Optical data retrieval system using multi-spectral light sources

Claim 2

An optical data medium reading system comprising, a transparent substrate carrying a reflective information layer encoding data by means of pits in a reflective field, the medium being transmissive through the pits to a probe beam of a first wavelength, the medium having different reflectivity from the field than from the pits to a probe beam of a second wavelength, and detector means positioned to receive said first and second wavelengths after impingement with the information layer for converting said wavelengths to electrical signals.

Claim 3

An optical data card reading system comprising, a data card having an optical data recording medium with a selectively reflective surface layer overlying a transparent substrate, and data being encoded by pits in the reflective surface layer, a first probe beam source positioned on one side of the medium for directing a first beam to impinge on pits in the medium, said first beam having a first characteristic wavelength which is reflected from the surface layer, a second probe beam source positioned on the opposite side of the medium from the first light source for directing a second beam through said substrate and said same pits as the first beam, said second beam having a second characteristic wavelength, beam detector means for intercepting the first and second beams after impingement with the pits and for converting said beams into corresponding electrical signals.

Claim 4

An optical data card reading system comprising, a data card having an optical data recording medium with a selectively reflective surface layer overlying a transparent substrate, and data being encoded by pits in the reflective surface layer, a first probe beam source positioned on one side of the medium for directing a first beam to impinge on pits in the medium, said first beam having a first characteristic wavelength which is reflected from the surface layer, a second probe beam source positioned on the opposite side of the medium from the first light source for directing a second beam through said substrate and said same pits as the first beam, said second beam having a second characteristic wavelength, beam detector means for intercepting the first and second beams after impingement with the pits and for converting said beams into corresponding electrical signals.

Claim 5

The system of claim 2 wherein said first and second sources are disposed on opposite sides of said card in mirror image relation.

Claim 6

The system of claim 2 wherein said first characteristic wavelength is 830 nanometers.

Claim 7

The system of claim 2 wherein said second characteristic wavelength is 1200 nanometers.

Claim 8

The system of claim 2 further defined by first and second scanning mirror means disposed to reflect light from said first and second sources for directing said first and second beams onto said pits and wherein said beam detector means comprises a CCD array.

Claim 9

An optical data retrieval system comprising, an optical data storage medium having a transparent substrate carrying a reflective information layer encoding data by differences in reflectivity between recorded data pits and the surrounding field, the higher reflective areas having high optical reflectivity to a probe beam of a first wavelength and high optical transmissivity to a probe beam of a second wavelength and the lower reflective areas having low optical reflectivity to the probe beam of the first wavelength and low optical transmissivity to the probe beam of the second wavelength, a first probe beam source positioned on one side of the medium to direct a first wavelength at pits on the reflective information layer of the medium, a second probe beam source positioned on the opposite side of the medium from the first light source to direct a second wavelength through the medium to the same pits on the information layer as the first light source, and detector means positioned to receive said first and second wavelengths after impingement with the information layer for converting said wavelengths to electrical signals.

Claim 10

An optical data retrieval system comprising, an optical data storage medium having a transparent substrate carrying a reflective information layer encoding data by differences in reflectivity between recorded data pits and the surrounding field, the higher reflective areas having high optical reflectivity to a probe beam of a first wavelength and high optical transmissivity to a probe beam of a second wavelength and the lower reflective areas having low optical reflectivity to the probe beam of the first wavelength and low optical transmissivity to the probe beam of the second wavelength, a first probe beam source positioned on one side of the medium to direct a first wavelength at pits on the reflective information layer of the medium, a second probe beam source positioned on the opposite side of the medium from the first light source to direct a second wavelength through the medium to the same pits on the information layer as the first light source, and detector means positioned to receive said first and second wavelengths after impingement with the information layer for converting said wavelengths to electrical signals.

Claim 11

The optical data retrieval system of claim 7 wherein said optical data medium has high reflectivity recorded data pits and a low transmissivity surrounding field.

Claim 12

The optical data retrieval system of claim 7 wherein said optical data medium has low reflectivity data pits and a high reflectivity surrounding field.

Claim 13

The optical data retrieval system of claim 7 wherein said first wavelength is approximately 830 nm.

Claim 14

The optical data retrieval system of claim 7 wherein said second wavelength is approximately 1200 nm.

Claim 15

The optical data retrieval system of claim 7 wherein light of the first and second wavelengths impinge on the same pits on the medium simultaneously.

Claim 16

The optical data retrieval system of claim 7 wherein light of the first and second wavelengths alternately impinge on the same pits on the medium.

Claim 17

The optical data retrieval system of claim 7 wherein said detector means comprises separate detectors for each wavelength.

Claim 18

The optical data retrieval system of claim 7 wherein said detector means comprises a common detector for both wavelengths.

Claim 19

The optical data retrieval system of claim 7 wherein said optical data medium is a data card having a transparent substrate and carrying a reflective recording area in which data is recorded by pits in the reflective area.

Claim 20

The optical data retrieval system of claim 7 wherein said optical data medium is a data card having a transparent substrate and carrying a reflective recording area on which reflective data pits have been prerecorded.

Claim 21

An optical data retrieval system comprising, an optical data storage medium having a transparent substrate carrying a reflective information layer encoding data by differences in reflectivity between recorded data pits and the surrounding field, the higher reflective areas having high optical reflectivity to a probe beam of a first wavelength and optical transmissivity to a probe beam of a second wavelength and the lower reflective areas having low optical reflectivity to the probe beam of the first wavelength and higher optical transmissivity to the probe beam of the second wavelength. a first probe beam source positioned on one side of the medium to direct a first wavelength at pits on the reflective information layer of the medium, a second probe beam source positioned on the opposite side of the medium from the first light source to direct a second wavelength through the medium to the same pits on the information layer as the first light source, and detector means positioned to receive said first and second wavelengths after impingement with the information layer for converting said wavelengths to electrical signals.

Claim 22

An optical data retrieval system comprising, an optical data storage medium having a transparent substrate carrying a reflective information layer encoding data by differences in reflectivity between recorded data pits and the surrounding field, the higher reflective areas having high optical reflectivity to a probe beam of a first wavelength and optical transmissivity to a probe beam of a second wavelength and the lower reflective areas having low optical reflectivity to the probe beam of the first wavelength and higher optical transmissivity to the probe beam of the second wavelength. a first probe beam source positioned on one side of the medium to direct a first wavelength at pits on the reflective information layer of the medium, a second probe beam source positioned on the opposite side of the medium from the first light source to direct a second wavelength through the medium to the same pits on the information layer as the first light source, and detector means positioned to receive said first and second wavelengths after impingement with the information layer for converting said wavelengths to electrical signals.

Claim 23

The optical data retrieval system of claim 18 wherein said optical data medium has low reflectivity and high transmissivity recorded data pits.

Claim 24

The optical data retrieval system of claim 18 wherein said optical data medium has high reflectivity data pits and a low reflectivity surrounding field.

Claim 25

The optical data retrieval system of claim 18 wherein light of the first and second wavelengths impinge on the same pits on the medium simultaneously.

Claim 26

The optical data retrieval system of claim 18 wherein light of the first and second wavelengths alternately impinge on the same pits on the medium.

Claim 27

The optical data retrieval system of claim 18 wherein said detector means comprises separate detectors for each wavelength.

Claim 28

The optical data retrieval system of claim 18 wherein said detector means comprises a common detector for both wavelengths.

Claim 29

The optical data retrieval system of claim 18 wherein said optical data medium is a data card having a transparent substrate and carrying a reflective recording area in which lower reflectivity data pits have been prerecorded.