I remember many years ago being very impressed with essayists such as Hilaire Belloc and E. V. Lucas. I am just as impressed today! It is nearly fifty years ago that I first encountered the writing of these worthies in a volume entitled Essays by Modern Masters. Imagine my pleasure when a second volume appeared called More Essays by Modern Masters. Many of the essayists of the first half of this century were good friends and colleagues.

Recent industrial demands in the fields of microsystems and device miniaturization led to development of two major technologies, micro-electro-mechanical (MEM) and micro-optics. A promising team-up of these two technologies combined with microelectronics creates a rich enabling technology of micro-opto-electro-mechanical (MOEM) systems. All constituent technologies in MOEM allow for batch processing and embossing and include a micromachining process that makes them highly fascinating for commercial applications.

Micro-optical components, such as diffractive and refractive microlenses, micromirrors, beamsplitters, and beam combiners, have recently received considerable attention in the optics R&D centers and finally in the manufacturing community. This achievement is due to micro-electro-mechanical (MEM) technology that has demonstrated major improvements in overall performance and cost of optical systems while offering the possibility of relativity rapid transition to products for military, industrial, and consumer markets. Because of these technology advances, an industrial infrastructure is rapidly becoming established to combine micro-optical components and MEM-based microactuators for on-chip optical processing. Optical systems that once were considered to be impractical due to the limitations of bulk optics can now easily be designed and fabricated with all required optical paths, signal conditioning, and electronic controls integrated on a single chip. On-chip optical processing will enhance the performance of devices such as focal-plane optical concentrators, smart actuators, color separators, beam shapers, fiber data distribution interface (FDDI) switches, digital micromirror devices (DMDs), and miniature optical scanners. We review advances in microoptical components developed at the Rockwell Science Center. We also review the potential of on-chip optical processing and the recent achievement of free-space integrated optics and micro-optical bench components developed at UCLA, and DMDs developed at Texas Instruments.

To build three-dimensional micro-opto-electro-mechanical systems (MOEMS), new materials have to be designed. However, increased manufacturability results generally in modified/degraded optical, mechanical, and electrical characteristics. The paper presents a detailed analysis of p + silicon as an opto-electro-mechanical material for microresonators, and gives some hints on the problems associated with the use of low-temperature dielectric in electrostatic microactuators. All the relevant parameters of p + silicon are experimentally determined and process recommendations allowing improved quality are formulated. Charge injection and trapping in low-temperature dielectric are analyzed and their impact on the behavior of the electrostatic actuators evaluated.

Recent progress in micro-opto-electro-mechanical systems (MOEMSs) has enabled the realization of a variety of novel devices, which, because of their small size and low cost, have the potential to revolutionize the fields of communication, sensing, and actuation. These micro-optical devices can be classified as either free-space optical or guided-wave in nature, and here we focus on the latter. We review the research on this subject and discuss results from our own research. We also identify technology bottlenecks and discuss the recent trends in this dynamic field.

The demand for communication delay and connectivity improvements suggests that optoelectronic multichip modules (OE-MCMs), utilizing photonic and electronic technologies, may provide practical solutions for high-speed interconnection problems at the module level. Design and fabrication issues for integrating optical waveguide and multiple metal layers on a single substrate are described to facilitate the practical implementation of OE-MCMs. In particular, innovative device structures and fabrication strategies are proposed such that OE-MCMs can be fabricated in a batch mode by a well-established IC fabrication process without causing any fabrication compatibility problems. The proposed OE-MCMs utilize optoelectronic interconnection, multichip module packaging, and MEMS fabrication technologies at the module level, and the feasibility of the proposed OE-MCMs has been demonstrated through the fabrication, assembly, and characterization of prototypes.

Micro-electro-mechanical deformable mirrors (MEM-DMs) are solid-state electronic devices with small, movable reflective surface elements that can be used to manipulate the phase of optical wavefronts. MEM-DMs differ from more conventional continuous-facesheet deformable mirrors in that the movable surface of a MEM-DM consists of a set of segmented moving surfaces. The segmented, reflective surfaces of a MEM-DM give rise to larger diffraction effects than those provided by continuous-facesheet deformable mirrors. However, MEM-DMs are still attractive due to their low cost and the low drive voltages. We explore the theoretical limits of performance of MEM-DMs for controlling fixed aberrations in optical systems, and we present laboratory results demonstrating reduction of a fixed aberration using a MEM-DM device. Results presented here show that while a MEM-DM does provide some degree of aberration control, diffraction effects arising from the static support structures of the MEM-DM surface are significant. An alternative design that uses a lenslet array in conjunction with the MEM-DM is shown through theoretical studies to provide superior aberration correction with lower residual effects due to diffraction.

The utilization of micro-optical components in systems for optical-beam deflection and modulation offers the possibility for realization of miniaturized switches and scanners. As the required displacement of the micro-optical components for efficient beam manipulation is quite small, high-speed actuators with small electrical power consumption can be used. We present a variety of micro-optical configurations and discuss their potential for the creation of different types of miniaturized scanners and switches. The combination of micro-optical components already available and semiclassical piezoelectric actuators leads to new types of switching and modulation systems for a very broad spectrum of applications.

Rockwell is working on the development of a micro-electromechanical optical scanner based on bimorph microactuators. This scanner is lightweight, is small, and has superior scanning performance. The scanner is a low-power (<1 W) device that has large scan angles (?20 deg) and scan rates in the range of 100 to 2000 Hz. It works for all wavelengths and offers the potential for monolithic integration with both electronics and optics for on-chip signal processing and control. The optical scanner consists of two main components—actuator and mirror— which are fabricated on a silicon cantilever beam. The actuator is comprised of a bimorph layer covered with two metal layers, which function as top and bottom electrodes. The mirror can be as large as 12 mm2 in area, is placed at the end of the cantilever beam, and is designed for maximum optical flatness. The optical efficiency of the device is very high and can exceed 90% on proper metallization of the mirror area. The scan angle is a function of beam thickness, power efficiency of the bimorph, and many other design criteria. Through many improvements in these design parameters, a scan angle greater than 20 deg is expected to be achieved with high yield.

The authors describe the development of a new type of micromachined device designed for use in correcting optical aberrations. A nine-element continuous deformable mirror was fabricated using surface micromachining. The electromechanical behavior of the deformable mirror was measured. A finite-difference model for predicting the mirror deflections was developed. In addition, novel fabrication techniques were developed to permit the production of nearly planar mirror surfaces.

A multi-point dynamic displacement probe was developed for measuring dynamic displacement and deformation. In this probe, a selffocusing micro-lens array (SMLA) replaces a microscope objective normally used in autofocus sensors, and an acousto-optic deflector (AOD) is used as a scanner to allow the collimated laser beam to scan the SMLA, namely, allow the focused spot to scan the sample surface. Due to the very high scanning speed of the AOD, the relative position of many points, and thus the dynamic deformation, can be measured in near real time. The method’s principles, accuracy, and error sources are described.

LIGA technology has been used to fabricate linear gratings having free-standing nickel walls a few micrometers wide and as much as 50 µm high, with period on the order of 10 µm. With additional MEMS processing steps, such devices are intended for use in a tunable infrared filter. Prediction of optical performance is a particularly challenging problem for gratings with these parameters and materials and requires a robust Maxwell solver. We have applied our own code, described elsewhere, in the form of a finite-element implementation of the equivalent variational problem, to examine the optical properties of this class of gratings. Here, we describe our predicted results for the transmittance as a function of wavelength and polarization for various grating parameters and incident conditions. Measurements of fabricated gratings were also carried out, and the predictions are shown to agree well with the measured data. The filter cutoff is shown to be sensitive to the cone angle of the incident radiation, and the implications of this effect for system performance are discussed.

The large detector size of conventional focal plane arrays (FPAs) often acts as a limiting source of noise currents and requires these devices to run at undesirably low temperatures. To reduce the detector size without reducing the detector’s quantum efficiency (QE), we have developed efficient on-focal-plane collection optics consisting of arrays of thin-film binary-optics microlenses and photoresist-based refractive microlenses on the back surface of hybrid detector array structures. Photodiodes of p/n polarity, of an unusual planar-mesa geometry, were fabricated in epitaxial HgCdTe deposited by molecular beam epitaxy (MBE) on the front side of a CdZnTe substrate. Diffractive (8- to 16-phase-level) Ge microlenses were deposited on 48-µm centers in a registered fashion (using an IR mask aligner and appropriate marks on the front surface of the CdZnTe) on the back side of the substrate using a lifting process. The lifting circumvents some of the process limitations of the more conventional chemical etching methods on diffractivemicrolens processing, allowing the microlenses to approach more closely their theoretical efficiency limit of .95%. Photoresist microlenses were fabricated by reflow of photolithographically defined photoresist islands. Prior to microlens deposition, but after diode fabrication, the test structures were flip-chip bonded or ‘‘hybridized’’ using indium interconnections to metallic striplines that had been photolithographically deposited on sapphire dice (a process equally compatible with a siliconintegrated- circuit readout). After hybridization, the CdZnTe was thinned to equal the focal length of the lenses in the CdZnTe material. Optical characterization has demonstrated that the microlenses combined with the detector mesas concentrate light sufficiently to increase the effective collection area. The optical size of the mesa detectors being larger than the theoretical diffraction limit of the microlenses precludes determining whether the lenses themselves produce the theoretical diffraction-limited gain, but they clearly decrease the required detector area by at least 3 to 6 times. To our knowledge, this is the first successful demonstration of IR detectors and binary optics and of photoresist refractive-microlens integration.

The technology of low-cost high-quality micromachined adaptive mirrors is reported. Adaptive mirrors are fabricated by combining bulk silicon micromachining with standard electronics technologies. Mirrors with tens of control channels, having RMS initial deviation from plane of the order of ?/20 and a range of surface deflection of 10 to 20 µm with linear frequency response in the range of 50 Hz to 1 kHz, are fabricated on standard PCB substrates. Advanced devices with hundreds of control channels, demanding integration of driver and switching electronics, are currently under development.

Low-cost linear arrays of deflectable micromirrors using a CMOS-compatible process to define both on-chip circuitry and the mirror structure are presented. The mirrors consist of the CMOS second metal layer deposited in two successive passes in order to establish a thick metal layer for the stiff mirror plate as well as a thin one for the flexible hinges. The mirrors are released by sacrificial aluminum and oxide etching. Supercritical point drying is performed in order to avoid sticking of the mirrors to the substrate. The mirrors are electrostatically deflected by biasing the address electrodes implanted into the substrate underneath the mirror plate. Full angular deflection by ± 4.8 deg of a 30 3 40-µm2 plate is achieved with a driving voltage of 11 V. On-chip circuitry adjacent to each mirror allows one to address the pixels with 5-V data pulses. The reflectance of the aluminum surface for wavelengths between 400 and 700 nm was measured to be 83% to 89%. The mirror surface was further characterized using Auger spectroscopy, showing that no optically relevant surface modifications occur during postprocessing. The surface rms roughness measured by atomic force microscopy is on the order of 25 nm.

We report a new magnetic MEMS technology that enables many electromagnetic MEMS devices. This new technology combines magnetic thin films and silicon bulk micromachining. Its use is demonstrated by two types of millimeter-sized analog scanning mirrors that are capable of delivering deflection angles exceeding 60 deg. Details include the design, fabrication, operation, as well as a complete electromechanical model of the mirrors. In addition, the use of the mirrors is further manifested in a holographic data storage system where hundreds of holograms have been successfully stored and retrieved.

A novel process for fabrication of single crystal silicon supported torsional micromirrors with large dimensions (300 X 240 µm) is presented. The mirrors consist of a sputtered aluminum film on a layer of supporting oxide mounted on fully suspended single crystal silicon grids. The grids have an aspect ratio of 7:1 to provide a stiff backbone and to ensure flatness of the mirror surface. Thus the mirrors do not bend due to the internal stresses. A new idea of actuation of torsional structures is also presented. Vertical near-comb type actuators were fabricated to drive the torsional structures.

A method for rapid alignment of laser beams in optical systems is presented. It employs a Seward alignment module (SAM) to qualify both the spatial position and angular direction of the beam. Alignment procedures for turning mirrors and laser mounts are described. Application of the SAM on two complex laser-etching systems is presented.

A scheme for aligning a bistatic lidar with liquid mirror telescope (LMT) is described. It is based on the fact that the axis of an LMT is absolutely vertical so that the focal point can be accurately found with a pair of vertically propagating helium neon laser beams, initially retroreflected from a liquid surface (such as the quiescent mercury surface of the LMT). When the detector is located at the focus of the parabolic reflector, the illuminating laser beam has only to be aligned absolutely vertical. This is done with an oil filled cup with a flat glass bottom.

A computationally efficient pyramid adaptive dynamic Hough transform (PADHT) is proposed to detect edges with arbitrary shapes and without prior knowledge. The binary pyramid structure is generated first. The edge map at the top pyramid level is obtained by using PADHT next. The edge map at each lower pyramid level is generated by PADHT also, but in a much smaller area determined by the edge map at the level immediately above. The analytic expressions of the arbitrary edge curves for the dynamic Hough transform are approximated by the rational Gaussian functions. The parameters of the Gaussian functions and the accumulated areas are changed adaptively according to the set of accumulated points. An energy function is used to determine which set of accumulated points represents the edge curve.

The conventional color edge detection methods generate color edge maps by calculating the vector gradient at each pixel. These methods may cause false edge detection for color stripe images and other special color images and they are sensitivity to noise. A new vector template matching method based on pyramid structure is presented. It can generate more precise edge points. The pyramid image structure has been used to reduce the computational cost in the multiresolution analysis. The effect of Gaussian noise can be reduced by selecting a suitable weighting function in the color pyramid generation. The edge interpolation, adjustment and smoothing are carried out to obtain edge map of a lower pyramid level from the edge map immediately above by the top-down strategy. The vector average median filtering is applied in this procedure to reduce the effect of impulsive noise. The method is applied to color palm images and another special images with both Gaussian and impulsive noise. Good edge maps are obtained from experiments.

The use of optical fibers is of particular interest to the telecommunications industry, due to the many striking advantages over traditional copper lines. These advantages cannot be realized, however, unless the mechanical integrity of the fibers is guaranteed. Therefore, the fact that certain environments can have detrimental effects on the mechanical properties of optical fibers is of great concern. In this investigation, both zero stress aging tests and two-point bending static fatigue tests were performed. The environments tested include buffer solutions of pH 4, 7, and 10, sodium chloride solution, unleaded gasoline, wasp killer, and deionized water. Zero stress aging in these environments had varying effects on the fibers, ranging from mild to severe reductions in fiber strength. Aging in the high-pH alkaline solutions produced severe reductions in fiber strength, whereas aging in the wasp killer, gasoline, and low-pH acidic environments resulted in relatively mild reductions in fiber strength. The static fatigue tests produced similar results, with stress corrosion parameters ranging from 5.5 for the pH 10 environment to 25.4 for the unleaded gasoline environment. ‘‘Fatigue knees’’ were also observed in the NaCl and pH 7 environments. Because of the fatigue knees, the stress corrosion parameters dropped from 25.3 to 3.7, and 19.7 to 3.1 for the NaCl and pH 7 environments respectively.

Some possibilities for binary 2-D fractal image characterization using correlation analysis of the transmitted light intensity fluctuations are discussed. These intensity fluctuations are produced by the probe coherent beam scanning of the studied object. Two different cases of diagnostics of the mass fractal structures are considered: with a broad collimated illuminating beam and with a sharply focused beam. Relationships between generalized characteristics of the studied structures (e.g., Hausdorff dimension) and asymptotic parameters of the structure functions of the intensity fluctuations (e.g., their exponents) are analyzed. Experimental results obtained with the specially prepared 2-D mass fractal structures (binary amplitude screens) are presented. Possible applications for morphological analysis of tissue structures are discussed.

A new restoration filter is proposed for the restoration of signals distorted by a random impulse response function and additive measurement noise. The filter is derived from the theory of constrained total least squares, an extension of total least squares to the case where linear constraints with additive random components are incorporated into the measurement model. This enables the incorporation of prior information about the original signal, expressed in the form of linear constraints such as smoothness and region of support. Furthermore, the filter does not require knowledge of the second-order statistics of the random impulse response function and noise. Simulation results are provided to demonstrate the effectiveness of the proposed filter.

Strictly speaking, all the physical sources are neither strictly coherent nor strictly incoherent. It is possible to exploit the coherence property of an incoherent source for complex amplitude processing. The properties that govern the coherent process are the spatial and the temporal coherence. If a desired spatial coherence must be known for a specific operation, it is possible to encode an extended source to obtain the desired spatial coherence. By simply dispersing the spectral content of an object in the Fourier domain, a desired temporal coherence can be obtained. The relationships between the source encoding and input object sampling to achieve the required spatial and temporal coherence are discussed. The use of source encoding is to relieve the basic constraint of an extended source. Signal sampling, on the other hand, is used to improve the ability of a broadband source. Since the coherence properties can be exploited from a conventional white light source, the proposed concept can be used for complex-amplitude polychromatic image processing. To confirm our discussion, examples and experimental demonstrations are provided.

A broken-character-mending algorithm is proposed to deal with broken characters. The algorithm can mend various kinds of broken characters if the number of missing pixels is smaller than the number of existing pixels in the mending masks. It also has no negative effects on the pixels that do not need mending. Mending masks of different sizes can be combined and the same mask can be applied several times to improve the mending result. The algorithm has been tested on some seriously broken characters, in which up to 50% of pixels are deleted randomly. The recognition process is based on statistical analysis combined with a shape recognition method. In our experiment, the recognition rate of the statistical method increased by about 7% after using the character-mending algorithm. The substitution rate decreased from 7.4 to 2.3% and the reliability increased from 91.9 to 97.6% after using the broken-character-mending algorithm.

New methods for lossy image compression based on generalized wavelet decompositions have been introduced recently. Unlike in the classical wavelet decomposition scheme, it is possible to use different scaling and wavelet functions at every scale by using nonstationary multiresolution analyses. This freedom in using different functions can be exploited for adaptive compression techniques. We extend this approach to arbitrary subbands (e.g., in a wavelet packet scheme), combine it with the best basis algorithm, and introduce efficient techniques for using these algorithms on parallel computers.

A novel shearing interferometer is described that uses an optimized phase grating as the shearing element. The method has a number of advantages over a conventional Michelson interferometer shearing device, including light efficiency, simplicity, and low cost. Quantitative fringe analysis is easily carried out by in-plane translation of the grating and the use of standard phase-shifting algorithms. The influence of higher diffraction orders on the noise in the measured phase distributions is discussed.

Theoretical and experimental methods of correlation processing of the speckle signals formed by a single-fiber multimode interferometer are investigated and demonstrated. These methods are based on (1) a photographic filter, (2) a standard computer, and (3) analog computing approaches. All of these methods enable the transformation modulation of the speckle pattern to be either optical or electrical signals, which linearly depend on correlation coefficients of reference and current speckle patterns. The functional dependence of the correlation coefficient on the value of the length of the interferometer is studied, enabling quantitative measurements of the length. Standard optical and electrical components are utilized, making the methods suitable for industrial use.

The higher order kinoform lens is a diffractive imaging lens for which the optical path length transitions between neighboring zones is an integral multiple of the design wavelength. Convenient expressions for diffraction efficiency, Seidel aberrations, and spherical aberrations of different orders are derived. It is observed that, when a p’th order kinoform lens with design wavelength ?0 is used with an illumination having bandwidth ?? around a midwavelength l, the key parameter in determining the diffraction efficiency and aberrational properties atm’th diffraction order is the ratio R = (m?/p?0).

A simple technique is devised to measure the angles of equilateral (60-deg) prisms, without using the expensive spectrometers, autocollimators, and angle gauges. The method can be extended to unpolished and opaque prisms made out of materials other than glass.

hybrid microlens/aperture mask assembly is fabricated, aligned and mounted on a CCD imager for an application in an imaging polarimeter. The microlens array is produced by direct laser writing in photoresist followed by electroforming and replication onto a glass substrate in registration with a slit aperture array on the reverse side. An alignment of the combined arrays to the CCD imager of better than 0.7 µm in lateral position and 0.005 deg rotation is achieved. Stray light of less than 1% was measured for the hybrid module. The optical microsystem satisfied the challenging requirements of the imaging polarimeter and the technique has applications in other areas of optical sensing, metrology and processing.

As introduced by Matheron (1975), granulometries depend on a single sizing parameter for each structuring element forming the filter. Size distributions resulting from these granulometries have been used to classify texture by using as features the moments of the resulting pattern spectra. The concept of granulometry is extended in such a way that each structuring element has its own sizing parameter and the size distribution is multivariate. Whereas with univariate granulometries the normalized size distribution (pattern spectrum) is easily shown to be a probability distribution function, this proposition is more difficult to show for multivariate granulometries. Its demonstration is the main theoretical result. The classical single-structuring-element granulometries appear as marginal size distributions and the single-parameter multiple-structuringelement granulometries result from setting all parameters equal in a multivariate granulometry. Because of the greatly expanded freedom in choosing parameters, multivariate granulometries can discriminate textures that are indistinguishable using single-parameter granulometries. Texture classification proceeds by taking either the Walsh or moment transform of the multivariate pattern spectrum, obtaining a reduced feature set by applying the Karhunen-Loe`ve transform to the Walsh or moment features, and classifying textures via a Gaussian maximumlikelihood classifier. For the disjoint multiprimitive random set model, multivariate granulometric moments are represented in terms of sizingdistribution moments and shown to be asymptotically normal. Formulas are given for their asymptotic mean and variance.

Considering the interface absorption in optical coatings, we propose a model to simulate interface absorption. Calculations are made and the temperature field of several kinds of thin film multilayers, including those of partial reflectivity, high-reflectivity, and antireflectivity coatings are analyzed. The interface absorption is found to greatly influence the temperature distribution within multilayer coatings and to weaken the laser damage resistance of the samples. The real-time results of the photothermal deflection technique for laser induced damage to samples supports the model.

A long-range surface plasmon resonance-based tunable optical filter is described. An attenuated total reflection device can be configured so that the reflected intensity of light is a maximum when the resonance condition is achieved. When the device is illuminated with polychromatic light at a fixed angle, the wavelength at which resonance is achieved shows a transmission maximum, with a full width at half maximum of less than 3 nm. By using an appropriate electro-optic material in the device, the wavelength of maximum transmission can be varied. Numerical results are presented.

The routing scheme and some permutation properties of a four-shuffle-exchange-based Omega network are discussed. The corresponding optical setup, which is composed of 2-D phase spatial light modulators and calcite plates, is proposed and demonstrated through mapping the inputs to a 2-D array. Instead of one shuffle-exchange followed by one switching operation as in ordinary Omega networks, in our presented system, the shuffle interconnection embraced in the switches is accomplished simply by varying the switching structure of each stage. For the proposed polarization-optical modules, the system is compact in structure, efficient in performance, and insensitive to the environment.

A fiber optic distributed sensing scheme used to monitor structural strain and deformation is presented. In the sensor system, a high-birefringent optical fiber is used as the sensing fiber, and the sensor units along the sensing fiber distribution are arrayed on a measured test structure. The structural deformation can be evaluated by detecting the polarization mode coupling effect in each sensor unit along the highbirefringent fiber. Interferometry and optical path scanning are used to determine the location and magnitude of the mode-coupling effects caused by structural strain or deformation.

A case study, written in a tutorial manner, is presented where a comprehensive computer simulation is developed to determine the driving factors contributing to spacecraft pointing accuracy and stability. Models for major system components are described. Among them are spacecraft bus, attitude controller, reaction wheel assembly, star-tracker unit, inertial reference unit, and gyro drift estimators (Kalman filter). The predicted spacecraft performance is analyzed for a variety of input commands and system disturbances. The primary deterministic inputs are the desired attitude angles and rate set points. The stochastic inputs include random torque disturbances acting on the spacecraft, random gyro bias noise, gyro random walk, and star-tracker noise. These inputs are varied over a wide range to determine their effects on pointing accuracy and stability. The results are presented in the form of trade-off curves designed to facilitate the proper selection of subsystems so that overall spacecraft pointing accuracy and stability requirements are met.

We described a low-cost, frequency-domain photon migration spectroscopy instrument by using in-phase and quadrature demodulation technique in a 140-MHz homodyne system. A time constant of 1 ms was obtained. A frequency-division multiplexing technique was used for multiposition or multiwavelength applications, such as for tissue oximetry. By conducting several experiments on tissue/blood models, we show that the optical properties of tissue can be determined with this system by either using multiple source-detector separations at accuracy better than 8% or using single source-detector separation. The accuracy with the latter method can be improved to be 10% or better by choosing a proper calibration sample. A frequency-sweep system (30 to 700 MHz) was also implemented; the phase and amplitude measured on a tissuelike solution at 780 nm agreed to their theoretical values within 5% and 10% accuracy, respectively.

There is a major interest in monitoring the fate of the earth’s ozone layer. A heterodyne spectrometer for the remote sensing of the vertical, integrated stratospheric ozone number density profile has been developed. A local oscillator ~LO! based on the tunable single-sideband CO2 laser with an external modulator capable of providing a sideband tuning range of 68 to 18 GHz on either side of the laser carrier.

When I first came across this book by C. Davis in a local bookstore, the thought that came to mind was ‘‘Is this yet another introductory book on lasers and electrooptics?’’ So when the book review editor of Optical Engineering, Bradley Duncan, asked me whether I would like to review this book I agreed with my earlier thought in the back of my mind. A quick glance through the book on receiving it reminded me of a similar book by Siegman @Lasers, University Science Books, Mill Valley, CA ~1986!#.