Hole gratings for laser damage testing

The use of hole gratings in small-spot laser damage testing is discussed. Several forms of hole gratings are discussed, and some criteria are suggested for the design and use of these gratings. The variables and considerations addressed include: the number, separation, and arrangement of the holes; the shape, size, and orientation of each hole; the intensity variation over the array of holes; the transmission of the array; the number and relative intensities of the several maxima; and the extent to which the array exactly reproduces the intensity distribution which would have been produced without using the array. Results of damage testing on metals are presented for two of the gratings, and recommendations for an ideal grating are made.