A holographic lens is used in conjunction with a pulsed ruby laser for machining single and multiple spots on a 0.12-µm thin film of tantalum deposited on glass. Spot sizes as small as 14 µm have been obtained with hologram diffraction efficiencies as great as 30%. Imaging of two spots separated by 3.18 mm has resulted in the simultaneous machining of two 30-µm spots having equal intensity and spot shape. The resolution that has been obtained with the high powered laser and the observed durability of the dichromated gelatin holograms for very high energy densities are encouraging and suggest a number of possible applications.
J. M. Moran, "Laser Machining with a Holographic Lens," Appl. Opt. 10, 412-415 (1971)