Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4850673 | Optical scanning apparatus which detects scanning spot focus error | Henricus M. M. Kessels | 1989-07-25 |
| 4800547 | Optical record carrier scanning apparatus with scanning beam focus error detection | Henricus M. M. Kessels | 1989-01-24 |