| 摘要 |
PURPOSE:To improve the output characteristic and the defocus characteristic by increasing the image forming performance of a line sensor in the arranging direction of a photodetector cell more than the image forming performance in the direction orthogonal to the arranging direction so as to decrease the incident angle of light and the reflection angle of light from an optical recording medium to the line sensor. CONSTITUTION:An optical recording medium 2 is provided to an optical card 1, and in order to reproduce the information recorded on the optical recording medium 2, a light source 3 such as a light emitting diode irradiating a lighting light and the line sensor 4 receiving a reflected light from the recording medium face, so-called read light, are provided. In order to form the image of the read light on a photodetection part 5 of the line sensor 4, an image forming lens 6 is arranged between the optical card 1 and the line sensor 4. In the image forming lens 6, the image forming performance in the arranging direction Z of a photodetector cell S of the line sensor 4 is increased more than that in the direction X orthogonal to the direction Z. |
