Abstract: A method of calibrating a flow cytometer is based on a set of highly uniform microbeads associated with a fluorescent dye in such a way that the microbeads have the same excitation and emission spectral properties as the samples which are to be measured. The calibration values of the microbeads are plotted against the relative fluorescence intensity peak channel for each microbead in the set. From this calibration plot, the relative fluorescence intensity peak channel of the sample is translated into equivalent soluble fluorescent dye molecules per sample particle. The calibration values of the standard microbeads are determined against solutions of the dyes.

Abstract: A beam of light, such as a laser, is used to scan across a lens. The beam passing through the lens is modulated by an optical encoder which controls the amount of the beam passing through the encoder to a light receptor. The received light is quantified and processed to determine any distortion caused by the lens. The encoder is comprised of a set of transparent windows upon an opaque face, the windows having a certain pattern that a beam travelling across the windows casts a specific light intensity pattern. The encoder also allows determination of astigmatism of the lens and distortion inherent in the beam itself.

Abstract: Monitor signals are produced which are qualitative or quantitative measures of the shape, size or position of a light spot on an optical head relative to fibre-optic receptors in the optical head. One pair or two pairs of receptors may be used. Production of the monitor signals involves modulating the incident light forming the light spot at a predetermined frequency, delaying the light signals in one or more of the fibre-optic receptors relative to the light signals in one or more of the other receptors by, say half a wavelength of the predetermined frequency, combining the outputs of the fibre-optic receptors to produce a compound light signal, producing an equivalent compound electrical signal by means of a photodiode, and processing the compound electrical signal in electronic processors to extract one or more of its components to act as the monitor signals.

Abstract: An apparatus and a method for measuring a mode partition characteristics of laser diode with so-called a k-value (k factor), in which the PN (Pseudo Noise) pulse pattern is used for modulation of laser diode to be measured on the occasion of measuring various parameters required for calculation of the k value.

Abstract: A photomask comprises a tested pattern (P.sub.1, P.sub.2) and a synchronization pattern (SP.sub.1 .about.SP.sub.8). The synchronization pattern is used for synchronizing a scanning signal (S.sub.9), obtained from the tested pattern, with a reference signal (S.sub.10), based on a reference pattern data stored on a magnetic tape (7).

Abstract: FM laser spectroscopy apparatus includes a single modulator for modulating a laser beam with first and second modulation signals (.omega..sub.1, .omega..sub.2). The two modulation signals are generated by mixing a signal from a first oscillator (.omega..sub.1 +.omega..sub.2)/2 and a signal from a second oscillator (.omega..sub.1 -.omega..sub.2)/2 and producing the two modulation signals (.omega..sub.1, .omega..sub.2). The modulator produces three groups of sidebands on the laser beam at the laser frequency plus and minus the two modulation frequencies and at plus and minus the difference between the two modulation signal frequencies. The apparatus provides practical high frequency FM spectroscopy as required for the observation of pressure broadened spectral features.

Abstract: A method of inspecting a pattern of elements on a working plate includes producing a negative copy of the working plate and aligning the negative copy with a positive inspection plate having elements slightly larger than the elements of the working plate whereby flaws are revealed as light transmissive spots. The working plate and a negative inspection plate, having the elements slightly smaller than the elements of the working plate, are aligned and flaws are revealed as light transmissive spots.

Abstract: In a flow cytometer where the laser beam is larger than the size of each biological cell of a column of cells being passed through the laser beam at a high rate wherein new and improved method and means are used to calculate the size of the cells as sensed by low angle forward light scatter or secondary emission of fluorescent material on the surface of the cell by measuring the time-of-flight of the smaller cell across the laser beam, with the time-of-flight being measured by integrating an electrical signal from either the forward light scatter or the secondary flourescent emission from a single cell as it passes through the laser beam and deriving still another electrical signal measuring the peak amplitude of the first signal and then dividing the integrated signal by the peak signal and subtracting a constant electrical signal from that quotient.

Abstract: A first photographic image (1) in the form of a hologram of the tooth (2) and location points (3) near the tooth taken on the occasion of the first examination is placed alongside a second photographic image (4') in the form of a hologram of the tooth (2') and location points (3') near the tooth taken on the occasion of the second examination. Adjusting devices (5, 6, 7) are provided to permit the displacement of the first photographic image (1) relative to the second photographic image (4'). This will bring the location points (3) on the first photographic image into line with the location points (3') on the second photographic image (4'), whereupon the displacement of the tooth (2) may be determined as the difference between the position of the tooth in the first photographic image (1) and the position of the tooth in the second photographic image (4').

Abstract: A photometric reading device comprises a plurality of reading elements (30), each comprising a light emitting diode and a corresponding photodiode on opposing sides of a sample pathway along which a sample microplate (10) can travel. The microplate (10) includes rows of sample wells arranged transverse to the line of relative motion of the microplate (10) and the reading elements (30).The reading elements (30) are arranged such that, during continuous relative motion of the reading elements (30) and the microplate (10), the reading elements (30) come into registration sequentially with the wells in the first row of wells in the microplate (10), then with the wells in the second row of wells, and so on.

Abstract: A process and apparatus for qualifying a reticle, master pattern, or the like, in-situ as it is used in a system for photolithographically creating an image on a substrate, including the steps of coating a transparent substrate with a layer of transparent photoresist material, placing the coated substrate with a layer of transparent photoresist material, placing the coated substrate on a substrate supporting means, using a source of illumination in combination with a reticle, or master pattern, to create an image of the reticle, or master pattern, on the substrate, thereby exposing the photo resist coated on the surface thereof, removing the substrate from the supporting means, developing the exposed photoresist to produce a transparent patterned mask on the surface of the substrate, said patterned mask corresponding to the pattern on the reticle, or master pattern, and, in combination with the substrate, forming a monitor object, inspecting the monitor object by passing light through both the transparent mas

Abstract: The measurement of weak absorption lines is facilitated by the use of a long transmission path length, which is difficult to obtain in compact or portable instruments. In the present invention, light is made to travel through a limited volume of gas thousands of times. The light is placed on a closed optical path on which it circulates through the gas sample. After a desired number of passes through the gas sample, the light is removed from the closed optical path. Introduction of the light to the closed optical path and removal therefrom is accomplished through the use of a polarizing beamsplitter and a pockels cell located on the closed path. Light is put onto the closed path by the polarizing beamsplitter which imparts a specific polarization. During the first circuit the pockels cell alters the polarization by 90 degrees thereby preventing the light from escaping back out through the polarizing beamsplitter.

Abstract: A luminometer construction including means for supplying samples contained in respective cuvettes 20, in succession to be examined, the cuvettes being introduced into a carrier 10 having a cuvette gripper 19, the carrier 10 defining an examination chamber 21 into which the cuvettes are inserted, the carrier 10 being rotatable between a loading and a test position in which the examination chamber 21 is adjacent to a photo-multiplier device 25, whereby testing of a sample in a curvette 20 can be carried out, the examination chamber 21 having an edge in a plane inclined to the axis 11 of rotation of the carrier 10, and the photo-multiplier device 25 being arranged with its optical axis 26 perpendicular to such plane.

Abstract: A method and apparatus is disclosed for detecting defect surface states in any material and in particular semiconductors. In the subject device, a periodic localized excitation is generated at the surface of the sample with an intensity modulated pump laser beam. A probe laser beam is directed to the surface of the sample and changes in the probe beam which are in phase with the modulated pump frequency are detected. In the preferred embodiment, periodic changes in the optical reflectivity of the surface of the sample induced by an intensity modulated excitation beam are detected by measuring the corresponding modulations in the reflected power of the probe beam. Any time dependence of the probe beam modulated reflectance signal is monitored. An evaluation of defect surface states is then made by investigating the time dependence of the magnitude and/or phase of this probe beam modulated reflectance signal.

Abstract: The method for measuring dimensions of a workpiece (15) in a coordinate measuring machine having an optical probe (14) arranged to output radiation in a direction (21A) at an angle to a surface (15A) to be measured. The probe has a housing (17) which is arranged to lie clear of a projection formed by the surface (15A) to be measured and another, adjacent, surface (15B) so that the housing can pass clear of the projection and the measurement can be made without halting the machine at the surface to be measured.The probe (14) is adapted for the radiation to be in the form of a cone (21) symmetric about an axis (Z1) transverse to the direction of movement of the probe so that the probe can sense all around the axis and therefore can sense any surface parallel or inclined to the axis regardless of the direction in which the surface faces.

Abstract: A specific small area of a crystal sample is scanned by a laser beam which rotates about an axis substantially perpendicular to the sample surface such that the intersection of the beam with a plane above and parallel to the surface describes a true spiral or a stepwise spiral pattern. The laser beam is reflected different amounts for different beam positions to produce a reflectance pattern indicative of crystallographic orientation.

Abstract: YAn apparatus for and a method of adjustment, in the lateral direction, of the light beam of a vehicle headlight, in its low beam position. The light beam extends on one side of a cut-off line. At least two vertically extending, elongated photoelectric cells are placed in the light beam, in such a manner that the upper part of each photoelectric cell is not illuminated by the headlight and which the lower part is illuminated, regardless of the position of adjustment, in the vertical direction, of the headlight. When the headlight is at its position of correct lateral adjustment, the electrical signals supplied by the photoelectric cells have a specified ratio. In laterally adjusting the position of the headlight, the electrical signals supplied by the photoelectric cells are brought to the specified ratio.

Abstract: Parallel light rays are applied to a cylinder and true exit positions of the rays from the cylinder are measured, phantom exit positions for the incident rays are calculated by using a mathematical function representing a phantom refractive index profile, and the mathematical function is modified so as to minimize the sum of the squared differences between the true and phantom exit positions.

Abstract: Optical metrology method and apparatus in which the sheared portions of an optical image are automatically aligned so as to enable the widths of high contrast lines to be measured using optical image shearing. A mechanism splits a line image of an object into two, shears the two images and records the displacement distance, and an imaging system e.g. a television camera generates an electronic signal which represents the intensity profile of the sheared image in a direction perpendicular to the line image and parallel to the direction of shear. The intensity profile of the sheared image is sampled and digitized, and the digital signal is correlated with a digital filter. A mechanism then adjusts the shearing to a position given by an electronic signal, and the two positions taken up by the shearing mechanism are recorded, the difference therebetween is calculated, and then multiplied by a calibration constant, to provide line width information to be displayed on a display device.

Abstract: A method of detecting a registration diversion between a mask and a wafer prior to a main exposure. This method detects relative diversions between marks on the wafer and latent images of marks on the mask formed on a photosensitive layer of the wafer. The latent images of the marks on the mask are preliminarily formed on the photosensitive layer of the wafer by an exposure energy beam prior to the main exposure.