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What to use to combine 650nm and 532nm?

udanis

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Hey after researching some yellow lasers and seeing the prices I stumbled upon jayrob's post ( http://laserpointerforums.com/f51/tutorial-yellow-pointer-project-cool-44427.html )of making a yellow beam by combining a 650nm and a 532nm laser.
How I wanted to do it is by having the two lasers 90 degrees from each other. Link to my idea. In jayrob's post he is using a lens out of a phr sled to combine both beams. Will this work at 90 degrees? Also I came upto this product on the o-like website RGB laser systerm combine optical lens /2pcs in a pack [OLRGML] - $29.00 : Welcome to O-Like.com, Your source for laser products but why use that when I can use a $10 phr sled. I am planning on this being a low power laser project (~5mW). If you guys can give me any hints or pointers on this sort of project let me know.

Thanks
Udanis
 





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The best thing to use would be a pass green/blue reflect red dichroic filter. That's what O-Like is selling, and it's fairly cheap for a set of two, but they could be very bad quality. It's essentially what a turning mirror in a sled is, but it's going to have quite a bit of loss. The ratio is about 4:1 for green to red for a pleasant yellow.
 

udanis

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The best thing to use would be a pass green/blue reflect red dichroic filter. That's what O-Like is selling, and it's fairly cheap for a set of two, but they could be very bad quality. It's essentially what a turning mirror in a sled is, but it's going to have quite a bit of loss. The ratio is about 4:1 for green to red for a pleasant yellow.

Is the turning mirror from the sled going to have the same loss as the dichroic filter or less?

Thanks for the help
Udanis
 
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Most likely it would have a lot more as I don't know the specifications on the O-Like dichro.
 
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small dichros make a difficult task even more so. look for something bigger and save yourself some headaches R+G= Y is easy. I saw a working combiner made from leggos and hot glue and two pointers. 4 parts red to 1 part green.
 

Benm

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The turning mirror for a PHR803 sled works pretty well. Its reflection for red at 45 degrees is very good, but you get some reflection in the wrong direction for the green that you try to pass.

I havent measured it, but eyeballing the system, it looks like over 90% of the red is reflected, and about 10 - 20 % of the green is lost (i.e. reflected 'sideways' instead of passed).
 

HIMNL9

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Just took a pair of measures .....

Green module alone, with IR filter, 155mW ..... placing the PHR dichro in the path with the right orientation (beam entering to the back side), 117mW (rotating it does not change anything, no polarization involved)

670nm module, reading 87mW directly, 1 to 2 mw passing through the dichro, rotating it (shining it on the front surface), and reading 85/86mW using the dichro for reflect the beam on the thermopile.

Reflection of red is good, and, considering that this dichro was NOT intentionally made for pass green, the fact that we found it reflecting red and BR and still pass green can be considered a luck, for hobbysts, anyway ..... ;)
 

Benm

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It is luck indeed... that optic has HR@45 coatings for 650 and 405, but hasn't been designed with green in mind at all.

The loss from 155 to 117 for the green sounds realistic to me - perhaps i underestimated it a bit, or its absorbed instead of reflected the wrong way.

If this was a dichro intended for this job it'd be a piece of shit, but considering it comes "free" as part of a 803 sled, i'd say it isn't all that bad an option for anyone wanting to experiment with red-green combination.

It might be interesting to see what the 803s 650/405 combining cube does when used with 445 nm insteam of 405. I dont have any experimental data on that yet, but i could be interesting.

Obviously a set of real RGB combining optics perform much better than parts salvage from a 803 sled.. but its expensive vs free too ;)
 

udanis

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So there are two combining components on the sled? The dichro glass and a pbs cube? Are both the cube and dichro design for 650/405?

Thanks for helping out the new guy
Udanis
 

HIMNL9

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Well, unfortunately the cube was specifically designed for combine BR (reflecting it) and left pass red AND IR, so it work good combining 2 BR, and combining a BR and a red, but NOT combining 2 reds ..... it look strange, i know, but i tried, and obtained these results ..... the internal layer of the PBS seem to be a selective dichro, other than polarized, the better combination is passing red vertical polarization and reflecting BR horizontal polarization ..... it can pass a second BR polarized vertically in place of the red, but loosing 1/3 of the power ..... and at the same time, it cannot reflect a second red in place of the original BR, no matter the polarization (well, being sincere there is a small part that become reflected, but you lost 85% of the power to the sanded face, also in the better orientation, so it's unhelpful, for me)

Still good for red-BR mixing, anyway ;) ..... not yet tried with 445nm in place of the BR, anyway, i need the time for take together a setup (*signed it for a future test* :p)
 




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