One of the biggest problems when using a laser collimator is making sure the secondary mirror is in the correct position.
I've come up with a very simple method of ensuring the secondary mirror is centred in both the focuser and aligned with the main mirror....
A piece of card cut to a rectangle the width the same as the secondary and the length the same as the face length of the seconadry ie it fully covers the secondary mirror. Mark the centre ( use the diagonals) and punch or cut a small hole ( about 4mm diameter)
Gently stick it over the secondary using masking tape tabs at the edge ( watch you don't touch the secondary reflecting surface). This will give you a 4mm central aperture on the secondary mirror.
Insert the laser and align the secondary such that the laser spot sits inside the 4mm hole.
Look at the reflected spot on the main mirror, re-align the secondary until this spot is central to the main mirror.
At this stage the reflected laser spot should be directed back to the secondary by adjusting the main mirror, the spot should once again be in/ on the 4mm hole. When this is achieved, the final reflection from the secondary should illuminate the circular scale in the laser itself.
The secondary mask can then be removed....
You should find this gives you very good collimation and you can be assured the secondary is correctly positioned relative to the focuser and the main mirror optical axis.
Give it a go, and give me some feedback on this "Magic Merlin Mask"..............
