| 摘要 |
PURPOSE:To distinguish positively an alignment pattern on the specimen and the reference pattern, by installing independently an optical system forming a special image of the reference pattern for positioning. CONSTITUTION:An alignment pattern 2 is irrodiated downward by light-quide 4, illuminating lens 5 and half-mirror 6 through an objective lens 3 and an image developed by the lens 3 of the image of the alignment pattern 2 becomes an intermediate image 2a of the lens 3. On the other hand, a glass dry plate 10 forming an illuminating lens 8 and the reference pattern 9 on the optical axis of an infrared light emission diode 7 and a projecting lens 11 are installed and by irradiating the glass plate 10 forming the reference pattern 9 by the diode 7 and the lens 8, an image of the reference pattern 9 by the projecting lens 11 is reflected by a reffecting mirror 6 and projected on the intermediate image 2a of the pattern 2. Overlapped special image 9a and intermediate image 2a are projected on a detecting element by relay lens 12, prism 13 for correction of a position difference. |
