Patent ID: 8830809

Claim:
An optical information recording device which causes an interference between a signal light and a reference light to form an interference pattern and records the interference pattern on a recording medium, said optical information recording device comprising: a first laser beam source which emits a first laser beam; a signal light optical system which forms the signal light from the first laser beam and causes the signal light to enter the recording medium; a reference light optical system which forms the reference light from the first laser beam and causes the reference light to enter the recording medium; a second laser beam source which emits a second laser beam with a wavelength different from a wavelength of the first laser beam; a third laser beam source which emits a third laser beam with a wavelength different from the wavelength of the first laser beam; a first measuring light optical system which forms a first measuring light from the second laser beam and causes the first measuring light to enter the recording medium; a second measuring light optical system which forms a second measuring light from the third laser beam and causes the second measuring light to enter the recording medium; a first light receiving unit which receives a reflected light of the first measuring light which enters the recording medium; a second light receiving unit which receives a reflected light of the second measuring light which enters the recording medium; a detection unit which detects a focus-direction height of the recording medium based on a received signal received by said first light receiving unit and a received signal received by said second light receiving unit; a focus adjustment unit which adjusts a relative distance between an object lens of said signal light optical system and the recording medium; and a control unit which controls said focus adjustment unit so that the relative distance between the object lens of said signal light optical system and the recording medium is adjusted according to the focus-direction height of the recording medium detected by said detection unit.