Aberration correcting optical unit, optical pickup apparatus, and information recording/reproducing apparatus

Abstract

An aberration correcting optical unit includes an optical element for causing a phase change to light passing therethrough by the application of voltage and electrode layers for applying voltages to the optical element. The optical element is sandwiched between the electrode layers. At least one of the electrode layers includes a plurality of electrodes which are electrically isolated from one another. The plurality of electrodes are disposed such that an electric field generated in a portion of the optical element corresponding to a portion between the plurality of electrodes is larger than a predetermined intensity when a predetermined voltage is applied to the optical element.

1 - 16 . (canceled)  
     
     
         17 . An aberration correcting optical unit disposed in an optical path of an optical system for irradiating a recording medium with a light beam emitted from a light source and for guiding a reflected light beam reflected by said recording medium, for correcting aberration occurring in said reflected light beam, comprising: 
 a liquid crystal element for causing a phase change to light passing therethrough by the application of voltage;    first and second electrode layers opposing to each other, said first and second electrode layers sandwiching said liquid crystal element;    said first electrode layer includes a plurality of divided electrodes electrically isolated from one another by gaps in the same plane, and    an insulating layer disposed between said liquid crystal element and said first electrode layer, said insulating layer having a thickness larger than the gaps of said first electrode layer.    
     
     
         18 . An aberration correcting optical unit according to claim  1 , wherein said insulating layer has a thickness larger than a thickness of said liquid crystal element.  
     
     
         19 . An aberration correcting optical unit according to claim  1 , further comprising 
 a liquid crystal alignment layer provided between said liquid crystal element and said insulating layer.    
     
     
         20 . An aberration correcting optical unit according to claim  1 , further comprising: 
 a second insulating layer disposed between said liquid crystal element and said second electrode layer,    wherein said second electrode layer includes a plurality of divided electrodes electrically isolated from one another by gaps in the same plane, and said second insulating layer having a thickness larger than the gaps of said second electrode layer.    
     
     
         21 . An aberration correcting optical unit according to claim  4 , further comprising a liquid crystal alignment layer provided between said liquid crystal element and said second insulating layer.  
     
     
         22 . An optical pickup apparatus including the aberration correcting optical unit according to claim  1 , comprising: 
 a light source for emitting a light beam;    an optical system for irradiating a recording medium with the light beam emitted from said light source and for guiding a reflected light beam reflected by said recording medium; and    a photodetector for detecting said reflected light beam.