Improving Red (Maybe ALL) Beams

[badger1666]

Thanks eric another great informative video by yourself

[badger1666]

a question eric, so which part of your lens setup gave you the reduction in divergence ??
the way you setup the cylinder lens or the pcx lens ?
thanks

[planters]

Conventional PCX with both flats tword the central focus remained unchanged. It was the flipping of the cylinders that improved the divergence. This makes sense as the beam is diverging in only one axis as it is passing through the thick windows.

[f150trk21]

Hey Eric
I want to incorporate your spatial filtering technique with my dual 73s, is there any reason not to use a shorter focal length then 75mm, like 50mm or even shorter?

thanks

[LaNeK779]

no specific reason.
maybe longer FL lenses are a bit easier to setup and a bit more forgiving though

[planters]

Correct. 50mm would probably be only moderately harder to align and the positioning of the filter blades will have to be more precise. As the FL gets even shorter the alignment would be too dificult;, in my opinion.

[tribble]

I love this video. I keep watching it over and over; there is so much good stuff to soak up from it. Thanks for sharing, planters!

I need to find one of my old physics texts and re-read the optics section. Not sure what it means to have a -25mm and a 100mm cylinder lens pair spaced 15mm apart. (is it 15 or 150? Looks longer than 15 due to bounce mirror?)

[planters]

If the beam started out parallel and you wanted a Galilean telescope to enlarge,but re-collimate the beam then the spacing would be closer to 75mm allowing for the finite thickness of the lenses. So, in reality you would start at 75mm and make a slight (few mm) adjustment. But the beam out of the red collimator is already diverging pretty rapidly even though it is optimally focused and this adds to the divergence of the negative lens. This is why the 15mm or so spacing. This is determined empirically anyway.

[resunltd]

Hello all,
I am new to the forum, a long time laser enthusiast from Manchester, NH. I've been using lasers in various projects since the late 70's and over the last two years built a couple of "exploratory" projectors. A 1W 532 DPSS and a 2W RGB. After looking at all the inspiration on this forum I decided to try a full diode build. I have an issue that requires the advise of the collective.

I am using Laserwave LWRL 638, LWGL 520, and LWBL 462, at 2W each module. the combined beam is directed into 506's / with the larger mirrors. Controlled via a QS-3. All is functional.

My issue is the near field beam size and shape of the red laser. The laser is an array of six or eight diodes. I have not opened it up 'cause it's new and under warranty. The profile looks like two distinct rectangles side by side with a black band in the middle. Is this normal? There is no way that the beam fits on the mirror.

I have tried planters excellent spatial filter with dual 75mm lenses. This does not have the dramatic effect it did in the video. Is there any way to get the near field tighter?

Thanks for any ideas.

[planters]

The spatial filter is the LAST stage in improving a laser beam. It is difficult to begin with a "black box" because you can't open it due to warranty and so you can't evaluate the lay out. If the red is performing according to the manufacturer's specifications then you're kinda stuck, but a 2W red that doesn't fit the 5mm aperture 506 mirrors is pretty awful if it is indeed performing to specifications. Check the specifications then measure the beam dimensions in X and Y near the module and at say 10 meters away. Do this with as few intervening optics as possible. The rectangles and the separate beams is the inevitable result of trying to nest multiple beams side by side. The better you do the smaller the dark space.

If the near field is substantially larger than 5mm square, as in "no way fits on the mirror" then as I said that's awful. However, if you're willing to go down the rabbit hole then YOU can build an uncooled, dual P73 diode module, combining with a PBS cube and also beam corrected...and then spatially filtered and this will definitely fit those mirrors and easily exceed 2W.