, well, i had no idea about the legalities of lasers... i honestly thought they were 'fun toys' first, and 'tools' second. boy was i wrong... but now that i have seen the error of my ways, im doing something about it.

Funny to us (but of course not to you) is your choice of username. 'analog' is what you want for 'dimming' as TTL is ALWAYS full on or off---no dimming that really works. Analog laser/driver can allow from zero to full power w/o risking much. I am not a pro by any means but reading the great help you have been given, I think you can see that your 'cart' is before your 'horse' .
haha, ive had this username for the past thousand years... well, 11 years, but in internet time, its pretty much forever :p im very grateful for the information here that has been brought to my attention. id much rather know and do something beforehand, than not know, try to plead ignorance, and end up getting royally screwed. i have enough going on in my life right now, without having to worry about possibly going to jail, or heavy fines...

Many laws/ rules,etc are rarely enforced BUT that will have zero bearing our case on should you get into a 'legal' problem - and lately this enforcement , in USA especially, has stepped up. AFAIK Canada has been enforcing these laws more than the US for some time. I would need to be a LSO in order to export lasers to Canada... something that hardly anyone knows, but at the LSO class we were told that.

I do not want to add to your problems BUT when you have time-- combine any double posts into one using the 'edit' (copypasta) and delete one. This is no big deal BUT in time someone will 'call you out' for doubles.
Some of our 'best' members are in Canada. ( one of several reasons why completing your profile is so important.)
For example-- it has been a long time practice for members owning a LPM to meter other members lasers free of any charge.
IF you are looking for your own LPM I may be able to help --just PM me. ...good luck w/ your project---hak
i definitely want to continue my work with laser pointers, so i think a LPM is definitely in the cards for me...

and what happens if i 'get called out'? is there any ill effect, or is it just like 'friggin guy, always double posting... what a a-hole' kind of thing?

haha, cheers!
 

Encap

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yea, well, i had no idea about the legalities of lasers... i honestly thought they were 'fun toys' first, and 'tools' second. boy was i wrong... but now that i have seen the error of my ways, im doing something about it.

and what happens if i 'get called out'? is there any ill effect, or is it just like 'friggin guy, always double posting... what a a-hole' kind of thing?

haha, cheers!
Lasers. laser knowledge, and laser laws, rules, and regs + how to handle them are a world unto themselves---a complicated and voluminous one.

If you want to learn about laser safety and laws, rules and regulations--have a look at this excellent web site: Laser Pointer Safety - A comprehensive resource, for safe and responsible laser use

RE: double posting---double posts are annoying to look at/sift through--other than getting "called out" you will start accumulating negative reputation points--see the green bar under you name--if members give you negative rep points it goes red with negative numbers/reputation goes negative. Beyond that you may get a warning not to do it from one of the moderators or a sanction
 

analog56x

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A little late to post this, but there are some drivers that DO have a PWM input and separate TTL inputs. It is true that one can use TTL to modulate a laser with PWM as long as the modulation frequency isn't exceeded and the peak of the pulse is +5 volts and the trough is 0 volts. My point being, you can buy drivers that have a PWM input.
nice, i wonder if DTR's are capable of that... because its definitely a bonus feature :) thank you

Lasers. laser knowledge, and laser laws, rules, and regs + how to handle them are a world unto themselves---a complicated and voluminous one.

If you want to learn about laser safety and laws, rules and regulations--have a look at this excellent web site: Laser Pointer Safety - A comprehensive resource, for safe and responsible laser use
i will definitely be having a look into this. well... more than a look... if im going to continue working with lasers, i am going to have to have at the very least, a basic knowledge of safety and laws.

RE: double posting---double posts are annoying to look at/sift through--other than getting "called out" you will start accumulating negative reputation points--see the green bar under you name--if members give you negative rep points it goes red with negative numbers/reputation goes negative. Beyond that you may get a warning not to do it from one of the moderators or a sanction
ah, ok. ill go through and fix my mess haha

:beer:
 

paul1598419

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To the best of my knowledge, DTR's drivers don't have TTL inputs much less PWM inputs. They are very good CC drivers used mostly for handheld lasers. The are very small to be able to fit in the tight spaces needed for a handheld laser. If you want a driver with these options you will have to go elsewhere.
 

analog56x

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To the best of my knowledge, DTR's drivers don't have TTL inputs much less PWM inputs. They are very good CC drivers used mostly for handheld lasers. The are very small to be able to fit in the tight spaces needed for a handheld laser. If you want a driver with these options you will have to go elsewhere.
ok. i still need the compact size... or do i... i could run the driver module outside of the heatsink body... i did find some TTL drivers on some chinese website for a little over 3.00 a piece... i just figured DTR's would be WAY better quality than those... but we'll see what he says when he gets back.

im pretty sure these drivers are not PWN or TTL compatible, but they work... haha
 

analog56x

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High power blue/green laser light bright many miles or kilometers from the laser. High-powered handheld lasers and laser pointers are considered a danger to human health and safety.
im not aiming to build high powered lasers though... i want under 4mW... im looking for a little green dot on a screen to help with reference, not a solid beam that is weird to work with.

i fully understand high powered lasers can harm people, thats why im trying to avoid them for now :)
 

RB astro

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analog56x, ignore daniyko, I've banned him for spam advertising constantly his business links.

RB
 

analog56x

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analog56x, ignore daniyko, I've banned him for spam advertising constantly his business links.

RB
oh... ok... good to know... i kinda thought he had nothing to contribute to this discussion anyways, stating what i already knew, and not really even touching on the topic at hand...

cheers and :beer:
 

Cyparagon

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To re-cap, there are inherent differences in cheap crystals that account for the differences in output power you are seeing. You could try binning (buying many, and using only the few that have similar powers), but cheap DPSS tends to vary/wander in power with time and temperature anyway. There are DPSS modules with optical feedback that would always give the same power, but they tend to be harder to find and more expensive. Diode lasers are a better option if you want a matched power.

PWM drivers aren't necessary. These are clearly low-ish power devices, so a current limiting resistor in series with each laser diode would be cheaper, simpler, and smaller. You already have a constant voltage source (which is something most of the battery/portable oriented people here aren't used to), so use it to your advantage. With a properly calculated current-limiting resistor, each laser can be treated more like a "normal" load. Do you know how to select resistor values?

Diode lasers have a higher forward voltage than DPSS lasers. You'll want to use a 9V PSU, or perhaps a 12V if you use higher power resistors.

That's how I would do it, anyway. The diodes are going to be rather pricey in that quantity.
 
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analog56x

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To re-cap, there are inherent differences in cheap crystals that account for the differences in output power you are seeing. You could try binning (buying many, and using only the few that have similar powers), but cheap DPSS tends to vary/wander in power with time and temperature anyway. There are DPSS modules with optical feedback that would always give the same power, but they tend to be harder to find and more expensive. Diode lasers are a better option if you want a matched power.
yea, we've decided on the direct diode lasers for the next one. more of a matched result, like you said :)

PWM drivers aren't necessary. These are clearly low-ish power devices, so a current limiting resistor in series with each laser diode would be cheaper, simpler, and smaller. You already have a constant voltage source (which is something most of the battery/portable oriented people here aren't used to), so use it to your advantage. With a properly calculated current-limiting resistor, each laser can be treated more like a "normal" load. Do you know how to select resistor values?
i would like to use my PWM circuit so i can control the dimming, instead of having just 1 dimming mode... gives the end user way more control, and if my preset dimming is not dim enough, or too dim, i dont have to go in afterwards with a box full of resistors to tune them haha

and how do you mean select resistor values? im still pretty basic when it comes to electronics... ive got SO much stuff crammed in my brain, im surprised it hasnt exploded yet... but i i think i know the formula to figure out resistance required for a given voltage...

Diode lasers have a higher forward voltage than DPSS lasers. You'll want to use a 9V PSU, or perhaps a 12V if you use higher power resistors.
my power supply can run on 3.3, 5, 12, and 24 volts. quite versatile haha, being a ATX power supply, it has really good current capabilities as well... something like 28 amps at 5v... it is less with more voltage, but such is the nature of the beast. still way more than what these lasers draw...

That's how I would do it, anyway. The diodes are going to be rather pricey in that quantity.
that part is not really a concern haha, right now, im sitting on top of like 350$ worth of lasers :p didnt even blink when i told him we needed direct diode lasers that cost 65$ each.

thank you for your insight!
 

Cyparagon

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This is the configuration I'm referring to.





The current-limiting resistor for each laser diode is calculated via ohm's law.

(Vdd-Vf)/R=I

where I is the drive current in amperes, Vdd is the supply rail in volts, Vf is the forward voltage of the laser diode in volts, and R is the resistance in ohms. The power rating of the resistor is an important consideration, and should have a large margin... maybe twice the actual power dissipation. The power dissipated in watts by the resistor will be

P=(Vdd-Vf)*I
 

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analog56x

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This is the configuration I'm referring to.





The current-limiting resistor for each laser diode is calculated via ohm's law.

(Vdd-Vf)/R=I

where I is the drive current in amperes, Vdd is the supply rail in volts, Vf is the forward voltage of the laser diode in volts, and R is the resistance in ohms. The power rating of the resistor is an important consideration, and should have a large margin... maybe twice the actual power dissipation. The power dissipated in watts by the resistor will be

P=(Vdd-Vf)*I
interesting... a little more complex than i had originally thought, but not too bad...

am i going to need a variable power supply to figure out forward voltage? because i have no idea...

i think there are too many unknowns to figure out this equation...
i dont know the forward voltage, i have no idea what the drive current is, and i have no clue what the resistance is... is this for calculating the diode driver, or for what resistor i should add after the driver to get them the same?

(note: i am running on about 4 hours sleep, and havent had my caffeine fix yet haha)
 




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