| 摘要 |
PURPOSE:To improve measuring conditions by automatically varying the opening area of a measuring window prior to the measurement to set the measuring window matching the size of the pupil. CONSTITUTION:A pupil section signal 17a is integrated with an integration circuit 18 and an offset voltage Vo is applied to a pupil lateral diameter signal 19a which is memorized and held in a sample hold circuit 19 after amplified with an amplifier 30. The output signal 30a is inputted into a comparator 32 while into a comparator 34 via a code inverter 33. A saw tooth wave 31a is inputted into other input ends of the two respective comparators. When outputs of the comparators 32 and 34 are ANDed with an AND gate 35, a signal 35a has a lateral diameter corresponding to the pupil diameter of the pupil section signal 17a. The same results are obtained with the vertical diameter. Thus, the measuring window is obtained automatically to match the size of the pupil thereby improving measuring conditions. |
