Abstract: The present invention relates to an optical scanning device for reading and/or writing on a plurality of tracks on an optical storage medium (1), said scanning device comprising optical means (17) for focusing a plurality of beams, after being reflected from said medium, onto an observation plane (22), and for introducing astigmatism into at least one of said reflected beams, and a photo-detector (18) comprising a plurality of detector segments, arranged in said observation plane (22) to receive said at least one astigmatic reflected beam.

Abstract: A method for controlling an optical disc drive apparatus (1) which comprises: light beam generating means (31) for generating a plurality of N optical beams (32(i)); means (33, 34, 37) for focusing said beams in respective focus spots (F(i)); at least one adjustable member (34) for axially displacing said focus spots; comprises the step of calculating an optimum setting (ZOPTIMUM) for the adjustable member (34), such that the out-of-focus condition for the optical system (30) as a whole is as small as possible. The position of the adjustable member (34) may be controlled to be substantially equal to the said optimum setting (ZOPTIMUM). Or, one specific beam is maintained in a focus condition, the beam having number m=mOPT selected according to mOPT=±INTEGERSQUARE{(N?1)/(2?2)} in case N is odd or mOPT=±INTEGERROUND IN?(N?2)/8) in case N is even.

Abstract: An optical scanning device for scanning optical record carriers having information layers at different information layer depths within the carrier, the optical record carriers including a first optical record carrier (3?) having an information layer (2?) at a first information layer depth d1, a second optical record carrier (3?) having an information layer (2?) at a second information layer depth d2 and a third optical record carrier (3??) having an information layer (2??) at a third information layer depth d3, wherein d3<d2<d1. The scanning device includes a radiation source system (7) for producing first, second and third radiation beams (4?; 4?; 4??), for scanning said first, second and third record carriers (3?; 3?; 3??), respectively, the device including a diffraction structure (48) introducing first, second and third, different, wavefront modifications into at least part of the first, second and third, radiation beams, respectively.

Abstract: Apparatus and method for measuring the depth of data record layers of an optical storage disc having a cover layer of thickness d, an entrance surface (S), and, for example, a first data layer (L0), a second data layer (L1) and a third data layer (L2). The optical apparatus comprises a spherical aberration compensator (SA), and an objective lens (OL) mounted in an actuator (AC), the actuator (AC) receiving a current I and being arranged and configured to move the objective lens (OL) in the z (axial) axis relative to the optical storage disc. Light incident on the objective lens (OL) is converged into a cone-like beam such that it is focussed on one of the data layers (D1). A control signal is used to keep the scanning spot focussed on the data layer (L1). This control signal is the focus error signal (FES) and is provided by the actuator drive (AC).

Abstract: The present invention enables to determine the property of a fluid, such as for the purposes of in vivo blood analysis. First the position of a volume of interest through which the fluid flows is determined by means of an optical detection step by making use of an objective. Preferably the optical detection step is an imaging step. Next the objective is moved to bring the focal point of the objective to the volume of interest. In this position an optical spectroscopic step is performed. This has the advantage that the measurement beam for performing the optical spectroscopy travels along the optical axis for optimum efficiency.

Abstract: An optical system includes a light source that outputs light that is incident on an oscillating reflector. The optical system includes at least one lens element, which outputs the light in a collimated beam on the oscillating reflector regardless of an orientation of the oscillating reflector. The optical system may be used in laser displays in general, and in small feature laser displays.

Abstract: A beam-shaping element comprises a cavity, a first: fluid and a second fluid having different indices of refraction. An optical axis extends through the cavity. The cavity has at least one curved surface extending transverse the optical axis. At least one pump is arranged to pump the fluids between a first configuration in which the first fluid occupies the cavity, and a second configuration in which the second fluid occupies the cavity.

Abstract: A optical scanning device (1) for scanning an information layer (2) with a radiation beam (25) in a writing mode and a reading mode comprises a radiation source (7) for emitting the beam and an objective lens (10) for converging the beam so as to form a scanning spot (19) in the information layer. The device also includes a scanning spot power switch (20) for switching the size of the cross-section of the beam between a first size at the writing mode and a second, larger size at the reading mode so as to switch the rim intensity of the beam between a first intensity level (Irim,writing) at the writing mode and a second, higher intensity level (Irim,reading) at the reading mode, thereby switching the light power of the scanning spot between a first power level (Pwriting) at the writing mode and a second, lower power level (Preading) at the reading mode.

Abstract: An optical head for use in the scanning of a record carrier, the record carrier having data stored on data tracks therein on a plurality of information layers (3, 4) at a plurality of depths within the record carrier. The optical head comprises: a movable optical element (16) arranged in an optical path to act upon a first radiation beam (12) and a second radiation beam (14) to provide the beams with a different displacement perpendicular to the optical path; and a lens system for focusing said first beam (12) at a first focal point (A) on a first information layer (3) of the record carrier and the focusing of the second beam (14) at a second different focal point (B) on a second information layer (4), wherein a spacing, transverse to the data tracks, between said first and second focal points (A, B) is controllable by varying the configuration of the movable optical element.

Abstract: An optical scanning device (1) is for scanning an information layer (2) by means of a radiation beam (4). The device includes a radiation source (7) for supplying said radiation beam, an objective lens (10) for transforming said radiation beam into a scanning spot (19) at the position of the information layer, and a beam intensity modifier (8) for redistributing the intensity (I2) over the cross-section of said radiation beam in order to change the size of said scanning spot. The beam intensity modifier has an entrance pupil (8a) and an exit pupil (8b). Furthermore, it is arranged so that any ray of said radiation beam entering said beam intensity modifier at a distance r1 from the central ray of that beam reflects at least twice between said entrance and exit pupils that the transverse magnification M of said modifier is defined by a decreasing function of the distance r1.

Abstract: The invention relates to an objective lens and an optical device for scanning different information carriers having different cover layer thicknesses, with different numerical apertures. The objective lens (10, 20) comprises at least an annular part (101, 201) having a first numerical aperture and a central part (102, 203) having a second numerical aperture. The second numerical aperture is higher than the first numerical aperture.

Abstract: An optical scanning device 1 detects an information signal from an optical record carrier 2 using differential interference contrast. Two radiation beams 13a, 13b are generated and focused to two distinct spots 15a, 15b respectively displaced along a data track on the information layer of an optical record carrier. The relative positions of the spots in lands and pits can generate a path length difference between the reflected beams 17a, 17b. This path length difference causes the beams to interfere either constructively or destructively, depending on the relative land/pit position in the data track of the spots. This interference causes a detectable signal to be generated, the signal being representative of a transition from a pit to a land on the information layer 4 or vice versa.

Abstract: This invention relates to an optical scanning device for scanning an optical record carrier and detecting a tilt characteristic of the optical record carrier during scanning. The device includes a redirecting structure (26) arranged on an objective lens (10) to redirect a part of a radiation beam, when travelling towards the record carrier, differently to a main part of the radiation beam. The redirected beam part follows a path which is different to that of a path followed by the main beam part, towards a position sensitive detector in a detection system (16).

Abstract: An optical scanning device (1) for scanning an information layer (4) of an optical record carrier (2), the device including a radiation source (11) for generating a radiation beam (12) and an objective system (18) for converging the radiation beam (12) on the information layer, the objective system (18) being characterized in that the ratio of the root mean square of the optical path difference's (OPD's) generated by the objective system at oblique beam entrance to the system satisfies the condition of formula (I) within the field of the objective system, where OPD(A31) is the contribution of the third order Zernike coma to the root mean square wavefront aberration and OPD(A51) is the contribution of the fifth order Zernike coma to the root mean square wavefront aberration.

Abstract: A dual-stack optical data storage medium (20) is described for read out using a focused radiation beam (29) with a wavelength of 400-410 nm and a Numerical Aperture (NA) of 0.84-0.86. The medium has a substrate (21) and a first stack of layers named L0 (22) comprising a first information layer and a second stack of layers named L1 (23), comprising a second information layer. A radiation beam (29) transparent spacer layer (24) is present between L0 and L1. A transmission stack named TS0 with a thickness dTS0 and an effective refractive index nTS0 contains all layers between L0 and an entrance face (26) of the medium (20). A transmission stack named TS1 with a thickness dTS1 and an effective refractive index nTS1 containing all layers between L1 and the entrance face (26). The spacer layer (24) has a thickness selected from the range 20-30 ?m, the thickness dTS0 in dependence on the refractive index nTS0 and the thickness dTS1 in dependence on the refractive index nTS0 are within a specified area.

Abstract: An optical scanning device is for scanning an information layer (2) with a radiation beam (4). It includes: a radiation source (6) for providing said radiation beam, a lens system (7) for transforming said radiation beam to a scanning spot (17) on said information layer, and a wavefront modifier arranged between said radiation source and said scanning spot. The modifier including two elements (301, 302) having each an aspheric surface (301b, 302a) and being mutually linearly movable for introducing a wave-front modification in said second radiation beam. According to the invention, the aspheric surfaces are shaped so that: a first mutual linear displacement of the elements (301, 302) introduces a first wavefront modification (Wa) along a first axis (XO) in said second radiation beam, and a second mutual linear displacement of the elements introduces a second wavefront modification (Wb) along said second axis (YO) in said second radiation beam.

Abstract: An optical head (1) for scanning an optical record carrier (2) is provided with a compensator (16) for compensating the field curvature aberration of the objective system (18) caused by operation of the optical head at a different field angles. A surface of the compensator (16) comprises a phase structure in the form of annular areas (52, 53, 54, 55, 56), the areas forming a non-periodic pattern of optical paths of different lengths. The optical paths change as a function of field angle and form a field angle-dependent wavefront deviation that compensates field curvature of the optical head.