Laser technology is recognized as an important new innovation of the Space Age. A Laser Hazard Classification Guide published by the National Institute of Occupational Safety and Health in July 1976, lists nearly 2,500 different models of lasers. SPIE has published proceedings available on Low Power Lasers, High Power Laser Technology, and Ultra High Power Lasers.
The iodine stabilized helium-neon laser is the most accurate and stable standard of length that is available for general metrological use today. Although the krypton discharge lamp is still the basis for international agreements which define the meter as the length standard, the independent reproducibility of the iodine stabilized helium-neon laser has been shown to exceed that of the krypton lamp when international intercomparisons are made. Because of its superior performance, the iodine stabilized helium-neon laser is used in most national standards laboratories to realize the standard of length. A value for its wavelength which is consistent with the value for the wavelength of the krypton lamp has been agreed upon by the metrological community through consultation with the International Bureau of Weights and Measures.
The purpose of this paper is to give an overall view of the Laser, Electro-Optics Technology Department at Vincennes University. Objectives, educational approach, curriculum, laboratory emphasis, and industrial relations will be presented. When industry needs to select a technician in optics, electro-optics, or lasers, only a handful of qualified technicians will be available. This is due to the fact that these fields are fairly new and the number of schools offering these programs is limited. As the Program Coordinator of the Laser Electro-Optics Department at Vincennes University, I am confident that our school will provide highly capable technicians. The program at Vincennes University has full North Central Accreditation and offers a broad variety of courses in order to provide employers with technicians having the best possible electro-optical training. Sixty per cent of the total instruction time is spent in the laboratory, in which the emphasis is on individual participation in each of the labs. The students' educational backgrounds vary from high school credit by G.E.D. to bachelors degrees in various areas.
The Zygo Laser Telemetric System is a field proven, second generation gauging system for high speed, non-contact dimension and position measurement and control. Ruggedly constructed, the system measures outside diameters, multiple dimensions or part position of either opaque or transparent objects, e.g. glass, metals, plastic or rubber, on-line and in harsh industrial environments. Many LTS's have been produced and applied. This paper reviews not only some of the interesting installations but also technical features of the Model 120 that have contributed to their success.
This paper describes a semi automatic gage comprised of a solidstate image sensor, a microprocessor, light source, fiber optics, lens system, and a mechanical fixture to measure the size and location of two small slots inside a diesel engine fuel injector nozzle. The slot widths and locations are measured to a resolution of .002 millimeters with a maximum measurement of 30 millimeters. Designed for production inspection, the operation is extremely simple and easily performed by an unskilled operator. This ease of operation also carries over into the calibration of the gage which takes about 15 seconds. During the calibration, a known master gage is measured by the system which then computes and stores in the microprocessor memory the scale factors and offsets of each of the measured variables. In operation, the production nozzles are measured using these stored scale factors and offsets, displayed in millimeters, and compared with the part tolerances stored in memory for an accept/fail indication. By replacing the fixturing and and modifying the computer program, the unit can be configured for a variety of high precision measurement and inspection applications.
Production and quality control managers are counting on automatic visual inspection to automate the last labor intensive factory operation. Image analysis, laser scanning and coherent optical processing have been used with varying degrees of success to solve particular production line inspection problems. In this paper we discuss four diverse applications: needle point inspection, fabric inspection, small part color verification and cotton trash measurement. Each of these problems is solved by a different technique. In particular, needle point inspection accomplished by diffraction pattern analysis, fabric inspection by coherent optical scanning, small part color verification by on-line spectrophotometry and cotton trash determination by coarse image sampling and processing. An overview of these four applications shows why the particular approach is chosen for each and illustrates the generic problem solved by each technique.
Because this Seminar is sponsored by SPIE and ASQC, I am assuming there is a broad range of interests represented by the audience. We've tried to orient this paper to cover the interests of both societies. However, because of the nature of our work and interest, this paper is weighted more to user applications for inspection, calibration and problem solving. We hope we have something for everyone. We'll be showing schematics of the various optical accessories and their applications. We'll be looking at the Laser Interferometer interfaced with the calculator for immediate data processing for statistical analysis. With immediate data processing we can easily repeat a measurement for data confirmation should there be some question regarding the results. In some instances, we can interface the calculator to other instruments for data analysis. Again with the calculator on the job - literally -data confirmation is easy.
A line of new instruments is described which use light scattering to measure various parameters of particulate distributions. Employing laser illumination of a flowing stream of particles, a Fraunhofer diffraction pattern is produced and processed with optical and electronic means. Various parameters of the particle size distribution are measured, including a thirteen segment histogram of the volume size distribution. The measurement is rapid and continuous. Technical background and instrumentation is discussed. Many applications have been made, and this paper includes three examples relating to industrial quality control involving particles.
The past several years have seen a dramatic increase in the application of electro-optical techniques to the problems of mechanical alignment. Although these problems have existed for a long time, the applications are new and have required significant developments in position sensing detectors. UDT's lateral effect photodiodes and the systems using them represent state-of-the-art in position sensing. The discussion will include physics of these position sensing detectors and the presently available specifications.
Although man has been judging produce quality via light since antiquity, it has been only during the past 50 years that detectors other than the human eye have been available. The initial significance of photoelectric detectors was in providing instruments which brought new objectivity into the evaluation of color and appearance. The progress in objectively rating the color of agricultural products during the period 1930 to 1960 is covered in the publications of Dorothy Nickerson (1946). During this period numerous color specifications for agricultural products were written. Many color standards, such as the Munsell "Soil Color Charts," were prepared. The methods for visually rating color are well developed and are fully described in books on color; e.g. Judd and Wyszecki (1975) and literature of the Munsell Co., Baltimore, Md. Limitations in this method of evaluating color are basically human factors. Efforts at eliminating these limitations brought about widespread use of the color difference meter.
Battelle, Pacific Northwest Laboratories has developed an advanced cartridge case measurement/eject system (CCMES) which automatically inspects and rejects cases at up to 1200 per minute. The system consists of a mechanical handler, measurement instruments, and a dedicated computer. System operation is monitored and controlled while the product is being measured. Five case dimensions are measured by an electro-optical system using, diode arrays to measure a case image at unity magnification. By scan averaging, measurement standard deviations as small as 2.5 microns are obtained at a throughput of 1200 cases per minute. Measurements made with the system fall within the uncertainties of hand-gauged values for the same cases. Four zones on each case are examined for surface flaws, such as dents and scratches, by detecting light scattered from the surface. The system can detect these surface flaws at inspection rates of 1200 cases per minute. Using electro-optic methods, two additional measuring stations detect vent hole presence and gross size deviations to prevent mechanical jams. A third station employs an eddy current technique to detect splits and folds in critical regions of the cartridge. The overall system has passed quality assurance tests administered by the sponsor and will soon be installed at the Lake City Army Ammunition Plant.
Proc. SPIE 0129, Inspection Of Parts In Micro-Inches With A Closed Circuit Television System Or How To Measure To A Half-Millionth Of An Inch Without Hardly Trying, 0000 (28 February 1978); doi: 10.1117/12.956019
In the final stages of development at the National Bureau of Standards (NBS) is a photo-mask-like physical standard for the evaluation and calibration of linewidth-measuring optical microscopes, including those of the automatic, closed-circuit TV types. The standard bears clear and opaque lines in the 1 to 10 micrometer (40 to 400 microinch) range and is applicable to microscopes used to measure the opaque-type, as opposed to "see-through", photomasks in trans-mitted light. Primary calibrations of the standard are done on an electron microscope/laser interferometer system with secondary calibrations done on a high-performance photometric optical microscope. The NBS linewidth standard, having linewidths and linespacings distributed in a special way over the range where serious problems in industrial linewidth measurements occur, can be used to detect systematic errors and the biases within measuring systems which cause them. Given in this paper is a constructed numerical example, based on observed effects, of how use of the standard can reveal a number of different types of systematic errors within a single system and can point to likely sources of biases which cause these errors.