The Shop > Tools
Anybody build Dan Gelbart angled laser centre finder?
Arbalist:
Good to know Pekka. :thumbup:
I have ordered what is described as a 1mw Laser from Hong Kong. The primary reason for ordering another is that it is smaller than the one I have at present so if suitable it will be easier to mount. Should arrive in a week or two.
PekkaNF:
I ordered three "smaller" lasers as well, will take some time to get them. Those are small, but not "focusable", hope they are weaker. I have intention to check which parts I need for collimation, but I got sidetracked with ND filters and polarization if I need to live with this one. Some math involved to collimation lens calculation and some input values are required that not all are available....I will resort to normal lens calculator and approximate, questimate and testimate it.
Which laser you bough? I'm hating the idea of getting too exited and buying too much junk. "Just in case". But this is pretty cheap way to learn more.
Pekka
Arbalist:
This one Pekka.
http://www.ebay.co.uk/itm/381148296821?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
PekkaNF:
Got one cross-line 5mW laser from mail.
I got some time to play with this cross-line laser.
1) I took the cap/grid lence off and noticed that there is a lense (group?) on threaded holer, that allows "focus" adjustment.
2) Original dot is not extremely clean, about the same than "focusable laser module" that has been linked here.
3) Tried prism to angle the beam and it worked out pretty well. I was expecting some artefact here, but quick look seems to confirm that with a little adjustment laser and prism will compensate oavality of the beam.
Laser inside a grey plastic cable gland
prism from a binoculars (roof prism type, pechan prism used)
ND filter, thanks Vic
Black cardboard.
It looks like it is possible to use prism, but to adjust the beam only with the prism is not optimal. Surface mirror?
Pekka
PekkaNF:
Little testin with pinhole.
1) I made a pinhole onto black craft cardboard, smallest pin I had.
2) I placed the pinhole on front of the collimation lense and it produced interference rings as theoriy says, clearly visble when focused on about 200 mm and then viewed at three meters trough frosted glass.
3) Dot density is greatly reduced and dot is pleasingly round, but not exceedingly small at 200 mm, due to interference no doubt. However when projected onto machined metal surface it looks very promising.
My gut feel about this (not very sientifically based) is:
Pinhole can be used to clip the size of the dot, but to be highly effective it needs to be placed carefully, probably near focal point and in this system it means some extra lenses.
Pinhole naturally cuts some intensity, specially when placed into "wrong place" wether this is good or bad depends on situation.
ND filters I got do no seem to reduce quality of the beam.
Pekka
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