How does one build a custom laser pointer?

[RedCowboy]

They have likely become better that when I last purchased a ready made, I typically build everything myself in the multi watt blue category and I even tore down some working 1-2w blues just to reuse the hosts as I had so many, I do have some freaky ndb7875 builds doing near 3W with a G3 lens that I still use but mostly I work with larger.........I do have some compact 1.5 - 2.xx watt units that I have saved, really if I was going to build one it would be a 7875 @ 2.4a, but I do have some NOS DTR 7875 diodes and some I bought from Rickers that were 0 hour pulls in my supply, don't know what's available in the marketplace as far as 0 hour but they wouldn't be cheap if true virgin........I think O-Like has some on ebay, maybe that new osram 3.5 will appear at some point, would be fun to check out.

----EDIT----

These claim to be new and show clean pins, you should be able to get at least 2.25w - 2.5w @ 2.4a from a 0 hour 7875 with a 3E or G3 lens, close to 3w with a G2 > https://www.ebay.com/itm/Brand-New-...h=item214ced5032:g:P78AAOSw9ipb97Jx:rk:6:pf:0

 

[VioletGiraffe]

These claim to be new and show clean pins, you should be able to get at least 2.25w - 2.5w @ 2.4a from a 0 hour 7875 with a 3E or G3 lens, close to 3w with a G2 > https://www.ebay.com/itm/Brand-New-...h=item214ced5032:g:P78AAOSw9ipb97Jx:rk:6:pf:0

Thanks for the link, they have many interesting diodes.
Do the ball lens diodes still require an external lens, or will the ball lens alone produce a nice collimated beam?

 

[GSS]

Gball diodes don't require another lens but are hit or miss as far as getting a nice colliminated beam and spot profile. Seams more of a miss though.
They can be decanned or the Gball removed but RedCowBoy experiences earlier diode failure. As they might have a inert type of gas when sealed. Red does though LOVE to drive them hard
You can somewhat tame a bad Gball spec beam with a added lens but you will lose some output power..
Hope he chimes in with his experience..

 

[Rune]

Hello guys
I am also very new to lasers. I would like to know what a laser driver does and how to find a driver for my needs (and where to buy drivers internationally). I would like to build a red laser at 200 Milliwatts but I don’t know what driver I need for that certain power. I anyone could tell me witch driver I need and the math and science behind I would be very happy!
Greetings Rune

 

[VioletGiraffe]

Hello guys
I am also very new to lasers. I would like to know what a laser driver does and how to find a driver for my needs (and where to buy drivers internationally). I would like to build a red laser at 200 Milliwatts but I don’t know what driver I need for that certain power. I anyone could tell me witch driver I need and the math and science behind I would be very happy!
Greetings Rune

The driver is of the current regulator type, it supplies constant current through the laser diode regardless of the input voltage or the characteristics of the diode itself (its internal resistance which will change with temperature, for example). The same kinds of drivers are used for LEDs (I mean non-laser diodes). Google for the datasheet for any particular laser diode model that you can get, the datasheet will list the maximum operating current, and maybe graphs like current versus output power. It will also list the forward voltage at that current; you'll need to make sure your input voltage is no less than that operating voltage + some margin, and that your driver is suitable for this voltage level. IIRC, red diodes operate in the 2.0-3.0 V range, so a Li-ion battery cell works perfectly as a voltage source. Then you just have to find an adjustable current driver for the required voltage and current (you'll pick output current based on the datasheet info and your desired power; for 200 mW optical power I guess it'll be around 400-800 mA).
I know that's only half the answer, hopefully someone else will expand on the topic.

 

[Rune]

The driver is of the current regulator type, it supplies constant current through the laser diode regardless of the input voltage or the characteristics of the diode itself (its internal resistance which will change with temperature, for example). The same kinds of drivers are used for LEDs (I mean non-laser diodes). Google for the datasheet for any particular laser diode model that you can get, the datasheet will list the maximum operating current, and maybe graphs like current versus output power. It will also list the forward voltage at that current; you'll need to make sure your input voltage is no less than that operating voltage + some margin, and that your driver is suitable for this voltage level. IIRC, red diodes operate in the 2.0-3.0 V range, so a Li-ion battery cell works perfectly as a voltage source. Then you just have to find an adjustable current driver for the required voltage and current (you'll pick output current based on the datasheet info and your desired power; for 200 mW optical power I guess it'll be around 400-800 mA).
I know that's only half the answer, hopefully someone else will expand on the topic.

I found a laser diode and driver both from Survival lasers. The diode is rated at maximum 500 mw. I think they fit together however, they don’t have the same voltage input range. Is that necessary that both the diode and driver have the same voltage range?
Here are the links so you can check if they fit together:

Here is the driver and I will set that to 1A
https://www.survivallaser.com/Survival_Laser_Fixed_Current_Driver/p556088_7425633.aspx

Here is the diode that can go up to 500 mw
https://www.survivallaser.com/DIY_635nm_Diode/p556088_6485617.aspx

 

[VioletGiraffe]

Of note: the diode seems to be rated up to 300 mW only as maximum continuous output power.
As for that driver + LD combination, I don't see a problem, it's rated 4.2 to 8.4 volts so it should have no problem producing ~2.6 V that the diode needs. Although I'd like to see more specs for the driver. Not sure why its minimum input voltage is so high.

 

[paul1598419]

They are just using the unloaded voltage of a single Li-ion cell as the minimum voltage. It is likely a buck driver which will work well at even high voltages above the Vf of the laser diode.

 

[VioletGiraffe]

They are just using the unloaded voltage of a single Li-ion cell as the minimum voltage. It is likely a buck driver which will work well at even high voltages above the Vf of the laser diode.

They indeed list is as a buck driver, and you're right, but personally, I would aim to run a 2.6 V diode off of one cell, not two, so I'm curious as to why the minimum input voltage is so high. Maybe I'm just spoiled by low-VDO linear regulators.

 

[paul1598419]

It is a simple mistake by whoever wrote the details of the driver. As soon as you put a load on the cell, the voltage will drop considerably, so the unloaded voltage really doesn't apply here. He just used the unloaded voltage of the cell as the minimum voltage.

 

[VioletGiraffe]

Well that's my thought exactly, if the driver's min. operating voltage is 4.2 then it's not suitable for running off just one cell.

 

[Rune]

Does the driver and diode then fit together so I don’t burn the diode? I have two 3,7 volts batteries and they will do the 4,2-8,4 volts for the driver input.

 

[VioletGiraffe]

You won't be able to burn the diode as long as output current is dialed in correctly on the driver (within the limits of what the diode can handle).
And, I guess, as long as you don't reverse polarity by accident.

 

[paul1598419]

With a buck driver you need only have enough headroom voltage for the drive to work. I would use two Li-ion batteries as that will ensure you have that headroom before one battery falls below that headroom.

 

[Rune]

I don’t understand what you guys are saying lol. I am just asking if you guys know if the diode fits together with the driver so I can get an output power of 200 mw or more and if two 3,7 volts batteries will be enough to power the whole thing.

 

[GSS]

Not sure what do you mean by fitting? The driver is usually directly soldered to the back of the diode pins and the diode itself is pressed into a module as it needs the module to absorb the heat or it will die bare. You can wire just the leads to diode/module and put the driver somewhere else depending on the build.
The driver is also set to the wanted current on a dummy test load, not when it already connected to the diode.
If you have seen those 12mm 532 modules, that's how they basicly look, or if you go to DTR's sales sight look at his diode sales and he will show setup pic's of the complete modules.