| 摘要 |
PURPOSE:To enable stable control of development by disposing a lens which converges and irradiates laser light on one side of the original plate of a glass master, and disposing an image sensor in the part on the other side where the light of zero order and the light of 1st order overlap. CONSTITUTION:Laser light 9 is converges with a lens 13 onto the photoresist 2 on a glass substrate 3. The signal track recorded in the resist 2 acts as a phase grating and the laser light is diffracted. A black and white pattern is detected with an image sensor 14 disposed in accordance with the part where the light of zero order and the light of 1st order overlap, and the AC signal corresponding to the degree of development is thus obtained. The signal is amplified with an operational amplifier 15, whereby a control signal is obtained. The AC signal can be amplified more stably as compared with a DC signal and since the sensor 14 detects contrast, the development is controlled stably without receiving the influence of the fluctuation in the total quantity of light. |
