Optional holographic accessories screw into the opening of the laser and have a white display front surface. They contain an optical element that diffracts most of the laser light in a divergent symmetrical pattern around the central beam. The projected pattern is useful for centering optics by making it symmetric with the edge of the optics.
There are three different patterns available:
A 10 x 10 line square grid pattern is supplied as standard unless otherwise requested as it is the widest pattern. It extends 21 degrees, allowing the optics to be centered as fast as f/2.7. This pattern is recommended for general use because it can be used with the fastest telescopes you are likely to come across.
A pattern of nine concentric circles is available that spans 10 degrees and will reach the edge of the f/5.7 optic. This pattern is recommended for viewfinders at this focal ratio or slower. Because the laser light is spread over a smaller area, it is brighter than the square grid pattern, and this makes it particularly useful with Cassegrain sights, where the impact of the pattern is sometimes examined on mirror surfaces. The projected pattern is only seen in light that is scattered by dust, dirt, or optical harshness, so a brighter pattern is better, especially if the mirrors are very clean.
A cross and circle "scope" pattern is available that spans 10 degrees. It is useful for conventional non-Barlowed Newtonian primary collimation, where the primary is adjusted to return the reflected center laser beam back to the collimator laser aperture. The intersection of the crosshairs makes it easier to see when the return beam is centered on the collimator face.
Our expert comment:
This is the new version ('NV') with a thicker thread. The disk fits all Howie Glatter/Starlight Instruments lasers, which also have a new thread ("NV" in the item number). If you have an older version of the laser (before 2020), please contact us before ordering.
This is the new version ("NV") with thick thread. The accessory fits all Howie Glatter/Starlight Instruments laser collimators, which also have a new thread ("NV" in the item number). If you own an older version of the laser (before 2020), please contact us before placing your order.