Abstract: A surface plasmon sensor comprises a prism, a metal film, which is formed on one surface of the prism and is brought into contact with a sample, and a light source for producing a light beam. An optical system causes the light beam to pass through the prism and to impinge upon an interface between the prism and the metal film such that various different angles of incidence may be obtained with respect to the interface. A photodetector detects an intensity of the light beam, which has been totally reflected from the interface, with respect to each of the various different angles of incidence. An electrode stands facing the metal film with a liquid sample intervening therebetween, and a DC voltage is applied across the electrode and the metal film. A substance contained in the liquid sample is thus analyzed quickly and with a high sensitivity.

Abstract: A device is described for aligning a first object provided with a first alignment mark (P) with respect to a second object provided with a second alignment mark (M), which marks have a periodical structure and are imaged onto each other. By selecting beam portions from the radiation from the first alignment mark (P) with the aid of an order diaphragm (55'), which beam portions are deflected through larger angles, the sensitivity of the device to errors can be decreased. Such a device may be used to great advantage in a lithographic apparatus.

Abstract: A fluorescence sensing device for determining the presence or concentration of an analyte in a liquid or gaseous medium is constructed of a fiber optic plate comprising optical fibers having relatively small numerical apertures. The fiber optic plate is positioned on a photodetector and has a layer of analyte permeable fluorescent matrix or coated waveguide material on its top surface. The fluorescent matrix or waveguide coating contains indicator molecules whose fluorescence is affected by the local presence of analyte. A light source emits light into the fluorescent matrix in a direction generally parallel to the top surface of the fiber optic plate. Upon absorbing light from the light source, indicator molecules in the fluorescent matrix emit fluorescent light which is transmitted through the fiber optic plate to the photodetector.

Abstract: In a method of determining concentrations by means of atomic absorption spectrometry, the absorption of structured background is determined in a graphite furnace.

Abstract: A mirror includes a mirror body with a reflective coating on at least one mirror surface. The mirror body is formed of a plastic into which a filler is mixed. The mirror body is preferably formed by injection molding of a mixture of the plastic and the solid filler. The mirror is used in optical imaging applications such as an infrared optical system.

Abstract: An illuminance measuring method and apparatus measures the illuminance on a wafer in an exposure apparatus for projecting a pattern formed on a mask onto a wafer. The illuminance of the mask causes the formation of ghost light on the mask. The apparatus and method use a first technique to measure the illuminance on the wafer while a mask used for actual exposure is mounted in the exposure apparatus and the mask is illuminated. The apparatus and method also use a second technique, different form the first technique, to measure the illuminance on the wafer while the mask used for actual exposure is mounted in the exposure apparatus and the mask is illuminated. The apparatus and method also find the distribution of the ghost light caused by the mask, based on the illuminance measured by these two techniques.

Abstract: An optical imaging system provides automatic co-registration of a plurality of multi spectral images of an object which are generated by a plurality of video cameras or other optical detectors. The imaging system includes a modular assembly of beam splitters, lens tubes, camera lenses and wavelength selective filters which facilitate easy reconfiguration and adjustment of the system for various applications. A primary lens assembly generates a real image of an object to be imaged on a reticle which is positioned at a fixed length from a beam splitter assembly. The beam splitter assembly separates a collimated image beam received from the reticle into multiple image beams, each of which is projected onto a corresponding one of a plurality of video cameras. The lens tubes which connect the beam splitter assembly to the cameras are adjustable in length to provide automatic co-registration of the images generated by each camera.

Abstract: A laser Doppler encoder includes a set of prisms mounted on a fixed base along with an additional prism, an end retroreflector and a laser/detector and a second set of prisms mounted on a moving/rotating base. The laser/detector generates a laser beam that is transmitted through the sets of prisms on the fixed and moving bases as well as the additional prism and the end retroreflector until the laser beam finally reaches a heterodyning detector that is housed coaxially inside the laser/detector. The laser beam is a frequency-stabilized laser beam such that the laser beam that is reflected back to the heterodyning detector is frequency-shifted by the movement of the moving base relative to the fixed base so that the amount of movement (either rotational or linear) of the moving base can be accurately determined.

Abstract: A colorimeter method and apparatus is described that is used to accurately deduce the color of a source which is varying in intensity with respect to time. The colorimeter consists of a plurality of sensors with varied spectral responsivity, a means of shielding these sensors from the effects of ambient illumination and a computational element to analyze the temporal and intensity variation of the signal under measurement. The output from the sensors is integrated and analyzed based upon the measured light intensity, time variant, and characteristics of the source. Sources such as CRT monitors, Flat Panel displays, and stroboscopic illuminators, are typical representations of time variant sources.

Abstract: A system for sampling and analyzing a material located at a hazardous site. A laser located remote from the hazardous site is connected to an optical fiber, which directs laser radiation proximate the material at the hazardous site. The laser radiation abates a sample of the material. An inductively coupled plasma is located remotely from the material. An aerosol transport system carries the ablated particles to a plasma, where they are dissociated, atomized and excited to provide characteristic optical reduction of the elemental constituents of the sample. An optical spectrometer is located remotely from the site. A second optical fiber is connected to the optical spectrometer at one end and the plasma source at the other end to carry the optical radiation from the plasma source to the spectrometer.

Abstract: A device used to align the rear end of a vehicle that can be mounted on the axle of the vehicle and that generates a linear laser beam that is perpendicular to the axis of the axle so that measurements can be made between the beam and the frame of the vehicle to assist in properly aligning the rear end of the vehicle relative to the frame.

Abstract: Described is a device (16) for the selection and detection of at least two spectral regions in a beam of light (14), the device including a selection unit (25) and a detection unit (26). To ensure reliable simultaneous selection and detection of different spectral regions plus high yield and simplest possible construction, the device is designed such that the selection unit (25) comprises means (27) for splitting the light beam (14) up into its spectral components and means (28) for not only masking off a first spectral region (29) but also reflecting at least part (30) of the spectral region which is not masked off, and the detection unit (26) comprises a first detector (31) located in the path of the light in the masked-off first spectral region (29) and a second detector (32) located in the path of the light of the reflected spectral region (30).

Abstract: A high sensitivity and high throughput surface inspection system directs a focused beam of light at a grazing angle towards the surface to be inspected. Relative motion is caused between the beam and the surface so that the beam scans a scan path covering substantially the entire surface and light scattered along the path is collected for detecting anamolies. The scan path comprises a plurality of arrays of straight scan path segments. The focused beam of light illuminates an area of the surface between 5-15 microns in width and this system is capable of inspecting in excess of about 40 wafers per hour for 150 millimeter diameter wafers (6-inch wafers), in excess of about 20 wafers per hour for 200 millimeter diameter wafers (8-inch wafers) and in excess of about 10 wafers per hour for 300 millimeter diameter wafers (12-inch wafers).

Abstract: A robust spectrophotometer (also known as a color spectrometer or colorimeter) is self contained in a housing which is adapted to be held-held and has all of the electrical, optical and electro optic elements mounted on a board captured within the housing at one end of which light from a sample is restricted to an object area and projected after being dispersed spectrally, as with a reflection grating, to an image area at a photodetector via a lens which has an optical axis and converges the dispersed light at the image area. The dispersive element is mounted on an arm having a pivot laterally offset from the dispersive element's surface where a diverging beam of light from the object area is incident and is deflected to the image area. The geometry is such that the dispersive element may be rotated to a position where the beam is specularly deflected (zeroth order diffraction), and the spectrometer calibrated when the dispersive element is in the specular reflection/deflection position.

Abstract: The invention relates to an apparatus and method for measuring visibility and present weather. The apparatus includes a light source (1) for directing a light ray toward the object (9) to be measured, a detector (3) for measurement of light which is forward scattered from the object (9), and computing elements (12-15) adapted to differentiate the signal representing the forward scattered light from signals representing stray or ambient light. The apparatus may include a pulsed light source, a receiver (19) for receiving directly backward reflected/scattered light pulses, and computing elements (11) for computing the propagation delays of the different backward reflected components in the received pulse-shaped optical signal.

Abstract: A method for overlay metrology and control. Simultaneous use of between-field overlay metrology to control field term alignment error at all levels and level-to-level metrology to control field term, grid term, and translation alignment errors at all levels is applied.

Abstract: In an apparatus scanning an alignment mark formed on a silicon substrate by an electron beam to determine the center position of the alignment mark based on the reflected signal waveform, a proportional relationship holds between a beam size which is the thickness of the electron beam and the amount of offset between the detected mark position and the actual mark position. More specifically, when the beam size is small, the amount of offset of the detected position from the actual position is small. In the mark position determining apparatus according to the present invention, the alignment mark is detected a plurality of times by the electron beams having a plurality of sizes, and based on the mark detection positions obtained by the respective detections, the mark detection position when scanning is carried out by an electron beam having a beam size of 0 is calculated.

Abstract: A readhead for a photometric diagnostic instrument for illuminating a target area substantially uniformly via only a single light-emitting diode (20) and receiving light from the target area so that reagent tests may be performed is provided with a housing (12, 14, 16) adapted to be incorporated in a photometric diagnostic instrument, first and second light sources (20) mounted in a fixed position relative to the housing (12, 14, 16), a light guide (26) mounted to receive light from each of the light sources (20) which conveys, when only one of the light sources (20) is illuminated, substantially all of the light from the light source (20) to illuminate a target area substantially uniformly, and a light detector (70) coupled to receive light from the target area. Each of the first and second light sources (20) is composed of only a single light-emitting diode (20) for emitting substantially monochromatic light of a different wavelength.

Abstract: A method of measuring the radius of curvature of the convex tip of a core protruding from the end of an optical transmission path is disclosed. The transmission path is implemented by an optical fiber. A measuring unit accommodating a condenser and an infrared camera is located to face the convex tip of the core. A semiconductor laser is connected to the end of the fiber remote from the convex tip. A laser beam issuing from the convex tip of the core is once condensed by the convex tip. The measuring unit determines the condensing point of the beam, and then measures the distance between the condensing point and the convex tip. Subsequently, after the space between the convex tip and the condenser has been filled with a medium different in refractive index from air, the measuring unit again measures the above distance. The radius of curvature of the convex tip is determined on the basis of a difference or a radio between the measured distances.

Abstract: An azimuth alignment system for an underground azimuth alignable device, the azimuth alignment system including (a) an underground unit including two spaced linear light sensitive articles on an upper face thereof, each of the light sensitive articles including a row of miniature light sensitive elements, the underground unit being connectable in a known positional relation to the underground azimuth alignable device; and (b) an aboveground azimuth alignable telescope device having a longitudinal axis, the telescope device including an aboveground unit, the aboveground unit including at least one light source for generating at least one light beam being detectable by the miniature light sensitive elements of the light sensitive articles, each of the light sources being positioned in a known relation with respect to the longitudinal axis of the telescope device, such that by aligning the telescope device in a desired azimuth and illuminating the light sensitive articles of the underground unit, a deviation of