| 摘要 |
PURPOSE:To prevent the variance in the coating state of photoresist from affecting the quality of an original glass disc by measuring the reflectance of the photoresist on said disc and controlling a developing time in accordance with the reflectance. CONSTITUTION:The laser power from a light source 2 is made constant and the laser light is on-off modulated by the signal from an information signal source 5 by an optical modulating element 4. The modulated beam thereof is conducted via a lens 6, a prism 7, a mirror 8 and an objective lens 9 to an original disc 1, thereby exposing the photoresist. The reflected beam from the disc 1 is conducted to a photodetector 3 via the lens 9, the mirror 8 and the prism 7. This turns out that the voltage level obtd. with the photodetector 3 when the beam is on by the element 4 indicates reflectance. The developing time is controlled by utilizing the predetermined characteristics of reflectance-developing time. |
