Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, Philip Pemberton <ygroups@...> wrote:
>
> On 04/03/11 18:40, jmelson2 wrote:
> >> What kind of resolution can you obtain with your plotter?  What dot size do
> >> you get with the 670nm laser and 13mm FL lens?
> > The machine runs at 1000 x 1000 DPI.  I defocus slightly so the raster lines blend in to a solid black.
> 
> Is there any chance of you posting some more info about the optics block?
>
I'm not an optics guy, I just fooled around with it until it worked.
First, I got a 670 nm 5mW laser diode, but it sprays the light in a big elliptical pattern.  So, I put a 3mm sphere lens in front of it, almost touching the glass window on the front of the laser.  I just glued the lens into a hole in a plate.  I have it set up so I can slide the laser around so the more collimated beam from the sphere lens is pointing straight ahead.

I then put a piece of aluminum foil with a large pinhole in it slightly in front of the sphere lens.  I blacked the foil facing toward the film with marker pen to kill reflections.

I have a 13mm microfiche objective lens about 6" in front of the laser, and about 1/4" from the film.  The whole assembly can be slid in and out for focus adjustment.  This made the spot too large, so I put a double-meniscus lens in the middle of the tube.  I don't have any specs on this lens, it is out of something I scrapped.  I would guess this lens reduced the spot size about 2 or 3:1.

Jon