Hologram recorder

Abstract

A hologram recorder is provided for recording a hologram on a hologram recording medium by interference of a recording beam with a reference beam. The recorder includes a light source for outputting coherent light to be split into the recording beam and the reference beam; a spatial light modulator for modulating the recording beam into a form representing information to be recorded; an objective lens for outputting the recording beam; and a phase shift mask provided at a light entering surface of the spatial light modulator. The mask is configured to allow the recording beam to pass through, and also to partially shift the phase of the recording beam passing through the mask.

Description

technical field [0001] The present invention relates to a hologram for recording holograms in a holographic recording medium. Background technique [0002] A conventional hologram is disclosed in, for example, JP-A-2002-216359. This holographic recorder has such Figure 4 The basic structure shown. Specifically, a laser beam emitted by a laser source (not shown) is divided into a recording beam S and a reference beam R. Referring to FIG. Next, the recording beam S is modulated by the spatial light modulator 500A into a form representing the information to be recorded, and then passes through the relay lenses 700A, 700B and then the objective lens 700 before it reaches the recording layer 91 of the holographic recording medium B. On the other hand, reference beam R is directed to holographic recording medium B by recording galvanometer mirror 900 and condenser lenses 100A, 100B, and intersects recording beam S on recording layer 91 of holographic recording medium B. As a r...

AI Technical Summary

Problems solved by technology

[0004] However, as will be described in detail in the following paragraphs, there is a problem in the conventional hologram in that as the number of effective pixels of the spatial light modulator 500 increases, the design conditions for the optical system including, for example, the objective lens become more and more demanding

[0007] Although not specifically shown, there may be another case in which the pixel pitch is reduced without changing the entire pixel area of ​​the spatial light modulator, so as to be consistent with Figure 4 Compared with the case in , the number of effective pixels relative to the recording beam is increased

Also in this case, the result is an increase in the distance between the optical axis and the ±1st order diffraction due to the increase in the diffraction angle with the pixel pitch at the exit surface of the spatial light modulator

This means that even if the pixel pitch is reduced, the effective aperture of the objective must be increased even more

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