| 摘要 |
PURPOSE:To record a signal even when the quantity of light of a light beam having a wavelength lambda2 is small and to enable the recording with high density by recording the signal in modulating both light beam of a wavelength lambda1 having a quantity of light which is unable to record a signal on a recording carrier and the light beam of the wavelength lambda2 which is shorter than the light beam of the wavelength lambda1. CONSTITUTION:The system is composed of a light source 1, an SHG element 2, a coupling lens 3, a 1/4 wavelength plate 4, a polarization beam splitter 5, a convergent lens 6, the recording carrier 7, a motor 8, a convex lens 9, a cylindrical lens 10, a photodetector 11 and a transfer base 13. The light beam of the wavelength lambda1 of the light quantity which is unable to record a signal on the recording carrier 7 and the light beam of the wavelength lambda2 are both modulated in accordance with a signal to be recorded, and the recording carrier 7 is irradiated with these beams, and then a focus control is performed by detecting a focus shift of the light beam of the wavelength lambda2 on the recording carrier 7 from reflected light of the light beam of the wavelength lambda2 from the recording carrier 7. Consequently, a light beam spot of the wavelength lambda2 on the recording carrier 7 is always brought under the most contracted state. By this method, a good quality signal is recorded and reproduced with high density. |
