Re: Fs: NEW HOSTS ADDED TODAY 5/9/15 NEW CARBON FIBER WRAPPED HANDLE
I have a expander design I just sent him which uses a single PCX lens which when coupled with a defocused Aixiz module lens inside a host works well. The unit threads on to the end of the host, this way the host can be used with or without it, if he makes an end cap too. The way this one lens expander works is by de-focusing the output of a aixiz module lens which can be used to adjust the spot diameter of the beam to match the diameter of the output PCX lens which will collimate it the rest of the way to an infinity focus. In truth, this method isn't really a one lens beam expander because when adjusting the focus of the lens in the Aixiz module this way, it mimics the function of a concave expander lens found on the input of a normal beam expander by varying the amount of expansion (when it is out of focus) to make a wider spot. Through this method your G2, three element lens or what have you, in effect becomes a variable expander lens when used that way. The collimation of the beam back to infinity focus is accomplished by sliding the tube with the large PCX lens in or out with a set screw to lock the focus when done, see the attached drawing as a .jpeg.
If you aren't interested in having a threaded coupling, he could probably make something which just fastens down over the end of the pointer to fit the host that way without threads. I asked for a lens tube with a 2 inch range of adjustment to allow a wider choice of focal length for the lenses I can find on ebay. I want to use a 2 inch 50.8mm/2 inche diameter PCX lens in mine which is rather large for a beam expander so you might want just a one inch ~25mm diameter lens instead. I want such a large lens to reduce the divergence to a lower amount than a more common 25mm beam expander can produce, but that makes a very fat beam which is probably best suited to the higher power laser diodes so you can see the beam better from the side. If you just want to correct the rather wide divergence of a multimode laser diode, a much smaller beam expander lens could be used to adjust the divergence down to be comparable to a 532nm DPSS laser, for that maybe a 12mm ~1/2 inch diameter lens would suit you better.
I have another idea to add the ability to focus the Aixiz lens from the outside, when the expander head is attached, but it isn't shown in the drawing. Through such an arrangement, having both lenses adjustable you would then have a variable beam expander, adjust the Aixiz lens to make the spot which falls in the PCX or output lens smaller and you have less expansion, larger to match the full diameter of the output lens more expansion. Best of both worlds, a thick or thin beam. Of course, when the beam is adjusted to be thin the divergence is then close to where you started, perhaps slightly less but with increased loss from having another lens. For this arrangement I recommend having an AR coated lens to reduce the loss from the reflection produced from the back side of the PCX output lens.
- my bad
