INTERVAL DETECTING METHOD, INTERVAL CONTROLLER, INFORMATION RECORDING AND REPRODUCING DEVICE AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To maintain prescribed recording density by providing periodic patterns having different periods on a recording medium and detecting the interval between a probe and a sample so as to be able to obtain a prescribed resolution even when the variation of shapes of light probes and a cause changing the resolution of the light probe such as secular change and so forth are present to control the interval by the detected result. SOLUTION: Patterns 2, 3 whose periodic pattern are different are formed on a substrate 1. The substrate 1 is made of transparent material of SiO2 or the like and the patterns 2, 3 are made of opaque material of Al or the like. The radiant light from a semiconductor laser 4 is also projected on the patterns 2, 3 because the substrate 1 is transparent. The light diffracted or scattered by the patterns 2, 3 is picked up from the aperture part of a light probe 6 to propagate in an optical fiber 7 to be converted into an electric signal in a photodetector 11. Then, the interval between the light probe 6 and the substrate 1 is detected by performing the frequency analysis of the detected signal.