My introduction, my first laser project, and a few questions.

Hello there LPF members! Chaz here. Thanks for having me!! I was referred here by DTR's laser shop. I decided to start a laser build after being interested in lasers for a long time. Long story short, I always had admired the Wicked Lasers S3 line and ordered one last year. A 2w+ Arctic to be precise. After several months with no product and no updates, I begrudgingly cancelled my purchase. I didn't think I would ever end up getting a laser, but after seeing many youtube videos and finding online shops, I decided to build one. I do have a considerable amount of experience with electronics, soldering, and high powered LEDs.

As a hobby, I occasionally build very expensive and very realistic Lightsaber props. We are talking the fully illuminated ones made of machined aluminum and running Cree or Luxeon LEDs up to 12w. I have one saber that I custom designed and assembled over five months and runs a triple Cree RGB LED wide open for full color mixing. It has sound, all kinds of FX, and a computer board that allows me to plug it into my Mac and change settings and all kinds of stuff on the fly. I had to make a custom 2x 18650 for that bad boy as it sucks 2.5A all the time, with bursts up to (and sometimes exceeding) 3A. Here is a link to the project and pictures if you wish to see them. I am not attempting to brag, just give a bit of background.
"Creed, Blade of Harmony" UPDATED WITH PICS!!! | Imperial Royal Arms
Although, to brag a bit I guess, if you were to commission a saber with the same level of detail and features from one of the career builders, it would cost well over $3,000. I simply build them for my own pleasure. Anywhoo, not relevant here.

I shared that to mainly shed light on the project I am starting. I recently purchased an NDB7875 445nm laser diode (Nichia?) with G2 lens and driver from DTR. As I understand, it is rated up to 3W with the 2.4 amp driver that I also purchased. Probably totally STUPID for me to be starting with such a death ray of a laser, but I have no excuse. I have always been an all or nothing type. I am having a custom copper heatsink made so that I can incorporate the laser into my host of choice... A custom machined Lightsaber body, since I have a heaping pile of spare parts laying around. It isn't going to be ridiculously fancy, but, its going to look like a Lightsaber. Mildly fancy. It should be a very cool host. I will be sure to post build pictures and the final product on here when it is done. The main activation is going to be a 16mm Anti vandal switch (my fav for sabers).

All that being said, I am a hobbyist at heart, but by day I work 911 as a full time Paramedic. Safety and preventing injury is very important to me. I always knew lasers were very dangerous, but it really hit me after I ordered the thing. Had that "what the heck am I doing" moment after reading a bunch of stuff about lasers and eye injuries. Scary stuff. *winces*

So that brings me to a few questions. Please forgive me if I am resurrecting dead threads. I did actually look through the archives here for a good while, and learned a lot. Especially about eye injuries... *winces again*

1. Can anyone recommend a high quality pair of glasses for such a powerful laser? I see a lot online, I just want to do it right the first time, and not end up with junky glasses. I am a gear snob. Guilty. I plan to get several pairs and hand them to anyone around me when using my laser. Damaging my eyes is bad enough, hurting someone else would be so terrible I cannot even imagine...

2. I can't get a straight answer online... Is it safe to view the beam for a moment without glasses? As in take it outside and point it at the sky or a tree, and view the beam itself as it passes by me? I know ANY reflections or viewing of the spot is a big NO NO. Just had to ask as I hear the blues above 1W have beautiful and visible beams, and I also hear viewing them with glasses makes it very hard to see the beam at all. Both of those statements could be totally false, as I have never seen a laser above 100mw in person.

3. More of an inquiry. I want to incorporate a secondary safety circuit, namely a key switch, into the build. I plan to hide the key switch under the pommel. I am looking for a nice Anti Vandal style key switch that is rated for the current this thing would require. Preferably something compact-ish that would make it easier for me to fit it into the build and minimize the amount of "kram-fu" I have to exercise. Do any of you know of a specific switch or place where I can get one? I see a lot of chinese supply websites but ordering just one isn't an option.

4. Battery... That diode needs between 6v and 9v according to DTR. I have a protected rechargeable Li-ion 7.4v pack made of two 18650 cells, 2600mah. Go or No-Go?

5. Recharge port. I use these on my sabers and wire them in a way that all power is cut off when charging or when a nylon "kill key" is inserted. Kind of a reverse of the way some of the safety dongles that I have seen for lasers work. Kill key out, activation switch is live. Kill key in, dead device. I can't think of a specific reason why I shouldn't use an in-body recharge setup without removable batteries, but you guys might. It would be easier for me to do than design and 3D print battery holders, but I can do that if I need to.

That's all I have for now. I greatly appreciate any advise and/or answers to the questions I have posted here. All info is gladly absorbed! I sincerely apologize for the MILE long post. I am excited about this project and very bored at work... Yes, at 3am. Don't ask. We Paramedics are very strange nocturnal creatures. I have been on duty for 48 hours. Going a bit nuts. :crackup:

Thanks all!!

welcome to lpf. I'm up late too, Its the off season for me.

i can answer a few questions, not all.

1. most people think safety glasses from survival lasers are good, DTR links to them on his site.

2. laser beams are basically always safe to view, it's viewing the dot up close or taking a direct hit thats dangerous. viewing a reflected beam is fine, getting the beam reflected into your eye is not. glasses are essential for doing stuff like looking at what you may be burning up close. the dot can be viewed at a safe enough distance. think of like this, onces the beam hits a surface, the light is basically spreading out all around from that point so its brightness is probably decreasing by the square of the distance or something. at a far enough distance, you can view the dot. how far depends on power of the laser, reflectivity of surface, and size of dot. let's say it's a white wall and a 3W 445nm. I'd want to be at least 15 feet away to look at the dot, and it will still be bright

3. I personally think 2.4A is a high current to drive that diode. many do it, but dont be suprised if it dies before too long. I had one go at that current after a fairly short life, and a used replacement diode blew almost immediately. I would recommend driving it at 2A or less. you wont get as much power but it should last longer and get longer duty cycles

4. your battery should work, but 2600mAh is low for two cells. I personally like removable batteries, they do wear out eventually. I'd get some higher capacity ones. 3500mAh per cell can be had

yours wont be quite all or nothing. we recently had 7W capable diodes show up on the scene

HI and welcome Zach, glad to see aa new member there are some rule and regulations here.
But you seem to be an intelligent person so read up , lots of great threads for information by using the search bar at the bottom of the screen (LPF Google bar). The way it sounds these are true to life light sabers your constructing cool.. Awesome introduction by the way very impressive and detailed. The drop down box is great for directing you to a particular topic of threads. Would like to see some of our work so don't be afraid to post some pics of your builds.

Shake basically said it all and covered your questions so i will not add a thing. It's pointless ..

One thing i must add is........
If you use lith-ion cells get some good cells. Panasonic ,AW's,sony. samsung,LG etc..
Nothing with the word ' FIRE' in it they are cheap and undependable and quite dangerous at times. You get what you pay for so get the best for these awesome builds.

Welcome again Rich

These are good, high visibility and good protection.

Eagle Pair® 190-540nm Standard Laser Safety Goggles

Thanks for the replies and kind welcomes guys! I will be sure to post build progress and pictures when the assembly stage starts. For now I am waiting on the diode and a couple other items needed.

Thanks for the safety goggle recommendations. I'll get some before I start assembly.

Good to know about viewing the beam carefully being okay.

As for batteries, I always use high discharge Panasonic or equal brand. Total snob here.

I did not realize that the recommended "absolute max" current for the NDB7875 was 1.7 amps... I just read the data sheet. It comes from DTR with the 2.4A driver set and installed so I am curious. That was an expensive diode and I REALLY do not want to burn it out. I guess if it burnt out I could justify buying another diode and throwing it into the casing. Perhaps that 6W+ module.
Anyway, putting the cart before the horse. Priority one is to try to prevent it from blowing. I'll email Jordan.

I like to burn SAFELY and the 7875 is tough and has good energy density with off the shelf lenses.

I run mine at 2.4 amps, But I buy my diodes from DTR, his are NEW and I just use a heavy heat sink and when it gets warm let it cool down. Even if they wear down a little faster I think it's worth it, but mine last...well years unless I get the diodes window dirty and crack it, it's best to pick a lens and keep it in to protect the diodes window, but they are tough and they last, just let your unit cool when it gets warm. I just go by feel, probably 120F is where I stop.

With this 2 inch by 2 inch sink I burn for 5 minutes or so, sometimes a little longer.

Hi, As for the 2.4A driver for this diode i would recommend the SXD with ramp up. I use this build method with all the NDB7875'si built. Duty times are always short with my builds, so all my builds are treated with respect , since they are not cheap.. With good heat sinking should be no problem, well hasn't been for me anyway. Other folks like to run them on the lighter side and that's cool to. Keeps the WL closer to what it should be without shifting. And stretches the life span to.

Hope it helps a little Rich

I like the old 2.4A X-Drive because they are rock solid.
The SXD has that little pot that...well it's just not what I would use with a 7875 unless I removed it and put in a resistor, I use the SXD on my NUBM44 and NUBM07E, but I have one that fluctuates 10% over the discharge of 2 high quality INR 18650's in series. Yes I know the cutoff is 6.8 volts, the SXD would probably be happier with 3 cells in series, that will be my next build that uses a SXD, a 4 C cell mag-lite with a spacer and 3 x 26650's.
The 2.4 X-drive is a proven performer, I have had many attached to 7875's and still do. They work well, I wouldn't change it.

Neat thanks!! It sounds like I may have a solid setup here. I will be gentle with it and pay attention to heat, learning on the way. The heatsink is going to be 1" in diameter, and either 1.5" or 2" long. Roughly. It will be solid and mounted right in another big chunk of aircraft aluminum, attached to a body that is all aircraft aluminum. It should be pretty good at sucking heat away from that diode.

Do you guys recommend going with copper or aluminum for the heatsink itself? I have both in a 1" bar stock.

Copper moves heat through metal faster, but aluminum seems to transfer to air faster. I would go aluminum if it's going to be exposed to the air, if its going internal and sinking to your host then maybe copper.


I also cut the back out of my module if the driver is attached to the diode and sink the 8 pin chip to the module wall.

RedCowboy said:

I like the old 2.4A X-Drive because they are rock solid.
The SXD has that little pot that...well it's just not what I would use with a 7875 unless I removed it and put in a resistor, I use the SXD on my NUBM44 and NUBM07E, but I have one that fluctuates 10% over the discharge of 2 high quality INR 18650's in series. Yes I know the cutoff is 6.8 volts, the SXD would probably be happier with 3 cells in series, that will be my next build that uses a SXD, a 4 C cell mag-lite with a spacer and 3 x 26650's.
The 2.4 X-drive is a proven performer, I have had many attached to 7875's and still do. They work well, I wouldn't change it.

Click to expand...

Hi Red,
i am hooked on modding maglights you say a 4cell 26650's now that's a thought buddy. I'll be ordering the 7+W big blue soon. i have quite a few AL sinks for the mag's all real beefy. Wow you really planted a seed in my head. Just wrote it down for reference thank you.. I like the 2 cell mags that i build Run time is forever practically.I just use the SXD on the bigger builds , but with the more powerful blue die i'll go your way with the 4 cell.

Rich)