Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

Cheapest RGV laser?

Benm

0
Joined
Aug 16, 2007
Messages
7,896
Points
113
If i'm not mistaken there is a tiny lens between the diode and combining cube in the sled. I'm not sure to what diameter/divergence this focuses the laser though.
 





Joined
May 10, 2009
Messages
379
Points
28
The issue with leaving the red and br diodes uncollimated, pre cube, is that they will not have equal focal points. If you were to put a lens at the exit of the cube, the red diode would need the lens to be at a different distance than the br diode to have equal dot sizes at distance. This happens because of refraction, different wavelengths bend at different rates.

Benm: If I'm not mistaken their is a polarizing window between the diode and the cube, unfortunately I don't think it's a lens.
 
Last edited:

HIMNL9

0
Joined
May 26, 2009
Messages
5,318
Points
0
If i'm not mistaken there is a tiny lens between the diode and combining cube in the sled. I'm not sure to what diameter/divergence this focuses the laser though.

Benm: If I'm not mistaken their is a polarizing window between the diode and the cube, unfortunately I don't think it's a lens.


Not a lens, sorry ..... those are linear diffraction gratings (different lines-per-inches for different wavelenghts) ..... you can try with one of them, shine a laser beam through them and you get a line of dots in exit ..... i think they are used for "correct" and clean better the beams coming from the chips, before combine them, but i'm not 100% sure, about this .....

There's a lens in front of the reading chip, yes, it's usually a double-use element (i mean, one of the faces is a cylindrical lens, and the other is a negative concave face) ..... but they are normally molded with acrylate in strange shapes, and practically unusables .....
 

Benm

0
Joined
Aug 16, 2007
Messages
7,896
Points
113
I saw something between the diodes and the cube, so i assumed this must be a lens because the beam would be very wide without one. I looked it up and it seems to be a diffraction grating indeed (no idea of its purpose there).

If i have an intact sled i'll power up both diodes to see where the light actually goes :)
 
Joined
Sep 14, 2010
Messages
13
Points
0
If i have an intact sled i'll power up both diodes to see where the light actually goes :)

I just received my 2 first sleds today! I will play around with them and try to understand what is going on in it :)
 

Benm

0
Joined
Aug 16, 2007
Messages
7,896
Points
113
Thats a great build, but it doesnt leave the blu and red diode in their original places. As this project needs low power but minimal costs as well, that would be prefereable if it could be done one way or another.
 
Joined
Jun 24, 2010
Messages
243
Points
18
Re: Cheapest RBV laser?

Also, does anyone see any issue with having an open-loop system with 1.8° stepper motors? What are my chances to have a position out of sync with what my controller thinks? (I guess the risk gets bigger with the motor speed)


There's a simple way to close the loop. Put an opto-interruptor sensor, or even a simple microswitch with a cam that activates the switch at one point in the revolution. The controller can keep track of the number of steps and then if the signal from the home sensor comes at a different point than it expects, simply zero the counter and go from there. If it gets out of sync, it will sync itself up within one rotation.
 




Top