Daniel R. Grieser

Real-time fingerprint verification system

Access to security spaces and the verification of credit cards require, ideally, a simple and inexpensive system that combines accuracy with a high resistance to compromise. We have been investigating such a system. This system incorporates a novel fingerprint input arrangement that permits the use of optical pattern recognition for fingerprint verification in real time. Test results together with design considerations are reported.

Nitric oxide measurements in a flame by laser fluorescence

Laser fluorescence measurements have been performed to detect nitric oxide in a CH(4)-O(2)-N(2) flame at atmospheric pressure. For these measurements a frequency-doubled tunable dye laser was used to excite the UV gamma-bands of nitric oxide. Sensitivities were adequate to detect naturally occurring levels of nitric oxide that were in the 20-30-ppm range. Higher sensitivities can be achieved using other currently available lasers having greater output intensities.

Hybrid incoherent optical pattern recognition system

A pattern recognition system that uses incoherent spatial filtering to recognize images directly from a narrowband phosphor television monitor is described. Images of real objects are captured with a television camera. These images are then edge-enhanced electronically and displayed on the TV monitor. The monitor output is used directly as the input to a holographic correlator. An optical multichannel analyzer at the correlation plane is used to analyze the shape of the correlation function and to determine the position of its peak. Experimental results agree well with theory. Concepts for handling rotation, aspect angle, and scale variations of the input are discussed.

The observations of defects in crossed glan-thompson polarizers.

Crystalline defects have been directly observed in crossed high quality Glan-Thompson polarizers and have been shown to be a major factor in limiting the attainable extinction ratio. The most important defects occur in the volume of the calcite. Surface defects have also been observed to limit the extinction ratio, but these presumably can be reduced by improved optical polishing. To our knowledge, this is the first direct optical observation of the importance of relatively minor crystalline defects in limiting the performance of Glan-Thompson polarizers. Our observation of large differences in defect density and the effect of these defects on the polarization behavior also explain why there can be orders of magnitude difference in the efficiency of Glan-Thompson polarizers manufactured under identical conditions. The defects were observed in a number of Glan-Thompson ellipsometer grade polarizing prisms. All the prisms examined were of quite high performance. The prisms were examined in pairs as described later and it was found that the lowest extinction ratio was 3.0 × 10 when the full aperture of the prisms was used. The first measurements were made using a 100-W point-arc high pressure mercury lamp as a source. A lens and circular aperture were used to obtain a collimated beam 8 mm in diameter and were followed by an interference filter to isolate the 5461-Å green line. One of the best performing prisms was placed in line as the polarizer. The remainder of the prisms were successively inserted 90 cm further down the optical bench as analyzers. A photomultiplier was used to measure the light transmission through the system, with a lens and pinhole employed in front of the P M tube to confine the measurement to rays parallel to the axis within 1 0 2 rad. The crossed polarizer-analyzer orientation was detected by a minimum in detector signal as the analyzer prism was rotated using a fine angular adjustment screw. A change in null signal could be detected within a rotation of the analyzer of about 0.25 min arc. The extinction ratio was calculated by dividing the product of a filter factor and the measured intensity in the aligned orientation by the intensity measured in the crossed orientation. Calibrated neutral density filters were used in the measurement of intensity for the aligned orientation in order to avoid saturating the detector. I t was found that not only did the measured extinction ratios vary from prism-to-prism but also were different when the prisms were turned end-for-end. In one extreme case, the ends differed in performance by a factor of 6. A 1-mW helium-neon gas laser was eventually substituted for the filtered mercury arc lamp as the source. The laser output beam was expanded with a pair of lenses from a 3-mm beam to about 8 mm in diameter. The polarizer prism was aligned with respect to the principal plane of polarization of the laser output. Extinction ratio measurements were repeated on several of the best prisms and yielded approximately the same values as measured with the arc source. The beam expanding telescope was removed and measurements made with the 3-mm beam indicated slightly higher extinction ratios. The beam was then reduced in size to about 1 mm diam, and this yielded the highest extinction ratios observed, which in the best case was about 3.0 × 10. I t was noticed that the crossed transmission was now quite variable with lateral position of the beam through the analyzer prisms. A long working distance microscope was set up in place of the detector system to permit looking into the prisms. In the crossed position, the light level was sufficiently low to permit comfortable viewing of the interior of the

Aqueous Corrosion of Uranium Fuel-Element Cores Containing 0 to 20 Weight Percent Zirconium

Abstract A description is given of the design and operation of a windowed autoclave system employed in the study of corrosion by pressurized hot water. The device has been used to obtain time-lapse motion pictures of the swelling and rupture of deliberately defected zirconium-clad uranium specimens. A method is described by which corrosion rates were calculated from pressure and temperature measurements. A typical set of pictures taken during a test is presented, and corrosion rates are reported for uranium-0, 5, 10, 15, and 20 weight percent zirconium alloys subjected to 600 F water. 8.4.5

Hybrid Techniques For Postal Address Location

Many real-world pattern recognition problems entail location of an image within a very cluttered environment. Hybrid processing can be valuable in such a situation by using the high-speed parallelism inherent in optical processing for the feature extraction step, since feature extraction is often the most time-consuming operation to perform digitally. The work reported here takes such an approach for finding addresses on cluttered mail. Two optical systems, a coherent spatial filtering system and an incoherent correlation system, are each discussed for use in combination with digital image processing techniques. Examples of mail processed and statistical results are presented.

Performance of High Visibility Wet-Night Highway Lane Dividers

Fresnel reflection of most of the light from auto headlights by rain water causes highway stripes to disappear and produces a strong glare against the dark road surface on rainy nights. Battelle has developed and demonstrated the feasibility of a low-profile highway striping design that has survived snowplowing and has remained effective as a wet-night lane divider on a high-speed, high-density traffic thruway.

Real-Time Diagnostics for a Laser Fusion System

An automated diagnostic system has been developed and installed on a multibeam laser for fusion research. Laser-beam phase and intensity profile, focal-spot profile, pulse width, beam energy, and other laser parameters are measured at a number of points in the system. Data from the optical and voltage sensing elements are processed by an on-line mini-computer and the information is presented in graphic, pictorial, and tabular form. The processed information is used

Aqueous Corrosion of Uranium Fuel-Element Cores Containing 0 to 20 w/o Zirconium

Abstract: A description is given of the design and operation of a windowed autoclave system employed in the study of corrosion by pressurized hot water. The device has been used to obtain time-lapse motion pictures of the swelling and rupture of deliberately defected zirconium-clad uranium specimens. A method is described by which corrosion rates were calculated from pressure and temperature measurements. A typical set of pictures taken during a test is presented, and corrosion rates are reported for uranium-0, 5, 10, 15, and 20 w/o zirconium alloys subjected subjected to 600 F water.