Abstract: A phase fluorometer employs a baseband frequency generator to generate a sample baseband signal at a first frequency f.sub.o and a reference signal correlated to the sample baseband signal. A second signal generator generates a carrier signal having a second frequency f. The sample baseband signal and the carrier signal are combined to form an up-converted sample signal having a frequency f.+-.f.sub.o. A light source is modulated at the up-converted sample signal frequency f.+-.f.sub.o to illuminate a sample. A photo detector detects fluorescence emissions from a sample excited by the excitation light and converts the emission into a fluorescence signal. A down-converter combines the carrier signal and fluorescence signal to form a phase-shifted and down-converted sample signal. A processor digitally processes the phase-shifted and demodulated sample signal and the reference signal to determine the fluorescence lifetime.

Abstract: In a method and a device for optically characterizing a goniochromatic surface, for example a metallic painting surface, only a fixed measuring angle setting is used according to the invention.

Abstract: An apparatus for carrying out laser-induced two-photon fluorescence correlation spectroscopy (TPA-FCS), in which a plurality of volumes (6) are delimited or defined in the apparatus in such a way that samples (3) introduced into these volumes can be excited and observed in parallel by means of a single laser (1). Such an apparatus is e.g. used to screen active compounds.

Abstract: A method and system are provided for measuring a two-dimensional deflection angle of a beam of light reflected from a disk having unknown radial and tangential tilt components by first generating reference data relating to known tilt of a reference disk and then processing the reference data with electrical signals from a two-dimensional photodetector to obtain values related to the deflection angle and the unknown radial and tangential tilt components. The photodetector is preferably a semiconductor photodiode having an active area which measures position of radiant energy in a spot of light focused in a detector plane by a focusing lens. A signal processor including a computer system programmed in accordance with a software algorithm compensates for interaction between X and Y axes of the active area of the photodiode to compensate for alignment errors or tolerances, not only up, down, left and right, but also for rotational errors as well.

Abstract: In an apparatus and method for measuring in-plane distribution of surface free energy, a target substrate is immersed in a liquid, and a parameter representing a state of meniscus to be formed at an intersection area of a target surface with a surface of the liquid is measured along the surface of the liquid. This measurement is performed by descending or ascending the substrate, thereby measuring the parameter throughout the entire surface of the target surface, and then, the in-plane distribution of the surface free energy of the target surface is calculated.

Abstract: A reticle pre-alignment apparatus and method are provided. The apparatus includes a reticle carrier for loading a reticle at a predetermined position on a reticle stage, a light source arranged over the reticle stage for emitting light, an alignment mark formed in the reticle for passing the light, a sensor arranged under the reticle stage for receiving the light passed through the alignment mark to generate a predetermined signal, and a controller for processing the signal from the sensor to drive the reticle carrier, thereby enhancing productivity and simplifying the pre-alignment apparatus and method by increasing speed and accuracy.

Abstract: A method and system for determining the position and/or orientation of a number of objects relative to each other. At least two cameras having electro-optical sensors are provided. A network of help reference points is established. The positions of some points in the network relative to each other can be known or they are determined using at least one of the cameras positioned in multiple arbitrary locations. The positions of some of the objects relative to each other, are determined based on the determined positions of some of the points in the network. The position of at least one of the objects is determined by holding a probing tool in contact with a point on the object, and obtaining measurement data from the probing tool using at least two of the cameras.

Abstract: A process for determining critical dimension bias or overlay error in a substrate formed by a lithographic process initially provides an array of elements on a substrate, the array comprising a plurality of spaced, substantially parallel elements having a length and a width. The sum of the width of an element and the spacing of adjacent elements define a pitch of the elements. Edges of the elements are aligned along a line forming opposite array edges, with the distance between array edges comprising the array width. An optical metrology tool used for measurement of the array is adjustable for one or more of i) wavelength of the light source, ii) numerical aperture value or iii) partial coherence.

Abstract: A method of measuring and compensating the effects of stray light in a spectrometer and use of the method to improve linearity and accuracy in the spectrometer. Light from a broadband light source (100) is blocked in a particular band of wavelengths by an optical filter (104) and light outside the particular band of wavelengths is transmitted by the filter. A spectral measurement within the particular band measures aggregate offset, including the effects of stray light, dark current and electronic offset. In absorption spectrometry, a first spectral measurement within the particular band is measured with a chemical sample not present and a second measurement is made with a chemical sample present. The first spectral measurement is used for compensation of a reference spectrum and the second spectral measurement is used for compensation of a sample spectrum, each within the particular band.

Abstract: The invention relates to methods and apparatus for precise dilution of concentrated samples enabling their spectra to be obtained. The spectra thus obtained may then be used for calculation of the aromatic hydrocarbon content in the concentrated samples. This invention comprises an arrangement of computer-controlled pumps, an injection valve, a mixing chamber, a flow cell (these components are known as "the manifold") and a scanning spectrophotometer, with a sophisticated computational software program. The arrangement generates a reproducible, well-defined gradient from a concentrated sample which is continuously scanned and, using the computational software, allows the spectrum of the sample to be derived, even where the majority of the spectrum for the undiluted sample has an absorbance greater than the upper measurable limit of the spectrophotometer.

Abstract: An optical axis of a headlight of a vehicle is adjusted by picturing an illuminating pattern of the headlight to appear on a screen which is disposed in front of the vehicle. A position of a center of gravity of a region above a predetermined illuminance in the illuminating pattern is obtained. A position of a stepped region in which a stepped portion of a light/dark border line of the illuminating pattern is present is obtained. A position of a point of inflection, in the stepped region, of an iso-illuminance curve having a predetermined rate of illuminance relative to an illuminance in the center of gravity is measured. The optical axis is adjusted based on this point of inflection.

Abstract: A detector array spectrometer simultaneously monitors wavelength, power, and signal-to-noise ratio of wavelength division multiplexed (WDM) channels in telecommunication networks. A spectrometer spatially separates signals from the WDM channels according to the channels' wavelengths. The separated signals are incident on an array of split-detectors that conforms to the spatial separation of the signals provided by the spectrometer. While the split-detectors are positioned to receive a signal from each WDM channel, a noise detector is positioned between adjacent split-detectors to measure noise. A common mode output from two halves of each split-detector indicates the power in a WDM channel, while a differential output from the halves indicates wavelength deviations in the WDM channels. The ratio of the common mode signal to the noise detector signal is used to monitor the signal-to-noise ratio of the WDM channel.

Abstract: A position detection device for detecting the position of an object includes a light source for generating light, an illumination device introducing the light from the light source to the object, and a detector for detecting the position of the object on the basis of a sensed optical image. The detection device further includes an image forming optical system for forming the image of the object on a detection surface of the detector at a first magnification. The device also includes an optical member insertable into and retractable from an optical path of the light travelling from the object to the detector. Insertion of the optical member into the optical path allows the light from the object which has been passed through at least part of the optical member and the image forming optical system to form the image of the object on the detection surface of the detector at a second magnification smaller than the first magnification.

Abstract: The present invention provides a laser beam levelling device which is provided with two rotatable heads wherein a horizontal laser plane can be emitted from the first head which is rotatable round a vertical axis and a vertical laser plane can be emitted from the second head which is rotatable round a horizontal axis. An apparatus consisting of two separate pendulums is provided for self-levelling of the two laser planes. One pendulum is mounted substantially in the lower extension of the axis of rotation of the first head. The other pendulum is arranged to the side of it in its own vertical axis. The first pendulum is pivotal about a substantially horizontal axis and the second pendulum about an axis which is also horizontal and at right angles thereto. A laser beam produced by a laser light source is guided by reflectors such that it is deflected from one pendulum to the other pendulum and from there into the rotating heads.

Abstract: A light beam emitted by a hollow cathode lamp is concentrated on a central portion of an electrothermal sample atomizing apparatus by a concave mirror. The light concentrated on the central portion of the electrothermal sample atomizing apparatus is further concentrated on a central portion of a flame produced in a burner type sample atomizing apparatus by a lens. The light traveled through the burner type sample atomizing apparatus is condensed by a concave mirror, reflected by a flat mirror, and concentrated on an entrance slit of a spectroscope. Light outgoing through an exit slit of the spectroscope is detected by a photodetector.

Abstract: An optical spectrum measuring apparatus is disclosed that is able to take measurements at high speed. An encoder is connected to the rotational axis of a motor. A counter counts the number of pulses outputted from the encoder 14. A comparator, that is connected to the counter and a register, compares a value stored in the counter with a value stored in the register set by a control section, and outputs an AD conversion signal when the values are equal. The control section sets the register with a value corresponding to a first measurement point and rotates a diffraction grating at a constant speed from an angle corresponding to a measurement initiation wavelength to an angle corresponding to a measurement termination wavelength. An AD conversion signal is outputted from the comparator when a measurement point is reached, then the control section sets the register to a value corresponding to the next measurement point.

Abstract: The present invention is a unique method for identifying the presence, and preferably the identity, of a fluorophore by optically stimulating one or more fluorophores with an optical signal which has been modulated in intensity in the time domain. The stimulated fluorophore produces a resulting fluorescence which is demodulated to produce an electrical signal corresponding to the intensity modulation of the fluorescence. Finally, the electrical signal is compared to the modulation of the optical signal to determine whether or not the fluorophore is present. The present method can be used alone or in conjunction with known methods of optically analyzing fluorescence of fluorophores to determine the presence of fluorophores.

Abstract: The conventional grating is substituted by one or more curved prisms in a concentric spectrometer of the type derived from the Offner mirror objective. The curved prisms are known as Fery prisms. The deviations from the concentric form are used as a corrective device. The spectral apparatus is especially suited as an imaging spectrometer having a detector array because the two-dimensional image can be formed in the direction of the spatial coordinate as well as the spectral coordinate without distortions and curvatures.

Abstract: A shape meter for measuring the deviation from flatness of a moving rolled steel plate is disclosed. The shape meter includes a laser source for generating an illuminated spot on the steel plate. The laser spot must be separable or distinguishable from background radiation emitted by the steel plate. For instance, if the steel plate is hot and the laser source is an argon laser generating blue green light, the optical filter must pass the blue green light and filter the red thermal emissions. The laser light is directed onto the moving steel plate, and a detector measures the light scattered from the steel plate. The detector includes an optical filter, an optical lens, and a lateral effect diode sensor. A computer then calculates and reports the deviation from flatness of the moving rolled steel plate based on the scattered light measured with the lateral effect diode sensor.

Abstract: A method of inspecting the location of a polarization-direction changing film relative to a transparent plate at a predetermined position. The method comprises the following steps: (a) disposing a first polarizing plate to face a first surface of the transparent plate and at a standard position at which the first polarizing plate has inner and outer peripheries, in section, defining therebetween an area corresponding to a permissible range for location of a peripheral edge of the polarization-direction changing film; (b) disposing a second polarizing plate to face a second surface of the transparent plate, in which the polarization-direction changing film is located relative to the transparent plate; and (c) observing a locational relationship between the peripheral edge of the polarization-direction changing film and the area of the first polarizing plate through the second polarizing plate so as to make a judgment as to whether the peripheral edge of the.