Record carrier for a television signal

Claim 1

A record carrier of the type on which a television signal is stored in tracks in the form of a radiation modulating information structure of constant track width recorded along an average track path, which structure modulates the phase of a read beam of radiation, the stored television signal comprising a first carrier wave which is frequency modulated with the luminance information, and further carrier waves which are modulated with additional information, the improvement wherein the tracks of the information structure are continuous tracks which in the plane of said structure exhibit undulation transverse to the average track path, the amplitude, frequency and phase characteristics of said undulation being determined by both the first and the additional modulated carrier waves, the undulation amplitude being substantially smaller than the period of the track structure in a direction transverse to the average track path, the tracks comprising a means for providing a difference in optical pathlength in the read beam which is approximately equal to an odd multiple of a quarter of the wavelength of the read beam of radiation.

Claim 6

An apparatus for reading a record carrier on which a television signal is stored in continuous tracks in the form of radiation modulating radial undulations of constant track width recorded along an average track path which structure is capable of modulating the phase of radiation, comprising a radiation source which supplies a read beam of radiation, an objective system for transferring radiation from the radiation source via the record carrier to a radiation-sensitive detection system, which converts the read beam which is modulated by the information structure into an electric signal, wherein the information detection system comprises two adjacent radiation-sensitive detectors which are disposed in the effective exit pupil of the objective system and provide electrical signals, an imaginary separating line intermediate the detectors, if projected on the plane of the information structure, being parallel to the average track path of the record portion being scanned by said read beam of radiation, and a differential amplifier at whose output the information signal is available having input terminals connected to the electrical signals from the detectors.

Claim 7

An apparatus for reading a record carrier on which a television signal is stored in continuous tracks in the form of radiation modulating radial undulations of constant track width recorded along an average track path which structure is capable of modulating the phase of radiation, comprising a radiation source which supplies a read beam of radiation, an objective system for transferring radiation from the radiation source via the record carrier to a radiation-sensitive detection system, which converts the read beam which is modulated by the information structure into an electric signal, wherein the information detection system comprises two adjacent radiation-sensitive detectors which are disposed in the effective exit pupil of the objective system and provide electrical signals, an imaginary separating line intermediate the detectors, if projected on the plane of the information structure, being parallel to the average track path of the record portion being scanned by said read beam of radiation, and a differential amplifier at whose output the information signal is available having input terminals connected to the electrical signals from the detectors.