Claims
- 1. A position detection apparatus comprising:
- a substrate having a diffraction grating;
- means for supplying illuminating flux;
- means for splitting said illuminating flux into two luminous fluxes;
- means for modulating the frequency of at least one of said luminous fluxes by a predetermined value in order to obtain two luminous fluxes having frequencies that are different from each other;
- means for causing the last-mentioned luminous fluxes to impinge upon said substrate in such a manner that they pass along independent optical paths and then are incident on said diffraction grating from different directions;
- means for adjusting an intersection angle made by said two luminous fluxes incident on said diffraction grating;
- means for adjusting the direction of arrangement of interference fringes generated on said diffraction grating by said two incident luminous fluxes, the last-mentioned adjusting means being disposed in at least one of said optical paths and including optical means which can be displaced for shifting a luminous flux received thereby in two directions orthogonal to each other; and
- means for photo-electrically detecting an optical beat signal due to said interference fringes.
- 2. A position detection apparatus according to claim 1, wherein said optical means includes a parallel plane plate whose inclination angle can be varied about two axes orthogonal to each other.
Priority Claims (2)
Number |
Date |
Country |
Kind |
1-48295 |
Feb 1989 |
JPX |
|
1-142377 |
Jun 1989 |
JPX |
|
Parent Case Info
This is a continuation of application Ser. No. 482,557 filed Feb. 21, 1990, now abandoned.
US Referenced Citations (3)
Foreign Referenced Citations (2)
Number |
Date |
Country |
62-261003 |
Nov 1987 |
JPX |
63-283129 |
Nov 1987 |
JPX |
Continuations (1)
|
Number |
Date |
Country |
Parent |
482557 |
Feb 1990 |
|