QC 351 A7 no. 27 / This edition has been prepared in order to include more recent information than was available at the time of the first printing. New material is not incorporated into the text directly but is placed at the end of each table. It will be found on pages B-133, C-12, D-12, and E-8.

QC 351 A7 no. 45 v1 / "The Physics of Quantum Electronics," a two -week, noncredit course sponsored by the Optical Sciences Center, was held from June 15 through June 27, 1969, on the campus of Northern Arizona University in Flagstaff. The course was directed by Professors S.F. Jacobs (University of Arizona) and M.O. Scully (Massachusetts Institute of Technology) and was patterned after the tutorial symposiums sponsored in 1966 and 1967 by Colorado State University, and in 1968 by the University of Arizona. Designed primarily for advanced students, re- search scientists, and technical administrators working in the general area of quantum electronics and coherence physics, the course attracted 90 participants from all over the world. A list of attendees appears at the end of this report.

QC 351 A7 no. 45 v2 / The major areas of quantum electronics are concerned with the generation of electromagnetic fields- -with the theory and operation of stimulated emission devices, stimulated and nonlinear scattering phenomena, etc. A smaller but vital area involves the measurement problem, and explores the ways in which we can determine various properties of optical fields through measurements of intensities, interference, correlations, statistical distributions of photoelectrons, etc. In these lectures we will investigate various techniques for exploring the properties of optical fields. Until some 15 years ago all known optical phenomena could be described by the simple classical theory of elementary optics. In the mid 1950's, two new experiments were reported --the Hanbury- Brown Twiss intensity interferometry experiment, and the light beating experiment of Forrester and coworkers. These experiments generated considerable confusion since many people found in them an apparent violation of well -established physical principles. Subsequently, optics has undergone a revolutionary development with the invention of lasers and the introduction of fast pulse electronics capable of resolving individual photon detection events on a nanosecond time scale or less. The new field of photon statistics has grown rapidly and has already produced a sizable literature. Concurrently with the experimental developments, there has been a rather complete restructuring of the theory of optics which has produced a framework in which all of the newer experiments can be analyzed. A theoretical development has followed two independent paths. A classical theory of optical coherence has been developed, mainly by E. Wolf, based on the earlier work of Gabor and others. More recently, R. J. Glauber has formulated a quantum mechanical theory of optical coherence. Unfortunately, much effort has been expended in trying to prove both the equivalence and the nonequivalence of the two formulations, an undertaking which has produced considerably more heat than light. In these lectures we will attempt to review both the classical and quantum mechanical theories of optical coherence, and will use the results to analyze a variety of experiments. The emphasis throughout will be on gaining physical insight rather than on maintaining mathematical rigor. For those interested in detailed discussions of the theory, references to the literature are included in these notes.

QC 351 A7 no. 50 / The results of the first complete tests of the Optical Sciences Center digital image processing facility are reported. The instrumentation for digitizing film transparencies is operating well enough to provide suitable in- puts to the computer program IMPR(C, which processes (restores) the degraded image. Some manual correction of the digital data is required (mainly for missing digits) before IMPROC can be used. Although IMPROC will be expanded and modified during future research efforts, the debugging of its present form is essentially completed. First attempts at restoration of a defocused image show contrast enhancement and edge sharpening. Current techniques for displaying the processed images, however, are slow and have a limited gray scale. The best technique to date, which uses the computer's plotter to produce nine distinguishable gray levels, requires 1 hour to produce a 100 x100 matrix of points. A CRT film display device, driven by a digital computer, is being developed to solve this problem. Current and future research efforts are described.

QC 351 A7 no. 60 / The atmospheric transmission and airlight in three spectral bands as a function of an angle off nadir were calculated from radiometric measurements with cameras and film for a particular solar irradiance and atmosphere; the sun zenith angle was 49 °, the airpaths were from 15,000 ft m.s.l. to the surface at 1,900 ft on a clear day in Tucson, Arizona, and the azimuth was into the sun. The three spectral bands had peak transmissions at 430 nm (blue), 530 nm (green), and 800 nm (infrared). The statistics derived from numerous measurements show that a standard deviation of 2% can be attained in the relative radiances read out of multiband photography obtained with calibrated cameras and processed with carefully controlled sensitometry. In the blue and green bands, the atmospheric effect on contrast as a function of an angle off nadir became statistically noticeable at about 35° and 50 °, respectively. The standard deviations of the relative radiances measured in the blue and green bands were 3% and 2 %, respectively. The effect in the infrared band probably became significant at even larger angles; greater inaccuracy in the infrared band data precludes a more definitive statement. Also presented is a solution for an optimum ratio of playback lamp luminances for false color recombinations in two bands.

QC 351 A7 no. 70 / In order to find a new and more economical method for the computer detection of object outlines in aerial photographs, the human visual system is considered. This leads to the concept of the human retina as a matrix of light receptors and permits the development of a three-stage retinal process. The first stage consists of the registering of the intensity distribution of the image. The second and third stages consist of operations that are analogous to the mathematical calculations of the first and second derivatives. This process is applied to the retinal matrix in a line-by-line method in two orthogonal directions. This retinal model is tested experimentally and applied successfully to two photo- graphs. The computer program that generates and performs the retinal three-stage process does so with a minimum of computer decisions, resulting in a highly efficient use of computer time. The successful application of this retinal model and its inherent economy of operation demonstrate its potential usefulness in the computer analysis of aerial photographs.

QC 351 A7 no. 71 / Generalized ray tracing is a method of calculating the principal curvatures and directions of the wavefront associated with a ray as it is traced through an optical system. The results of such a ray trace provide important information about the structure of the image and have immediate application to lens design and image analysis. The caustic surface formed by an optical system can be easily determined from the results of a generalized ray trace. An examination of several caustic surfaces formed by different optical systems provides valuable information about the relative quality of the images and indicates some of the advantages of the generalized ray tracing method.

QC 351 A7 no. 74 / Measurements of the scattering of reflected light as a function of angular separation from the specular direction were made on aluminum-coated flat glass samples with surface roughnesses ranging from 1.0 nm to 70 nm rms deviation from the mean surface. Small -angle scatter (measured between 0.33° and 1° away from the specular direction) was investigated using light that had passed through a narrow slit; a measure of the scattering magnitude was provided by comparison of the far -field diffraction patterns produced by the slit, reflected from the samples and without the samples in place. The slit used to produce the diffraction patterns was optically processed to be smooth enough so that without the sample in place the minima of the diffraction pattern would be well defined and of lower magnitude than the scattered flux produced when the samples were in place. By considering the effects of the scanning aperture, it was determined that the measured magnitude of the minima agreed with those predicted by the use of Kirchhoff theory to within a factor of three. Comparison of small-and large-angle scatter measurements made on the same set of samples indicated that a transition region between the two types of scatter may exist in the region of 1° to 5° away from the specular direction. Because separate instruments were used for the small-and large-angle measurements, the results are expressed in terms independent of the measuring instrument's geometry. The measured results were compared to a theory in which the choice of the scatter function, and by implication the autocorrelation function, could be arbitrary. This comparison revealed that the choice of the hyperbolic secant function, rather than a Gaussian function, provided a good fit to the small-angle data. By fitting a curve to the small -angle data, it was possible to estimate the autocorrelation length of the surface roughness as well as the peak value of the scattering profile. The scatter measurements for the smoothest sample ranged from approximately 3 X 10' per µsr near the specular direction to 10 -13 per µsr at wide angles. For the roughest sample, the range was from 3 X 10-4 per µsr to 10-10 per µsr.

QC 351 A7 no. 81 / A number of laboratory tests have been carried out at the image tube laboratory of the Optical Sciences Center on 11 selected image intensifiers in order to compare and evaluate their performance. The electrostatically focused tubes tested are as follows: ITT F-4708 (1 stage), two samples of a Varo 8605 (1 stage), Varo 8605DC (1 stage), ITT F -4724 (3 stages), RCA 8606 (3 stages), and Varo 8606 (3 stages). The magnetically focused tubes are EEV P829D (5 dynodes), ITT F-4089 (1 stage), RCA C33011 (2 stages), and RCA C70021AEP2 (3 stages). The tests included measurements of limiting resolution (of the intensifiers directly and of photographs obtained with the intensifiers), square -wave response, geometrical distortion, shear characteristics in fiber-optic faceplates, photographic speed gain, uniformity of response, light- induced background, dark emission, and detective quantum efficiency (DQE) of intensifier -photographic emulsion combinations. The most significant result of the tests is that a comparison among tubes with a similar number of stages (or gain) showed that the magnetically focused intensifiers were generally superior to the electrostatically focused intensifiers in resolving power, geometrical distortion, and uniformity of response. However, the electrostatically focused tubes exhibited only about one fifth the light- induced background of the magnetic tubes. Also, a mean relationship was found between the limiting resolution of the intensifier output image and the limiting resolution that is recorded on a photograph of the intensifier. Other particularly notable results include (1) the causes and characteristics of several different types of response nonuniformities, (2) the identification of sources of light -induced background, (3) the photographic speed gain required of an intensifier to obtain the highest peak DQE possible and also that required to make the system behave as a "single- photon event" detector, (4) the identification of some especially undesirable characteristics of a potassium chloride transmission secondary emission (TSE) dynode intensifier (EEV P829D), and (5) the performance of three relay lenses for intensifiers.

QC 351 A7 no. 82 / The object of this study was to determine the utility of polarization -discrimination techniques for active optical processing. A baseline of static performance must be established before these techniques can be applied to real -time processing. The theoretical foundation for an alternative to the Vander Lugt technique of re- cording complex spatial filters had been laid by Marathay in 1969. On the basis of his theory, a photosensitive Vectograph TM technique was investigated, in which the image is produced as a polarization pattern rather than as the silver grain image of conventional photography. (1) Photographic characteristics of sensitized Vectographs were determined. The resolution ( >700 1p /mm) and the gray scale achieved indicate that the Vectograph material can also be used for recording Vander Lugt filters. (2) Theoretical analysis showed that the technique can be used to image and process objects in the same system without removal of the filter. It can also be used to generate halfwave plates for the pupil functions described by Toraldo di Francia for superresolution. (3) The Vectograph can perform addition and subtraction of functions recorded on it; it also is suitable for recording real -bipolar filter functions. (4) Variable- contrast images can be recorded. A variable-contrast Vectograph tar- get (VCVT), developed for optical testing, can not only vary the contrast of the recorded image but also reverse its contrast. In a similar fashion, a spatially variable birefringent filter (SVBF) was developed that permits spatial control of the wave- length of the transmitted light. Static and dynamic electro-optical properties of liquid crystal mixtures of cholesteryl-chloride, cholesteryl-nonanoate, and cholesteryl-oleyl-carbonate were studied to determine their feasibility as the modulator in a proposed photoconductor-liquid crystal sandwich, which would be used as a reversible recording medium. (1) Previous research had indicated that cholesteric liquid crystals are circularly dichroic in a narrow wavelength band. The present work showed that light transmitted within this band is actually elliptically polarized. The degree of ellipticity depends on the relationship between the probing wavelength and the wavelength at which the sample becomes circularly dichroic. Outside this narrow wavelength band, the crystals exhibited pure optical activity. (2) The dynamic electro-optical properties of the cholesteric trimixture were measured. An alternating electric field applied parallel to the helical axis of the liquid crystals resulted in a hysteresis in the electro-optical rotatory power of the crystals. The magnitude of the hysteresis would limit cycling of these liquid crystals to a maximum frequency of ^0.10 Hz. (3) A bias voltage applied to the crystals in an attempt to improve the frequency response resulted in a field- induced memory. When the bias voltage was maintained, the optical rotatory power failed to stabilize. Prolonged exposure to the bias voltage severely diminished the electro-optical rotatory power of the crystals.