Laser collimation.

[Daz Type-R]

How do you collimate a laser collimator?

[Bizibilder]

Put it in something like a "V" block (you can make your own!) and turn it on to show the laser as a dot on a wall around 20-30 feet (10m) away. Rotate the whole laser collimator in the "V" block and the laser spot should stay in exactly the same place. If not - the there should be three screws (often hidden below some "filler") around the body of the laser. Remove the filler and VERY gently adjust the screws until the laser spot no longer moves when the whole thing is rotated. Whatever you do dont damage the laser by tightening the three screws too much.

Hope this helps.

[Daz Type-R]

Brill, thanks.

[JamesM]

Sorry I have to disagree with the V block method. The reason is because it introduces two axis from which to reference any error, where in fact the collimator only normally uses one point of contact within the scope's focuser. In order to replicate this method of use accurately when collimating the laser itself, will require you to cut an accurate hole in a piece of MDF which is supported vertically and that this newly cut hole matches the external circumference of the collimator. The idea is to be able to insert the collimator into this hole and to project the laser beam over a distance of say twenty feet and to adjust the three grub screws until the beam holds a fixed position when the colllimator is turned 360 degrees. The reason for the distance is obtain the maximum possible accuracy for using to collimate anything that is shorter.

For those who have a Hotech collimator (which uses an expansion method to secure itself centrally within a given aperture) the above described system won't work because the nature of its securing method will prohibit any turning within the hole that was cut into the MDF. As an alternative you use an existing 1.25" section of a diagonal to first help fasten the Hotech and it is the external diameter of this 1.25" attachment that determines the size of the aperture that is cut in the MDF. This will then help facilitate turning the Hotech (via the smooth outer surface of the diagonal part) through the required 360 degrees to achieve best collimation.

James

[Jason D]

You can use your focuser instead of a V-block. Just decollimate your primary mirror until the laser beam misses the secondary then you can adjust the laser collimator until its beam remains "stationary" against a distant wall when rotated in the focuser.

Optionally, you can lay down the OTA on a table horizontally and have the focuser vertical to avoid dealing with slop.

Jason

[Space Cowboy]

That's a great idea Jason I will try that. The v-block method is far too wobbly.

[Space Cowboy]

Wouldn't rotating the laser in focuser whilst looking at the beam on the primary work just as well?

[Lorne]

Ive noticed that when I rotate my laser collimator in the focuser the beam wanders quite a bit, I assumed it was a bit of "play" in the focus tube. I never thought for a minute the beam itself may not be collimated.

[pook]

Wouldn't rotating the laser in focuser whilst looking at the beam on the primary work just as well?

I suppose Jason recommends this because the extra distance will greatly magnify smaller errors, and hence this way of more accurate.

[Jason D]

I suppose Jason recommends this because the extra distance will greatly magnify smaller errors, and hence this way of more accurate.

Yes, this is the reason I had in mind.

Jason

[Si W]

You can use your focuser instead of a V-block. Just decollimate your primary mirror until the laser beam misses the secondary then you can adjust the laser collimator until its beam remains "stationary" against a distant wall when rotated in the focuser.

Optionally, you can lay down the OTA on a table horizontally and have the focuser vertical to avoid dealing with slop.

Jason

Yes, i use this method as well, it's simple aud full proof .