Phase shift device and laser apparatus utilizing the same

A laser apparatus employing a phase shift device, comprising:

• a laser light source for emitting a laser beam from a light emitting face thereof;
• optical means for condensing the laser beam from the laser light source onto an image surface;
• and
• a phase shift device positioned proximate a position conjugate with the light emitting face, said device including a first area transparent to the laser beam and a ring-shaped second area provided around said first area, said second area having a phase difference of 180.degree. relative to light passing through said first area, said second area shifting the phase of the laser beam passing therethrough by a predetermined phase difference with respect to the laser beam passing through said first area such that light emerging from the phase shift device has a narrowed intensity distribution on said image surface.

A laser apparatus employing a phase shift device, comprising:

• a laser light source for emitting a laser beam which is converged through a waisted region;
• optical means for condensing the laser beam from the laser light source onto an image surface;
• and
• a phase shift device positioned proximate the waisted region of the laser beam, said device including a first area transparent to the laser beam and a ring-shaped second area provided around said first area, said second area having a phase difference of 180.degree. relative to light passing through said first area, said second area shifting the phase of the laser beam passing therethrough by a predetermined phase difference with respect to the laser beam passing through said first area such that light emerging from the phase shift device has a narrowed intensity distribution on said image surface.

A laser scanning apparatus employing a phase shift device, comprising:

• a laser light source for emitting a laser beam;
• optical means for condensing the laser beam from the laser light source onto an image surface;
• a phase shift device arranged in a position between the laser light source and the optical means and including a first area transparent to the laser beam and a ring-shaped second area provided around said first area, said second area having a phase difference of 180.degree. relative to light passing through said first area, said second area shifting the phase of the laser beam by a predetermined phase difference relative to the laser beam passing through the first area, the second area being provided around the first area, such that the laser beam emerging from the device has a narrowed intensity distribution on said image surface;
• and
• deflecting means for scanningly deflecting the laser beam from the phase shift device.

A laser apparatus employing a phase shift device, comprising:

• a laser light source for emitting a laser beam;
• first optical means for condensing the laser beam from the laser light source;
• a phase shift device arranged in a position where the laser beam is condensed by the first optical means and including a first area transparent to the laser beam and a ring-shaped second area provided around said first area, said second area having a phase difference of 180.degree. relative to light passing through said first area, said second area shifting the phase of the laser beam by a predetermined phase difference relative to the laser beam passing through the first area, the second area being provided around the first area, such that the laser beam emerging from the device has a narrowed intensity distribution on an image surface;
• and
• second optical means for condensing the laser beam from the phase shift device onto said image surface.

A light pick-up apparatus employing a phase shift device, comprising:

• a laser light source for emitting a laser beam;
• first optical means for condensing the laser beam from the laser light source;
• a phase shift device arranged in a position where the laser beam is condensed by the first optical means and including a first area transparent relative to the beam and a ring-shaped second area provided around said first area, said second area having a phase difference of 180.degree. relative to light passing through said first area, said second area shifting the phase of the laser beam by a predetermined phase difference relative to the laser beam passing through the first area, the second area being provided around the first area, such that the laser beam emerging from the device has a narrowed intensity distribution on a recording medium;
• second optical means for condensing the laser beam from the phase shift device onto said recording medium;
• and
• detecting means for detecting the laser beam from the recording medium.

A laser scanning apparatus employing a phase shift device, comprising:

• a laser light source for emitting a laser beam;
• optical means for condensing the laser beam from the laser light source onto an image surface;
• and
• a phase shift device arranged in a position between the laser light source and the optical means and including a first area transparent to the laser beam and a ring-shaped second area provided around said first area, said second area having a phase difference of 180.degree. relative to light passing through said first area, said second area shifting the phase of the laser beam by a predetermined phase difference relative to the laser beam by a predetermined phase difference relative to the laser beam passing through the first area, the second area being provided around the first area, such that the laser beam emerging from the device has a narrowed intensity distribution on said image surface.