New Laser gun 75W+

[Borislav@87]

I am wondering if there is a single lens that has a long focal length of 1 meter or more?

 

[RedCowboy]

Yes these is, here's one that's

I am wondering if there is a single lens that has a long focal length of 1 meter or more?

Yes, here's one that's 1 meter ( 1000 mm ) and I have tested these, they help some for the 2 meter range, but what really works is a big homemade beam expander, a double concave then a sliding convex or double convex.

BiConvex Optical Glass Lens 50mm Dia 1000mm focal length NUBM31T3435363837 Array | eBay

<p dir="ltr" style="margin-top:0; margin-bottom:0;">Ground Glass Lens - Double Convex 50mm Dia. 1000mm focal Length For NUBM31T, NUBM34, NUBM35, NUBM36, NUBM37, NUBM38 Array </p> <br> <p dir="ltr" style="margin-top:0; margin-bottom:0;">Concentrate your array to a single spot at a one meter...

www.ebay.com

Here's some testing I did a while back, results were good at the 5 meter target.

 

[Borislav@87]

@RedCowboy

Thanks. I need a single lens because I want it to be compact and easy to carry.
I have ordered several lenses from Aliexpress. I might try to assemble a lens.

30mm 40mm 50mm Glass Double Convex Concave Glass Lens Focal Length 50mm 75mm 100mm 150 mm 300mm Optics DIY Projector

https://a.aliexpress.com/_mLN3PKu

 

[Borislav@87]

@RedCowboy
I found on Aliexpress a double lens with a focal length of 1250mm. I will write when I get it. Its price is very good right now.

21 22 46 52 mm double cemented Achromatic Convex Objective Lens DIY Professional Refractor Astronomy Telescope Accessories

https://a.aliexpress.com/_mNdrVL2

 

[RedCowboy]

To make a beam expander I like to use a concave then a convex to zoom to focus.

 

[Borislav@87]

Yes, I got that. I also ordered a double concave lens and a convex one. I ordered from several places different lenses. When they come I will experiment. I'll actually be able to do something similar with your adjustable lens laser that's in the box. Simply, the box will be placed on a board on which there will be two lenses with the possibility of adjusting their distance. And for the one on the drill I only need one lens and the one I ordered if it can really focus at about 1250mm it will do a perfect job for me.
It's actually the double convex one I ordered

50mm FL 100mm
Optical Glass Double Concave Optics Biconcave Focal Length -40 -50 -100 -123 MM Eyepiece Minifier Lens

https://a.aliexpress.com/_mOSUPmg

 

[RedCowboy]

Watch out for cheap optics, they can be full of bubbles/trash.

 

[Borislav@87]

@RedCowboy
I don't know why, but it always bothers me when I put optics in front of the array, because the optics without a coating to return the light back, make a reflection and the focus is right in the array itself. I did a test the other day with a biconvex lens that I placed in front of the array at close range and shifted the angle slightly. The reflection from the beams tried to burn the laser box. Actually when I got the NUBM35 front array all 14 diodes were working. After some burn-in testing, I had put in this very lens that brings back the reflection and one of the diodes died then. I don't know if it was a coincidence or if the lens damaged it, but it happened right when I had put that lens on the front

 

[RedCowboy]

Uncoated optics only lose something like 5% and the back reflection is fairly diffuse, any energy reaching the facet would be tiny.

You could source AR coated optics or find some quality optics you like after testing them and have them coated, but for these crude arrays it's hardly worth it.

A better way would be to build our own arrays and align them properly.

10 NUBM0F modules with G8 lenses knife edged to overlap at infinity or max useful distance, would do a lot better.

You don't even need a PBS cube like in this pic, beacuse of the way the fast axis outruns the slow, just knife edge 10 beams to all pile on top of each other at max working distance.

You could use a couple of these to build a neat burning array and the reflectors are AR coated.

Micro Knife Edging / Beam Combiner Module

for an uncomplicated combining of up to four laser diodes

www.lasertack.com

 

[Unown (WILD)]

Cool pistol

I knew this was gonna happen ... sigh. Okay why are you copying another members nickname?

 

[Borislav@87]

Today I added these strips for wardrobe and cabinet corners. I'm going to put two phone magnets on top of them that I used for the front one, and that's how I'll put the lens on and off. I put a little glue on each one because the screws don't grip very well in the aluminum fins of the radiator

 

[Borislav@87]

Burning