Yellow Laser Idea (S.O.S)

I recently saw a post from a member in this forum on the combination of red+green=yellow! Loved the idea and his pics, very cool stuff.  The resulting colour one would expect would be brown (normal spectrum). But as this whole hobby has taught me, it gets strange sometimes. After viewing this gentleman’s setup, it popped into my head that DVD burners have almost an identical concept built in. The IR diode and the BIG RED essentially travel along the same route (duh..) The only thing that has to be altered is the little beam splitter in path of the diodes. I removed this, powered it up and got a nice read beam. The problem is all the loss of the red whilst passing through the unit. The beam is split in a couple of places for retrieval of various sensors and is weakened a little too much. After all it’s the red that is dimmer, and I want to conserve as much as possible. So as the project progresses, I will update and anyone who has some suggestions please feel free and drop some ideas on your way past.

The beam is split into 4 separate areas, including the main one out.

This is the way im thinking of doing it, I had to turn down the greens output. And even when I get the two lined up, focusing the resulting beam is very difficult

As you can see the dot is the shape of the aperture which it passes through. The resulting beam diverges to a huge spot within a few feet, and is a problem to focus

I am not sure that the beamsplitters from an old dvd writer will work for this due to the coatings on the glass. The coatings are most important and most likely are set for red and IR. What you need is a Dichroic mirror especially for red and green. Most Dichros of this type will allow transmission of green, but will mostly reflect red. This effectively combines both beams as if they originated from the same point source allowing a new colour beam to be produced. This is how all RGY and full colour RGB scanners work.

If you cannot get hold of a dichro , there is another way to easily produce a combined beam and will work with any colours. It's the old "mirror with the hole trick".

Take a small mirror and scratch a tiny 1.5mm hole off the reflective coating on the back of the mirror (assuming it is not a FS mirror, in which case the coating will be on the front) Take your green laser and shine it from behind the mirror at an angle through the tiny hole you have scratched (the green is usually shone from behind the mirror as it will usually have the thinnest beam) . you should now have a mirror with a green beam seemingly shining from the surface of the mirror. Now take your red and shine it at the front of the mirror at an angle at the point where the green is exiting. when you get the angle right the 2 beams will combine as if they are shining from the same point source and produce a new colour.

Hope this helps.

Here is a picture of my dichro producing a deep orange (the green was turned way down)

Jase

Nice work Tallaxo!

Thank you tallaxo for the input! Since posting, ive played around with the dvd sled and have had varied results. I will definitely try your way, as it seems like the path of least resistance :-/ Although I am still going to try to make both work. It is definitely possible with the DVD component, its just proving to be more time consuming than anything. So far ive been able to get a yellow beam, but am having a hard time combining both in a raw form and then focusing. There is one mirror in particular, it is the last one which bends the red at a 45deg. angle, the green can pass through it but reflects about 75% of the 532. This is not a bad thing because if the green is any brighter it seems to kill the balance, and the resulting dot is overwhelmed by green. I am definitely going to give the mirror with a hole a go, and do it with a FS, im trying for a burning yellow beam. With this method, will the beam split at any point? Or do they remain parallel?

The beam will always eventually split over distance, the distance depends on how well you can line the 2 up in the first place. even the tiniest fraction of a degree will eventually cause the beams to split over a large distance, but its fairly easy to keep a combined beam up to about 30 feet without proper mounts for the laser or the mirror. I made a video a while back, its on here somewhere of a combined 150mw yellow lighting some matches. I will try and find it sometime.

Jase

So id imagine it all comes down to how much effort is put in to the alignment, that’s pretty much what I figured. I’ve played around with fiber op to combine 3 780nm cd burners, and thats where the idea originally came to me. My first thought was to try with lenses, but kept getting 3 separate beams. No matter how much I diffused and spread the raw output of the diodes, the culminating lens would not provide a single output beam. Now the setup im going for is that of something compact, so im going to look for the appropriate optics that are no bigger than 10mm.

So id imagine it all comes down to how much effort is put in to the alignment

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I have combined 2 blue-rays using the optics from the  PS3 sled, I have also combined red ang green using optics from another PS3 sled. The whole lot is then combined using a cube from a rangefinder....I set it up to get a very good tight beam (although colour intensities are not yet right). When I turned it on the next day I had three coloured dots overlapping....This is due to the lasers not being warmed up I would guess so I will run the lasers longer to see if they come together again..... The above may be worth considering when you come to fine tuning.

Regards rog8811

Have you tried any combination with the blue? I just ordered a couple of ps3 sleds, and am wondering what interesting colous can be achived. ;D

wannaburn said:

Have you tried any combination with the blue? I just ordered a couple of ps3 sleds, and am wondering what interesting colous can be achived. ;D

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yep, Bluray and low power red make ......ahem Pink.


Jase.

I have all the basic combinations including White ;D .....I have attached a photo where the individual colours have been picked up by the camera, by eye it looks a good white


Regards rog8811

*edited to add photo

It gets better by the day!, cool pics guys! Man I gots some catchin up to do Hey Tallaxo, do you have any good links for reasonably priced optics, or suitable products to harvest? Namely for dichro's?