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FrozenGate by Avery

Focal distance adjustments, focal collimation?

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xanatos

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Joined
Nov 24, 2007
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OK, Now that I've cooked small pieces of nearly everything in sight with my GB red diode, I'm wondering if anyone has yet designed a method to:

1. Easily and rapidly adjust focal distance - obviously there are times when you want your beam pinpoint focus close, and others when you want it several feet out. Currently, that can only be accomplished by manually twisting the Aixiz module lens assembly.

2. Focus the beam and collimate it at the focused diameter - so it's hot from the lens out several feet. I would guess this would take a small second lens- probably a good glass one - concave...??? Optical gurus out there?

For my item #1, I'm wondering about a very small motor - I got some out of a Sony Mavica digital camera that even had a gear reducing head mounted to the motor... but I'd probably need a stepper to control the turns... also a small washer between the lens assembly and internal spring to eliminate the spring catching on the plastic when turning opposite the spring's cut end.

Item #2 is where I have no clue...

Thanks for any ideas/suggestions.

Dave
 





what do you use to focus now? i figured thats what everyone wanted an adjustable aixiz module for.. you can always try using some microscope/telescope optics. ive seen pen sized adjustable telescopes (pirate style). if those would work i guess binoculars would work just as well. if you got access to any of those things try it out and share the results. pics/movies are always nice to see. even if you dont get the results you want. still be neat to see a 50 foot dot on a mountain or the moon or something
 
Actually it's just twisting th eblack plastic "optics head" in the Aixiz module that I'm doing now to adjust, but, being the technogeek I am, I want to be able to focus nearly instantly, without clumsily reaching around and sticking my fingers in front to tweak in a focal distance.

Last night I started thinking about NOT using the Aixiz module, mounting the diode into a good heatsink, and having the collimator lens on a small rail-mount that slides in & out in front of the diode, with a stepper or multi-stop solenoid controlling the positioning. This way I could use a control of some sort to set the focal length I want at any given instant.

I was also thinking about how auto-focus works on cameras - a very similar arrangement. It might be even nicer to have the laser automatically focus on whatever surface I was aiming at - possibly even using a small 5mW laser as the aiming device that is also the focal director, and the main diode then operates on demand... all sorts of possibilities, and the parts are available so I believe I can do this in a very small hand-held package.

Anyone good with optics and/or understand autofocus principles that do NOT involve CCD or other matrix sensors?

Thanks!
 
Thanks - that's helpful. That's a nice device you've got there! Love the beam shot too - what power is that running at? My GB diode is drawing 280mA and cuts paper, lights wood without a match head! - but the beam isn't very visible unless there's smoke/fog in the atmosphere. You must be running a hotter diode in there than I.... what be it? :)

Dave
 
It is senkats GB red, run from an lm317 and 5ohm resistor....I did measure the ma when I built it but cannot remember what it was :( I think when I took the photo the room was a bit dark so the camera did a long exposure....

Regards rog8811
 
I wonder if you could use that lens and stepper motor that comes with the Blu Ray lens assembly since the lens is already mounted and ready to go.
 
Blu-ray lens assembly - sounds worthy of checking - thanks!

I did a little design session today and came up with the beginnings of a useful design using a regular micro-motor from a digital camera I parted out. Using an idea similar to rog's of securing the focal ring of the Aixiz module to a larger ring, but the ring will be a small gear. I will drill and insert a very small rare-earth magnet into the body of the gear, and use a hall-effect sensor to sense rotations. This in turn provides pulses to a 74LS90 binary counter and the A B & C outputs are being watched by 74LS08 AND gates (connected to form a 3-input AND gate). When the count reaches 111 (7 rotations in one direction) it inhibits the motor drive. This sets a working range of 7 turns max. The direction switch thrown manually resets the 7490 to 0000, and allows the motor to go the other way until a count of 111 has been reached again, resulting in motor stop again. A TIL111 display allows the count to be monitored, and I will get used to knowing, pretty quickly I imagine, where the focal distance will be at a given number count (from 0 to 7). I will set it so that 0 will be around 2 to 3 inches from the emitter, and I'll see where 7 puts it. If it turns out that 7 turns is too much, I'll make 2 - or even 3 - magnets into the gear, which will divide the turns count by 2 or 3.

The motor has a reducer assembly on it and turns the output at about 2 revolutions per second on a 1/8" diameter gear, which will in turn be driving the focus ring gear at about a diameter of 1", so it should turn slowly, but fast enough for any application I will have.... Until I get a diode that does 60+ watts and I can make a working laser rifle! :) Bwahahahaha!!! ;D ;D ;D ;D

I have a few parts going onto the protoboard now and the motor and reversing circuit are working. The toughest part of this is probably going to be sourcing gears and identical replacement motors/reducing boxes so I don't have to dread the day one of the "one-of-a-kind" parts craps out.

Anybody with good micro-gear sources? :)

Thanks!
 
Nice! I've been tearing apart old dead cameras and finding a wealth of tiny motors and gears. My only concern is wear on the threads of the Aixiz module focus module. Wondering what kind of plastic it is - concerned about using lubricants as they may capillary their way to the lens itself - or worse - the diode - as the unit heats up form use. If the threads wear - the unit obviously craps out.... issues..... :)

Dave
 
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