U.S. Philips Corporation

Josephus J Braat

Willem G Opheij

Gijsbertus Bouwhuis

Albert Smid

Jan Haisma

Petrus Theodorus Jutte

Willem Gerard Ophey

Marino G Carasso

Bernardus A Jacobs

Peter Ferdinand Greve

Kornelis A Immink

James H Coombs

Joannes Gregorius Bremer

Gijsbert Prast

Gerardus J Vos

Jacobus P Kroon

Johannes J Baalbergen

Alexius J Van Sambeeck

Jacob Sonneveld

Igolt P Ubbens

Johannes W Bosch

An optical beam shaper (10) for converting a radiation beam (5, 6, 7, 8) having an elliptical cross-section into a beam (9) having a more circular cross-section is described. This element (10) has a cylindrical entrance surface (12) and a toroidal exit surface (14) and can be arranged close to a diode laser (1) so that the risk of wavefront deviations due to defocusing is reduced. The element has a high coupling efficiency. The beam shaper is also provided with a grating for forming a sub-beam from the radiation beam.

Optical beam shaper, and radiation source unit and scanning device

A projection system is described for projecting a mask pattern on a substrate by means of EUV radiation, which projection system consecutively comprises a first concave mirror (1), a convex mirror (2) and a second concave mirror (3). Since the system has a focal length f which is at least equal to +1/2 L, in which L is the length of the system, and the chief ray of the object beam (b.sub.2) leaving the object plane (V) is inclined towards the optical axis (OO'), a compact system is obtained whose first concave mirror (1) has relatively moderate dimensions and in which the axial positions of the concave mirrors (1, 3) are approximately equal, so that these mirrors can be arranged on a common support.

Three-mirror system for lithographic projection, and projection

A device for optically scanning a record carrier with radiation beam having a high numerical aperture. The radiation beam is focused on the record carrier by an objective lens and a plano-convex lens. The plano-convex lens has a gap with the record carrier of several tens of micorometers. It focuses the radiation beam to a point at least 30 focal depths away from an aplanatic point of the plano-convex lens. As a consequence, the lens has a relatively large tolerance for sideways movements.

Focusing more than 30 depths from an aplanatic point of a plano-convex

A scanning device for optical record carriers is provided with an objective lens (7) suitable for scanning record carriers (1, 21) having a transparent substrate (2, 23) of different thicknesses. The lens comprises an outer annular part (25) and an inner central part (26) within the annular part. Only the central part of the lens is used for forming a focus through a first substrate (2) having a first thickness. The central part is corrected for the spherical aberration of the first substrate. The annular and central part of the lens are used for forming a focus through a second substrate (23) having a different, second thickness. The annular part is corrected for the spherical aberration of the second substrate.

Objective lens and scanning device using such an objective lens

Imaging conditions for the aperture rays of an axial pencil, for example Abbe's sine condition, determine how an object volume will be imaged in the image space of an optical lens system. The invention provides an optical lens element having an imaging condition which analytically should lead to the largest possible volume in an image space wherein possible aberrations (spherical aberration and coma) remain below a certain prescribed level.

Optical imaging system

An optical scanning device can scan two types of record carriers each having a transparent layer with a different thickness, in which a focused radiation beam scans an information layer of the record carrier through the transparent layer. When scanning a first type of record carrier the best focus of the radiation beam is positioned on the information layer and when scanning a second type of record carrier the paraxial focus of the radiation beam is positioned on the information layer. The lens system focusing the radiation beam comprises an opaque ring between a transparent central area and a transparent annular area.

Device for optically scanning record carriers of different thicknesses

A device for optically scanning an information layer by means of a focused radiation beam. Radiation reflected from the information layer is made astigmatic by an oblique plane parallel plate and subsequently detected by a detection system. An electronic circuit derives two focus error signals, each representing the distance between the focal point of the radiation beam and the information plane. The first focus error signal is formed from the high-frequency components in the electrical detector signals, and the second focus error signal is formed from the low-frequency components in the same detector signals. A second electronic circuit combines the two focus error signals into a combined focus error signal to control a focus servo loop. The circuit changes the control gradually from one focus error signal to the other.

Device for scanning an optically readable record carrier

A device for optically scanning an information layer by means of a focused radiation beam. Radiation reflected from the information layer is made astigmatic by an oblique plane parallel plate and subsequently detected by a detection system. An electronic circuit derives a focus error signal, representing the distance between the focal point of the radiation beam and the information plane, from the electrical detector signals by using the high-frequency components in the detector signals. The influence of stray light falling on the detection system on the focus error signal is thereby reduced.

A device for optically scanning an information layer by means of a focused radiation beam. Radiation reflected from the information layer is made astigmatic by an oblique plane parallel plate and subsequently detected by a detection system. An electronic circuit 26 derives two focus error signals, each representing the distance between the focal point of the radiation beam and the information plane. The first focus error signal is formed from the high-frequency components in the electrical detector signals, and the second focus error signal is formed from the low-frequency components in the same detector signals. A second electronic circuit combines the two focus error signals to a combined focus error signal.

Apparatus for scanning an optically readable record carrier

An imaging system with at least one reflective surface for forming an image by means of ultraviolet radiation, the reflective surface being provided with a correction layer which is transparent to the wavelength of the radiation used. This layer compensates for phase differences caused by deviations of form of the reflective surfaces. The correction layer has a refractive index which differs only slightly from 1, so that the requirements imposed as regards the precision of the surface of the transparent layer are significantly less severe than for the reflective layer.

Imaging system and apparatus for ultraviolet lithography

A wide angle objective system is described for, inter alia CCD cameras, which system is compact, inexpensive and satisfactorily corrected. It comprises a front meniscus lens (L.sub.1), a thick convex-concave central lens element (L.sub.2) and a biconvex lens element (L.sub.3), the two last-mentioned elements preferably being cemented together, the pupil (P) being present at the area of the exit surface (4) of the second lens element and the first and the third element (L.sub.1,L.sub.3) being made of, for example PMMA and the second element (L.sub.2) being made of, for example PC.

Wide angle objective system

A record carrier having standard and high-density information layers. The standard density layer, e.g. in a standard CD format, is positioned at the bottom of a substrate, and is read out through the substrate with a laser beam. The thickness of the substrate is within the CD specification, e.g. 1.2 mm. At least one high-density layer is formed by a material which is (nearly) transparent for the laser wavelength of standard CD players (.lambda.=780 nm), but is (at least partially) reflective for shorter wavelengths used for high-density discs (.lambda.=635 nm). To achieve a high density, a smaller track pitch and smaller pits are used in the high-density layer(s). To achieve better reading signals from both layers, the high-density layer is positioned closer to the side of entrance of the laser beam in the substrate. A higher numeric aperture of the focusing lens and, therefore, a smaller spot for the shorter wavelength results. The high-density layer is preferably positioned midway in the substrate, e.g. at 0.6 mm. Such high-density layer configuration is compatible with two-sided high-density discs which have a total thickness of 1.2 mm. The information content of the standard layer may be duplicated on the high-density layer, or it may be represented by a different coding scheme.

Optical information carrier including standard and high density layers

An optical scanning device can scan two types of record carriers each having a transparent layer with a different thickness, in which a radiation beam scans an information layer of the record carrier through the transparent layer. When scanning a first type of record carrier the best focus of a scanning radiation beam is positioned on the information layer and when scanning a second type of record carrier the paraxial focus of the radiation beam is positioned on the information layer.

Device for optically scanning a recording medium by focusing the best

A measuring device for determining the displacement of a movable object includes a graduation element which is mechanically connected to the object whose displacement is to be determined. The graduation element comprises at least a track which is formed by a plurality of successive grating strips located transversely to the direction of movement of the object. The measuring device also includes a radiation source, a detector and a reflective optical system which comprises at least a beam collimating element. The reflective optical system guides the radiation from the radiation source to the graduation element and changes it to an elongate radiation beam which is parallel on average in the cross-section perpendicular to the grating strips.

Measuring device for determining the displacement of a movable object

A beam-shaping element for converting a beam having an elliptical cross-section into a beam having a circular cross-section. This element has a cylindrical entrance surface and a toriodal exit surface and can be arranged close to a diode laser so that the risk of wavefront deviations due to defocusing is reduced. The element has a high coupling efficiency.

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Eindhoven, Netherlands

Josephus J Braat