摘要:
A switchable optical element having an optical path (OP) for a radiation beam and having a first state and a second state, the element comprising: a first fluid (12) and a second, different, fluid (14) which are immiscible and which are separated from each other by a fluid meniscus (16); a first, transparent, wall part and a second, transparent, wall part spaced from each other along the optical path; and a fluid switching system which is arranged to apply forces to the first and/or the second fluid in order to switch the element between the first and the second state. The first wall part includes a non-planar wavefront modifier (28), and wherein the fluid switching system is arranged to apply the forces so that when the element is in the first state, the first wall part is covered by the first fluid (12); and when the element is in the second state, the first wall part is covered by the second fluid (14). The switchable optical element is characterised in that the fluid switching system is arranged to switch between the first state and the second state such that when the element is in the first state the second wall part is covered by the second fluid, and when the element is in the second state the second wall part is covered by the first fluid. When the element is in both the first state and the second state, at least part of the fluid meniscus (16) is located on the optical path.
摘要:
An optical scanning device scans optical record carriers, such as three optical record carriers, where each optical record carrier has an information layer having a depth which is different from the information layer depth of other optical record carriers, where d3
摘要:
An optical scanning device for scanning optical record carriers having cover layers of different thicknesses. The scanning device has a first mode for scanning a first optical record carrier, a second mode for scanning a second optical record carrier and a third mode for scanning third optical record carrier. The device comprises an objective lens system and a switchable optical element having a first discrete state and a different, second discrete state. The element comprises: a fluid system including a first fluid and a different, second fluid (19); a wavefront modifier (17); and a fluid system switch for acting on the fluid system to switch between the first and second discrete states of the element. When the element is in the first discrete state, the wavefront modifier (17) is substantially covered by the first fluid, and when the element is in the second discrete state, the wavefront modifier (17) is substantially covered by the second fluid (19). The wavefront modifier includes a non-periodic phase structure including a plurality of stepped annular zones separated by steps, the zones forming a non-periodic radial pattern, and is characterized in that the wavefront modifier further includes an aspherical surface. The scanning device is arranged to operate using the element in the second state to generate spherical aberration when in the second mode, the aspherical surface of the element in the second state compensating for more than half of the spherical aberration due to the objective lens system and second record carrier in combination.
摘要:
An optical compensator is included in an optical scanning device for scanning optical record carriers. There are at least two different information layer depths within two different carriers. The scanning device produces first to third radiation beams respectively having different wavelengths for scanning first to third record carriers, respectively. The optical compensator has a non-periodic phase structure through which each radiation beam is arranged to pass. The non-periodic phase structure includes stepped annular zones separated by steps. The zones form a non-periodic radial pattern. The stepped annular zones introduce first to third different wavefront modifications into at least part of the first to third radiation beams, respectively. Radial height variations are included in the stepped annular zones, and are arranged such that non-zero contributions are provided to each wavefront modification by the optical compensator in each stepped annular zone.
摘要:
An optical compensator for use in an optical scanning device for scanning optical record carriers, there being at least two different information layer depths within two different ones of the carriers, the optical record carriers including a first optical record carrier (3′), a second optical record carrier and a third optical record carrier, the scanning device including a radiation source system (7) for producing first, second and third radiation beams for scanning the first, second and third record carriers, respectively, the first, second and third radiation beams having different predetermined wavelengths. The optical compensator has a non-periodic phase structure through which each of the first, second and third radiation beams are arranged to pass, the non-periodic phase structure including a plurality of stepped annular zones separated by steps, the zones forming a non-periodic radial pattern, the stepped annular zones introducing first, second and third different wavefront modifications into at least part of the first, second and third radiation beams, respectively. The optical compensator includes radial height variations in the plurality of stepped annular zones, the radial height variations being arranged such that non-zero contributions are provided to each of the first, second and third wavefront modifications by the optical compensator in each of the stepped annular zones.
摘要:
An optical compensator for use in an optical scanning device for scanning a first optical record carrier (3′) having an information layer (2′) at a first information layer depth d and a second optical record carrier (3″) having an information layer (2″) at a second, different information layer depth d2. The scanning of the first and second optical record carrier is effected using a scanning spot (16) formed on the information layer by a first radiation beam having a first wavelength and a second radiation beam having a second, different wavelength respectively. The optical compensator includes a substantially circular phase structure having an annular zone arranged in the path of the first radiation beam and the second radiation beam. The annular zone is adapted for imparting a wavefront modification to said first radiation beam causing destructive interference over the area of the scanning spot (16) for radiation incident on said annular zone; and a wavefront modification to said second radiation beam for compensating spherical aberration. A further aspect of the present invention relates to an optical element for defining the numerical aperture of a radiation beam. The optical compensator or optical element can be used for a two- or three-wavelength system. The invention also discloses an optical scanning head, and an optical scanning device using the optical compensator. The invention also relates to an optical scanning head and an optical scanning device.
摘要:
An optical scanning device for scanning optical record carriers, the optical record carriers including a first optical record carrier, a second optical record carrier and a third optical record carrier, the scanning device including a radiation source system (7) for producing first, second and third radiation beams for scanning said first, second and third record carriers, respectively, in first, second and third scanning modes, said first, second and third radiation beams having different predetermined wavelengths, the scanning device comprising an objective lens and an optical compensator, the optical compensator having a non-periodic phase structure through which each of said first, second and third radiation beams are arranged to pass, said non-periodic phase structure including a plurality of stepped annular zones separated by steps, the zones forming a non-periodic radial pattern, the stepped annular zones introducing first, second and third different wavefront modifications into at least part of the first, second and third radiation beams, respectively, characterized in that said objective lens is arranged to apply a focus offset when scanning said first record carrier, which focus offset is arranged to provide a phase modification which, in combination with said optical compensator, compensates spherical aberration in the first radiation beam.
摘要:
An optical wavefront modifier (27) is adapted for modifying a wavefront of an optical beam passing through the modifier. The modifier comprises a first and a second transparent electrode layer (42′, 43′) and a flat medium (46) for modifying the wavefront in dependence on electrical excitation and arranged between the electrode layers. The first electrode layer (42′) comprises three or more electrodes (51-55) of a transparent, conductive material. The electrode layer also comprises a series arrangement of resistors, comprising three terminals (48, 48′, 48″) connected to the electrodes and resistors (49, 49′) connecting the terminals. The resistors are made of the same transparent conductive material as the electrodes.
摘要:
An optical head scans the information layer (3) of an optical record carrier (1) by means of a radiation beam (13). Optical aberrations in the beam such as coma and spherical aberration, caused by tilt and thickness variations in the optical disc respectively, are compensated by an aberration compensator (27) arranged in the radiation beam. The tilt or thickness variation is measured by a detector (30) and used to control the aberration compensator. The radiation beam is focused onto the information layer by an objective system (11). A displacement of the objective system in the transverse direction (26) as used for radial tracking of the optical beam, causes a mismatch between the wavefront to be compensated and the wavefront introduced by the aberration compensator (27). The mismatch is reduced by using a position detector (33) for measuring the transverse position of the objective system and using the position signal (34) as input for the control of the aberration compensator.
摘要:
The invention relates to an optical scanning device for scanning in a first mode a first information layer (111) of an information carrier and in a second mode a second information layer (112) of the information carrier. The optical scanning device comprises a radiation source (101) for generating a radiation beam (102), an objective system (105) for focusing an entrance beam on an information layer and an optical element (103) arranged between the radiation source and the objective system, for converting said radiation beam into a diverging entrance beam in the first mode and a converging entrance beam in the second mode.