To most accurately test and collimate telescopes, reflectors, catadioptric, and refractors, you must perform a star test. However, to do so, you need a star.
Sadly, a real star is not always available due to poor weather conditions or location.
Even when a star is available, you will need a good tracking system for doing star test as the star is always moving.
Also air turbulence may affect your test, and the real star may not even reveal the true quality of your telescopes or give you a perfect collimation.
However, an artificial star is an excellent alternative to do the star test. With an artificial star, star tests can be accurately conducted anytime and anywhere.
However, the problem with the artificial star is that you need many different sizes of artificial stars for different telescopes of different apertures with different focal ratios, and even for the same telescopes but at different distances, and under different lighting environments.
The Binocular and Telescope Shop
With the Hubble 5 Star Artificial Star you can collimate your telescope no matter what aperture or focal ratio.
Bright LED light shines throuh 5 precision pinholes (50/100/150/200/250 microns).
Comes with Magnetic Mask to block out pinholes not being used.
Star Test indoors.