| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that since laser light for crystallization and light for distance measurement are both guided to the same optical axis, not only both the lights tend to interfere with each other, but also they are reflected or transmitted when they are transmitted through a half-mirror causing a decrease in intensity. SOLUTION: An apparatus has an elevation driving device 30 which moves a stage 10 relatively to a reticle 21 and an objective 3, a distance meter 31 which is provided at a specified distance L from a pulse laser 4 and measures a distances (h) to the irradiated surface of an irradiated body 5 one after another to output detected values hn, and a basic control value setting means which outputs a basic control value H corresponding to a proper distance between the irradiated body 5 and the objective 3; and difference valuesΔn between the basic control value H and the detected values hn are found one after another, a control difference valueδbased upon the difference between a last found difference valueΔn-1 and a current found difference valueΔn is found and outputted after being delayed by a time needed for movement by the specified distance L, and the elevation driving device 30 is driven according to the control difference valueδto control the distance. COPYRIGHT: (C)2004,JPO
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