Useful for aligning the returning beam on collimator face.
Removable diffractive optical element for use in Glatter Holographic Collimators.
Howie Glatter Holographic 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.
The diffractors are individually fit to their collimators for maximum alignment accuracy, so if you have one of my holographic collimators and know someone else who has one, be careful not to switch diffractors. If switched, 15 second alignment accuracy in the holographic mode is likely to be lost, however, they will still fall within the several arc minute alignment tolerance of most other laser collimators. Because there are some collimating situations in which the diffracted pattern is unnecessary or unwanted, or maximum power in the central beam may be desired, the diffractor unscrews from the laser aperture, converting the holographic collimator to single beam mode. When it is screwed back it retains its alignment accuracy.”
Accurate and Precise. What more could you ask?