A line, not a dot from a Laser collimator?

[[1ponders]]

I was recently given a GSO Laser Collimator to donate to the Mapleton School Observatory (Thanks ;) ) . It was un-used and still in the box. When I first turned it on it was fine. But this morning I went to use it, and after changing batteries I have a line and not a dot as a laser beam???? Is was fine when I first turned it on this morning.

has anyone come across this before?

[Steffen]

Most cheap (sub-$100) laser collimators I've seen are like this. This includes a GSO one I bought a while ago. They seem to lack a proper circular mask. The laser diode itself yields a rectangular shaped beam.

Maybe the cheapies do have a mask but it's not properly cut or easily dislodged. Compared to my Glatter collimator (which has a detachable mask) the elongated beam shape of the GSO isn't even sharply defined but fuzzy.

IIRC, there has been a thread on IIS recently about fitting a DIY mask to GSO and similar collimators.

Cheers
Steffen.

[bmitchell82]

A tactfully placed piece of aluminium foil does the trick paul :) pull that thing apart and make it right again!

[[1ponders]]

Thanks for the thoughts. On closer inspection (with glasses on) what i took to be a line looks more like 3 slightly overlapping spots.

You'll have to explain Brenden. I've never used a laser collimator before ... though I've seen one used. :)

[RB]

Paul, a simple solution is to order a nice size SDM that's been well collimated so you can adjust the laser back to centre.

:P

[jjjnettie]

:eyepop: Don't go giving him ideas Andrew. :rolleyes:

[[1ponders]]

:confuse3:

[jjjnettie]

I wouldn't work Paul, you need level ground to put it on.

[[1ponders]]

I can do that :D

[renormalised]

Jeanette, don't go giving him ideas!!!:):P

Silly, because I just thought of one....Paul, find a ridge on your property that points exactly in the direction of the SCP. Flatten part of it and permanently mount the suggested SDM on it in the same orientation. One el cheapo EQ mount!!!!:):):):P

[bmitchell82]

Unscrew the back where you would put the batterys in.
unscrew the 3 grub screws that are for collimation (don't worry it wont be collimated anyhow)
remove the small pen style laser
unscrew the end cap (aperature cut)
place a piece of foil on that
replace the end cap
with a pin fine tipped biro, paperclip pierce a hole in the foil, Test to see if you get a nice round bright spot.
If so, then replace the laser in the holder.
retighten and make sure you can get the laser to come out housing
then put the laser in a V block (make it or just sit in something so you can roll it round and round) make sure it wont move.
get it to shine on a wall about 5-10 meters away, stick a piece of paper to the wall.
(easier if you have 2 people for the job)
mark 3 lines on the paper (120 deg apart). Roll the laser to the first one. Mark a dot, repeat for all 3, then start adjusting using the 120 deg lines to get your laser closer to the center point. if your crafty, you can rotate the paper to co incide with your 3 grub screws to make knowing which one to adjust easier! just remember it is a Iterative adjustment move to each line and bring it closer to the center. try to get as close as you can 5mm circle at 10 meters means a very small amount of error when talking about a FL of 1200mm

There you go one fully collimated laser.

-Note, don't go hard on the grub screws as it will dent the housing of the laser, :) use the its just tight enough, loosen another system!

HAZZAR :thumbsup:

[erick]

And if you are pulling it apart, you might as well do this mod.

[[1ponders]]

Damn this is a great site. :lol: Thanks guys. :thumbsup:

[bmitchell82]

hehehe eric, thats exactly what i explained :D the text version!
:D go forth and pull apart.

[[1ponders]]

I will Brendan. :)

[erick]

Taking out the second o-ring makes sense. I should have one tomorrow to play with.

[RobF]

Sorry - what do you gain by removing the 2nd o-ring Eric?

[Steffen]

In fact, the one you're receiving has had that mod already taken care of :) I put the rear ring up the front where the other ring is (you can remove it altogether if you like, I just didn't want to lose it). Collimation is far more predictable and easier this way.

Cheers
Steffen.

[Steffen]

If you have a barrel suspended by two o-rings on either end and three collimation screws about two thirds along the barrel between them then adjusting the screws can give interesting results. If you tighten one you'll shift the end of the barrel closer to the screw - until the ring on that end won't compress any further, then you start shifting the other end, counter-acting your adjustment.

Ideally, a barrel should be fixed (in position, not angle) at one end and held by collimation screws at the other. That's what this mini-mod is about.

Cheers
Steffen.

[RobF]

Cheers Steffen
Got it figured now :thumbsup:

[erick]

Mate, just arrived and it's in beautiful condition! Many thanks! I see the rear O-ring has been moved. The spot is a good shape and size. Nothing I can play with :sadeyes:. Except, maybe, wrap a bit of contact around the 1.25" barrel! :D But with my Antares twist lock adapters, I don't even need to do that any more! :thumbsup: OK, I'll put it into my super-duper collimating jig and check self-collimation!