Patent ID: 7859973

Claim:
A method of recording a hologram, on a hologram recording apparatus having a pair of optical systems oppositely arranged spaced both on an optical axis sandwiching a hologram record carrier, the one pair of optical systems being made up by a reference-beam optical system having a reference-beam objective lens through which a reference beam is to be exited toward the hologram record carrier and a signal-beam optical system having a signal-beam objective lens through which a signal beam is to be exited toward the hologram record carrier, the signal-beam optical system including a spatial light modulator that produces the signal beam by modulation from the reference beam transmitted through the hologram record carrier according to record information, to record information by forming a diffraction grating through oppositely irradiating the signal beam and the reference beam to the hologram record carrier, the method comprising: a step of focusing the reference beam at a first numerical aperture from a first effective diameter by means of the reference-beam objective lens; a step of separating the reference beam in a part on the optical axis and a neighborhood thereof to thereby produce from the reference beam a recording reference beam to passes through the hologram record carrier at a second numerical aperture smaller than the first numerical aperture from a second effective diameter smaller than the first effective diameter by means of the reference-beam objective lens of the reference-beam optical system, and allowing the recording reference beam to exit coaxially to the reference beam; and a step of not allowing only the recording reference beam to exit toward the hologram record carrier by means of the signal-beam optical system.