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Registered Member #95
Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308
I bought a PHR-803T sled assembly on ebay recently to make a violet laser pen. I run it with a constant current source of my own design, set at about 80mA, as there's no point in burning out a fancy colored laser. I tried collimating it with a cheap laser pointer assembly, but the beam divergence was large. I saw on the laserpointerforums that the final focus lens from the PHR-803T sled is sometimes used to get a smaller beam. c4r0 has made his own collimators, so I thought I would give it a shot.
The beam turned out good enough for indoor use, but it's still diffuse. What appear to be rings are evident in the laser reflection. The point of the laser looks to be on the edge of the second most outer ring, so I guess the lens is a bit off center. Other than that, can I expect the lens to collimate the beam as good as, say an Aixiz module if I get it adjusted right? I want a long range beam from the pointer, burning stuff isn't important with this laser.
Registered Member #151
Joined: Sun Feb 12 2006, 02:53PM
Location: Poland
Posts: 153
Hi! I was using something very similar to aixiz modules to collimate 405nm light and it works fine - . Your problem may be that the lens is not in axis with the diode just as you noticed. Also the lens could get dirty from glue vapours - I've had problems with it when making my collimators. And the third reason may be the lens itself. It's some odd kind of Fresnel lens so it may not be perfect to collimating the light in the way you want. I would suggest using aixiz module housing, it's cheap and reliable. Notice that in the 405nm range Rayleigh scattering is much stronger than with red light - you will never acheive a sharp little spot in distance of several meters with 405nm light.
Registered Member #99
Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637
c4r0 wrote ...
Hi! I was using something very similar to aixiz modules to collimate 405nm light and it works fine - . Your problem may be that the lens is not in axis with the diode just as you noticed. Also the lens could get dirty from glue vapours - I've had problems with it when making my collimators. And the third reason may be the lens itself. It's some odd kind of Fresnel lens so it may not be perfect to collimating the light in the way you want. I would suggest using aixiz module housing, it's cheap and reliable. Notice that in the 405nm range Rayleigh scattering is much stronger than with red light - you will never acheive a sharp little spot in distance of several meters with 405nm light.
Nice work! What kind of driver is that that I see in the pictures? Looks like some kinda inverter? Matt
Registered Member #151
Joined: Sun Feb 12 2006, 02:53PM
Location: Poland
Posts: 153
mattrg2 wrote ...
Nice work! What kind of driver is that that I see in the pictures? Looks like some kinda inverter? Matt
Thanks! Yes, it's a current source made of a voltage regulator (BD9703, a buck converter) desoldered from a DVD writer PCB. It's the third circuit described here:
Registered Member #95
Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308
101111 wrote ...
uzz0rs, I am very curious what type of driver circuit you are using..
It's a simple little linear regulator, made of discrete parts. Unfortunately the minimum voltage is 3V, so only 9V batteries can be used for practical purposes. An inverter design like Karol has, accepting a single AA battery would be neat.
Karol, can you take a picture of your beam shone at something distant? I'd like to see how far the beam can reach despite Rayleigh scattering. Currently mine hardly reaches across the street.
Registered Member #151
Joined: Sun Feb 12 2006, 02:53PM
Location: Poland
Posts: 153
No problem
Both the laser and the camera in about 10cm distance:
Laser about 5m from wall, camera close to wall
Both the laser and the camera in about 5m distance from wall:
On the last pic the spot looks just like on the middle pic. Actually, when looking with naked eye the spot in the third situation (both laser and me in 5m distance from the wall) has a strange halo that looks to be about 5cm in diameter. When I'm looking at the spot I can't focus my eyes on it, the same feeling when you wear somebody's glasses. I have no idea why the camera can't see this phenomenon, I was sure that it's Rayleigh scattering but now I'm confused
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
The reason you can't focus on the spot at long distances is quite simple that--you eye can't focus on 405nm light (it is for all intensive purposes UV). There really isn't anything you can do about it, human eyes just don't work at that wavelength.
Also, the lens out of the sled really isn't well suited for collimation, it is an ashpere designed for focusing onto a cd and has some pretty weird specializations to make it work well for that. A much better bet would be the lens out of a cheep laser pointer, however you might need to modify the module to allow the lens to be closer to the laser diode (the lens will have a shorter focal length at 405nm than at the 650 it was designed for).
Registered Member #1811
Joined: Sat Nov 15 2008, 11:52AM
Location:
Posts: 14
A question on my behalf guys, i asked around computer shops for a malfunctioned DVD and got one. The diode was red and i burned it out by accident. Would a cheap laser pointer lens work for a collimator for this? Im planning to make a screw assembly out of brass to get the lens closer or further from the laser beam. I will post pics in a new thread if i achive this. And also any other ideas of which lenses i can use with this laser is appreciated.
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Blu-Ray Laser from PHR-803T sled
Yes, it's a current source made of a voltage regulator (BD9703, a buck converter) desoldered from a DVD writer PCB. It's the third circuit described here: 
