Patent ID: 7606117

Claim:
An information recording and reproducing apparatus comprising: a recording medium comprising at least a substrate, a reflection layer disposed on the substrate, and a recording layer disposed so as to interpose the reflection layer between the substrate and the recording layer; and a near-field optical head, disposed close to said recording medium, for irradiating said recording medium with near-field light to effect recording and reproduction of information, wherein said near-field optical head includes a light-blocking metal film which comprises a dielectric base material provided with a small opening and which is disposed opposite to the reflection layer disposed on the substrates, so that the light-blocking metal film and the reflection layer constitute an optical resonator, to increase intensity of the near-field light, wherein the optical resonator satisfies the following resonance condition: 4π L/λ+φ 1+φ2=2 mπ, wherein L represents an optical path between a bottom surface, of said near-field optical head, at which the light-blocking metal film is disposed; λ represents a wavelength in a vacuum of a light source used in said near-field optical head; φ 1 represents a due to reflection by the light-blocking metal film; φ 2 represents a phase shift due to reflection by the reflection layer; and m represents a positive integer.