Tight beam on 405nm

[millirad]

Is there an easy way to create a tight beam on a blue-ray laser. Which collimator should be used that doesn't degrade power too much? Thanks

 

[chipdouglas]

You need to use goggles designed for blu-ray to be safe, and to focus. Next hit up jayrob because he has the best leses for max power.


michael

 

[Tech_Junkie]

You need to use goggles designed for blu-ray to be safe, and to focus. Next hit up jayrob because he has the best leses for max power.


michael

That does not answer his question.

I know some optics from a certain sled helps, but I dont know which one. Try the search...its out there.

 

[chipdouglas]

I assumed because he is a new member he is asking which lens, and how is the best way to focus his "blu-ray." :-? just a thought. he is asking about a collimator but then spells it "blue-ray." I assumed this person is not at the optics stage quite just yet.


michael

 

[Tech_Junkie]

I assumed because he is a new member he is asking which lens, and how is the best way to focus his "blu-ray."    :-?   just a thought. he is asking about a collimator but then spells it "blue-ray." I assumed this person is not at the optics stage quite just yet.    


michael

You know the old saying about "assume" ;D

 

[diachi]

The roithner lens 27 will do the job. Let me get a link .

EDIT: http://www.roithner-laser.com/Optics-LD.htm ( Datasheet : http://www.roithner-laser.com/All_Datasheets/Optics for Laserdiodes/LENS-27.pdf )

 

[lordoflasers]

I spell it Blue-Ray too. That's just because I'm not illiterate . The word describes a colour and it's blue not blu.

 

[chipdouglas]

well it is not "blue-ray" because the light is not "blue!" it is VIOLET. Blu-ray is the correct spelling.


michael

 

[FireMyLaser]

It's Blu-Ray, noob!

 

[FrothyChimp]

The rule of thumb in order to minimize beam diameter is to have your collimating optics as close to the emitters as possible. As such place the diode at the focal point of a positive lens will collimate the beam but using a very short focal length lens prevents the beam from diverging too large before being optically corrected. There are, however, other issues to consider. The closer you bring the optics the greater probability you could damage the diode with back reflections. As such, you must have a quality AR coating on the lens. Furthermore, most want to correct the fast axis divergence before final collimating so a cylindrical lens may be needed before the collimating lens or use a good aspheric lens with a short focal length.

Can anyone give the technical specifications of the 405nm lens I've seen discussed?

 

[millirad]

Thanks for the quick response. I think a collimator with AR glass lens coated for 405nm is what I will use. I will need to add a round brass heatsink too, as far as I know. Then I'll look for an appropriate host.

 

[LarryDFW]

FrothyChimp;

Good explanation on minimizing beam diameter.

The back focal length is a KEY parameter for keeping the beam size small.

On the best lens I am selling from a large test group, it is 2.39mm.

Here are the complete specs:

Milos did a good test on it...
and found @ 3.5% total loss compared to raw diode power, or 96.5% efficient.

LarryDFW

 

[Ammar]

I am asking because I dont know.


This is possible.
________________
-----------------------I I ---__
I I --__
Thick I LENS I --_ Focused Beam
Beam I I __ --
I I __--
-----------------------I_______________I---



But is this possible?


________________
-----------------------I I
I I______________________
Thick I LENS I Thin Beam
Beam I I_______________________
I I
-----------------------I________________I


Thanks!

 

[Xer0]

I know someone here made a Sonar with <1mm beam, but it had scatter and loss like ar coated acrylic :S

 

[dr-ebert]

@ doclazer: yes, like this (note, however, that the thinner your beam is on exit, the worse its divergence will be):

 

[suiraM]

I seem to recall that the divergence goes way up when using a beam compressor, but the drawing does illustrate the basic principle of one, though it's not corrected for aberrations. A pair of half ball lenses will do much the same thing, with higher spherical aberration, but in less space if you pick the right index.

A short focal length lens is indeed the better option, with the potential caveat that it is harder to seperately collimate the axes too close to the chip, so one might want to settle for doing so at the distance where the fast axis has diverged to match the slow axis.