Plane grating polarizing beamsplitter

Claim 2

A polarizing beamsplitter placed in the optical path of a source of coherent radiation of waveIengthj?, said beamsplitter formed as a surface relief transmission grating having a grating period d equal to said wavelength ? divided by a value of between 1.2 and 1.5, said grating essentiallycompletely diffracting incident S polarized light and transmitting P polarized light, said grating placed in the optical path of said coherent radiation so that said radiation is incident an angle .THETA.i and diffracted at an equal angle .THETA.d, .THETA.i ? .THETA.d ? 45°.

Claim 3

The beamsplitter of claim 1 wherein d=

Claim 4

The beamsplitter of claims 1 or 2 wherein said grating is formed on the surface of a light-transmitting member.

Claim 5

An optical reader system for reading the information content of a recording surface in conjunction with a detector device comprising, in combination, a laser light source which generates an S polarized beam of wavelength A, a polarizing beamsplitter formed as a transmission type plane linear grating having a grating period d equal to said wavelength ? divided by a value of between 1.2 and 1.5, said grating essentially completely diffracting incident S polarized light and transmitting P polarized light, said grating placed in the optical path of said S polarized light beam so that the light beamis incident an angle .THETA.i and diffracted at an equal angle .THETA.d, .THETA.i ? .THETA.d ?45°, a wave retardation device placed in the optical path so as to convert the linearly polarized diffracted beam into a circularly polarized beam, and a lens element placed in the optical path between said retardation device and the recording surface so as to focus said beam onto the appropriate surface area whereby said beam is reflected from said recording surface through said lens and through said retardation device, thereby being converted into a P polarized wave which is essentially completely transmitted through said grating onto said detector device.

Claim 6

An optical reader system for reading the information content of a recording surface in conjunction with a detector device comprising, in combination, a laser light source which generates an S polarized beam of wavelength A, a polarizing beamsplitter formed as a transmission type plane linear grating having a grating period d equal to said wavelength ? divided by a value of between 1.2 and 1.5, said grating essentially completely diffracting incident S polarized light and transmitting P polarized light, said grating placed in the optical path of said S polarized light beam so that the light beamis incident an angle .THETA.i and diffracted at an equal angle .THETA.d, .THETA.i ? .THETA.d ?45°, a wave retardation device placed in the optical path so as to convert the linearly polarized diffracted beam into a circularly polarized beam, and a lens element placed in the optical path between said retardation device and the recording surface so as to focus said beam onto the appropriate surface area whereby said beam is reflected from said recording surface through said lens and through said retardation device, thereby being converted into a P polarized wave which is essentially completely transmitted through said grating onto said detector device.

Claim 7

The system of claim 4 wherein d=

Claim 9

The system of claim 4 further including means for increasing the power of said laser light so as to operate in a write mode as well as read mode and further including means of tracking said beamsplitter arrangement across said recording surface.

Claim 10

The system of claim 4 wherein light source is gas laser.

Claim 11

The system of claim 4 wherein the light source is a diode laser.

Claim 12

The system of claim 9 further including a second plane linear grating having the same period, said second grating, in conjunction with said lens serving to compensate for the wavelength shift of said laser light.

Claim 13

The system of claim 4 further including a phase retardation plate between the source of laser light and the grating.

Claim 14

The system of claim 4 wherein said grating is formed as a sinusoidal surface relief grating.

Claim 15

The system of claim 4 wherein said recording surface com-prises an optical disc memory storage device.