摘要
Versatile computer programs capable of simulating near‐contact images from arbitrary objects and illumination were reported. Their capability was demonstrated in examples of combinations of different types of object and illumination. From the specific examples, we were able to derive certain general rules: (1) Polychromatic illumination is always better than monochromatic illumination. (Besides observing the examples given above, polychromatic illumination also helps when standing waves in photoresist are considered.) (2) Negative masks are easier to print than positive ones. Note that a negative mask in the sense of optical diffraction means smaller dimension for transparent parts of the mask. (3) Some well designed irregularities in the mask pattern improves the image. (4) The effective depth tolerance is between the limits set by the focussing effect and the image spreading effect. (5) Holographic mask should relax flatness and exposure tolerance. Copyright © 1974 Society of Plastics Engineers, Inc.