Abstract: An information signal recording medium of rotary type has a flat surface with first succession of pits formed therein as respective concavities in response to a first signal and with second succession of pits formed therein as respective concavities in response to a second signal. The second succession of pits are formed at positions substantially intermediate between the centerlines of adjacent tracks formed by the first succession of pits. Each pit of the first succession of pits and each pit of the second succession of pits respectively have widths W1 and W2 and depths D1 and D2, wherein the relationships between the widths and said depths are so selected that the levels L1 and L2 of the first and second signals which are reproduced when the first and second succession of pits are traced and thereby reproduced by reproducing means will be such that the level L1 is greater than the level L2, and the difference between the levels L1 and L2 will be greater than a specific level difference.

Abstract: An information signal recording medium of rotary type has a flat surface with successions of pits formed therein as respective concavities in response to an information signal. The successions of pits constitute respective circular tracks of a specific pitch. Each it is formed with a width, equal to the width of a track, which is substantially equal to or greater than said pitch of the track.

Abstract: An optical recording apparatus comprises a light source for emitting a light beam, a modulator for modulating the light beam with a signal to be recorded, and an optical system for conducting the light beam thus modulated through a specific light path. The light beam has a specific cross-sectional shape which is projected onto a recording medium. The optical system also includes a restricting plate having a slit or hole for restricting the cross-sectional shape of the modulated light beam to the specific shape. A pair of light detectors are irradiated by the modulated light beam of the restricted cross-sectional shape to detect the intensities of the light beam in the vicinity of two end parts. Any difference between the outputs of the two light detectors control the optical system, in response to the detected difference, so that the light intensity distribution of the modulated beam in the restricted cross-sectional shape is maintained symmetrical with respect to the center of light distribution.

Abstract: The inventive system optically records information signals on a recording disc. A light source, such as a laser beam, for example, emits a light which is modulated in conformance with an information signal that is to be recorded. An optical system converts this light into a beam having a large width in the longitudinal direction of a track formed on the recording disc. There is a small beam dimension in the transverse direction of the track. A slit plate within the optical system limits the width of the light to cause a constant beam width in the transverse direction of the track. A focusing lens receiving, as incident light, such a limited light beam forms a light spot on the recording disc which is small in the longitudinal direction of the track and large in the transverse direction of the track. The light spot forms a plurality of pits in the upper surface of the recording disc.