Collimation via barlowed laser

[moriniboy]

I recently found an interesting Sky and Telescope article for using a barlowed laser to collimate newtonians, this was the photograph used in the article.

The only problem is that in reality the projection screen is that high up the draw tube its only visible using a compact mirror (photo is of our society's Skywatcher 200p dob)

I had already fabricated a screen for the bottom of the barlow but decided to abandon this on favour of an alternative.

My final solution was to make a card screen which slips over the end of the focuser tube

 

Initial impressions are that it works well.

 

 

[Ricochet]

Your laser has a 45° face so you do not need a screen at the bottom of the tube. All you need to do is turn the laser so that you can see the face while at the primary end of the telescope. 

[moriniboy]

Agreed, but not accurate enough using the in built screen

[spillage]

I always thought that this would just project the doughnut sticker onto the face of the collimator.

[Ally8446]

1 hour ago, spillage said:

I always thought that this would just project the doughnut sticker onto the face of the collimator.

That's exactly what happens @spillage. I've always found it to be highly accurate.

Al

[moriniboy]

Here is the original article

collimation_with_a_Barlowed_Laser-1.pdf