Scanning device including an objective system formed of a single material
AssigneeKoninklijke Philips Electronics N.V.
InventorsBernardus Hendrikus Wilhelmus Hendriks, Pascal Jean Henri Bloemen
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Abstract
An optical scanning device (1) for scanning an information layer (4) of an optical record carrier (2), the device (1) comprising a radiation source (11) for generating a radiation beam (12, 15, 20) and an objective system (18) for converging the radiation beam on the information layer, the information layer being covered by a transparent layer (3) of thickness td and refractive index nd. The objective system comprises a lens formed of a single material. The lens satisfies the condition: Fomula (I), where t is the thickness of the lens, FWD is the free working distance between the lens (18) and the carrier (2), where t, td and FWD are expressed in millimeters, and where FWD+td/nd<0.51.
Claims15
An optical scanning device for scanning an information layer of an optical record carrier, the device comprising a radiation source for generating a radiation beam and an objective system for converging the radiation beam on the information layer, the information layer being covered by a transparent layer of thickness td and refractive index nd, the objective system being characterised in comprising a lens formed of a single material, the lens satisfying the condition:
- 0.8
- <
- t
- 1.18
- -
- 2.28
-
- [
- FWD
- +
- t
- d
- n
- d
- ]
- <
- 1.2
- where t is the thickness of the lens, FWD is the free working distance between the lens and the carrier, where t, td and FWD are expressed in millimeters, and where FWD+td/nd<0.51.
A lens system comprising at least one lens for converging a radiation beam on an information layer of an optical record carrier, the information layer being covered by a transparent layer of thickness td and refractive index nd, the lens system being characterised in comprising a lens formed of a single material, the lens satisfying the condition:
- 0.8
- <
- t
- 1.18
- -
- 2.28
-
- [
- FWD
- +
- t
- d
- n
- d
- ]
- <
- 1.2
- where t is the thickness of the lens, FWD is the free working distance between the lens and the carrier, where t, td and FWD are expressed in millimeters, and where FWD+td/nd<0.51.
A method for manufacturing a lens system comprising at least one lens for converging a radiation beam on an information layer of an optical record carrier, the information layer being covered by a transparent layer of thickness td and refractive index nd, the method comprising the step of:
- forming a lens of a single material, the lens satisfying the condition:
- 0.8
- <
- t
- 1.18
-
- –2
-
- .28
-
- [
- FWD
- +
- t
- d
- n
- d
- ]
- <
- 1.2
- where t is the thickness of the lens, FWD is the free working distance between the lens and the carrier, where t, td and FWD are expressed in millimeters, and where FWD+td/nd<0.51.
A method of manufacturing an optical scanning device for scanning an information layer of an optical record carrier, the information layer being covered by a transparent layer of thickness td and refractive index nd, the method comprising the steps of:
- providing a radiation source for generating a radiation beam;
- providing a lens system for converging the radiation beam on the information layer, the lens system being characterised in comprising a lens formed of a single material, the lens satisfying the condition:
- 0.8
- <
- t
- 1.18
-
- –2
-
- .28
-
- [
- FWD
- +
- t
- d
- n
- d
- ]
- <
- 1.2
- where t is the thickness of the lens, FWD is the free working distance between the lens and the carrier, where t, td and FWD are expressed in millimeters, and where FWD+td/nd<0.51.
Dependencies are inferred from the claim text.