Abstract: An etch rate monitor for use with semiconductor wafer etching processes includes a source of light of normal incidence to the wafer surface through a window in the etching chamber. In a first embodiment, a Fresnel or positive lens is used to collect some of the diffraction orders caused by the repetitive patterns on the wafer surface which merge from the window. In alternate embodiments, a concave spherical mirror and/or a photodetector system are used to collect the diffraction orders. A collimating lens applies these diffraction orders of normal incidence to interference filters which reject plasma and ambient light and pass the diffraction orders to a photodetector to monitor etch rate as a function of the cycle period between interference minima or maxima caused by the difference in path length between the etched and not etched surfaces of the wafer.

Abstract: A photometer having a plurality of input fibers to its optical entrance, at least one of which is for transmission of calibration light and at least one of which is for transmission of sample light. The exit ends of these fibers are aligned into a linear array, thereby producing an effective entrance slit for the optical entrance of the photometer. The fiber(s) for calibration light are positioned at the center of the linear array to avoid miscalibration due to photometer astigmatism.

Abstract: An interventional therapeutic apparatus is described which includes a probe in the form of a transmission line such as coaxial cable. The probe is adapted to pass through the interior of a body cavity such as a blood vessel and includes an inductive load such as a ferrite bead at the remote end of the cable. Radio frequency energy is applied to the cable and converted into heat by a ferrite bead. As a result of the heat conversion by the ferrite bead, the remote end of the coaxial cable is heated to a sufficient temperature to provide the effect desired, for example to melt or otherwise remove plaque deposits in blood vessels.

Abstract: Apparatus and a method for providing measurements of the diffuse transmittance or reflectance of a sheet at a set of points arranged along a pattern line on the sheet. In accordance with the invention, the sheet, such as a photographic film, is moved with respect to a cylinder with a slot cut in its wall parallel to its central axis. A beam of radiation is swept parallel to the slot and into the cylinder after scanning along a line on the sheet. The inner wall surface of the cylinder is coated with a high reflectance material so that a fraction of the directly transmitted and scattered radiation in the cylinder enters one or more electronic radiation detectors coupled to the cylinder. The fraction of the radiation measured depends on the position along the slot of the radiation beam, and the data are corrected by dividing the measurement at each point by the measured radiation at that point when no object is in the beam. Several embodiments of the cylinder are disclosed.

Abstract: Particle distribution in a fluid flowing through a microscopic tube is achieved by flowing the fluid vertically-downward through a transparent capillary tube and passing light through the flowing fluid. A linear array of photodiodes responds to light passing through the fluid by registering a series of signals representing the linear projection of particles passing through the plane defined by the light source and the photodiode array. The fluid is supplied from a reservoir which can be selectively pressurized by a gas to control the egress flow rate of fluid. A syringe serves as the egress path from the reservoir and a rotatable stirring rod is disposed in the syringe to stir the egressing fluid. The syringe feeds a disposable assembly which includes a hypodermic needle feeding the capillary tube which is mounted between a microscope slide and cover in the path of the sensing light.

Abstract: X-ray information is encoded onto photographic film by placing an optical grating between the light-emitting scintillating screen and the photographic emulsion. Information at different energies is encoded by displacing the grating between exposures or by using static gratings with an energy-selective dual screen.