A 10 x 10 line square grid pattern. It spreads 21 degrees which allows centering of optics as fast as f/ 2.7. This pattern is recommended for general use because it can be used with the fastest telescopes likely to be encountered.
When it comes to lasers and collimation, one of the most trusted names in the business is guru Howie Glatter. His uncompromising quality and dedication to above average products, not only put his name above the rest - but in demand as the finest available on today's market. Usually a manufacturer doesn't take the time to explain to a customer exactly why their product excels over others - or why it performs better - but not Howie. Here's what he has to say about his new Howie Glatter Holographic Laser Collimator Attachment:
The holographic collimator has a removable diffractive optical element ("hologram") placed in the beam, just ahead of the laser. It diffracts light from the laser to project a diverging, symmetrical pattern around the central beam which is quite useful for centering optical elements. My standard pattern is an illuminated ten line by ten line grid, forming a large square box enclosing eighty-one smaller squares. It covers a wider angle (21 degrees) than any other holographic collimator, which allows direct centering of f/ 2.7 to f/ 35 optics. It may seem counter-intuitive, but the square grid pattern gives greater sensitivity for centering circular optics of arbitrary size. If a mirror or lens is decentered by only a small amount against the grid pattern, it produces a proportionately larger asymmetry in the intersection points of the grid lines with the perimeter of the optic. Cross-hair patterns do not have this property.