Laser requirements and limitations for VLSI optical interconnect networks employing computer-generated holograms are discussed from a system point of view. For architectures with a collimating lens at the laser and a collector lens at the detector, the restrictions on laser wave-length stability are typically ± 10 A (thus requiring the laser's temperature to be regulated to approximately ± 5°C to 10°C). Diffraction limitations are shown to restrict the density of interconnects to the 104/cm2 range from many architectures (in particular, "space variant" architectures), rather than the 107/cm2 to 108/cm2 range frequently cited for "space invariant" architectures. Architectures with a mixture of space variance and invariance can lead to intermediate densities. Some architectures require low threshold, high efficiency lasers, whereas others require very high output power with much less concern for threshold and efficiency. A network with 3000 point-to-point interconnects per square centimeter, each transmitting at a 500 Mbit rate with a 10-11 bit-error rate, is analyzed. The best system performance is obtained if wavelength stabilized high power (10 W) laser arrays are available. Monolithic integration is discussed, and the need for uniform and/or tunable emission wavelength may be the greatest challenge in this area.

Optical fiber testing of positive power cylindrical optics is shown to be bisensitive. This means that the resulting interferogram is twice as sensitive along the cylindrical (zero power) axis as along the orthogonal (power) direction. The analysis of such interferograms is discussed.

A novel interferometric approach for obtaining surface interferograms on Wolter-type optics is presented. A subaperture simulation experiment shows the data analysis steps required. A second, independent test basically confirms the simulation results. Splicing of the subaperture interferograms around the circumference is discussed.

We have used a grating microspectrofluorometer equipped with phase and fluorescence microscopy to study the intracellular localization and processing of fluorescent compounds that are not part of the natural cell chemistry (xenobiotics) and of fluorescent carcinogens. Our topographic and spectral observations, in conjunction with ultrastructural analysis, lead to the hypothesis of a dynamically organized multiorganelle complex involved in the cell's detoxification processes and possible protection of the cell's genetic apparatus. Our studies with quinacrine derivatives and benzo(a)pyrene suggest that the organelle complex involves the endoplasmic reticulum, the Golgi apparatus, the lysosomes, and the nuclear membrane, with a fine microchannel network interconnecting the different organelles. We have indications that there is not only a trapping of fluorescent carcinogens in the cytoplasmic components of the complex but also a possible "nuclear pump" (powered by the substrates of the hexose monophosphate shunt pathway) involved in ejection of xenobiotics from the nucleus. The instrumental performance allows the in situ pixel-by-pixel study of extranuclear and nuclear energy metabolism related to these processes in parallel to the blue and red spectral shifts associated with metabolites of fluorescent carcinogens. Recording of fluorescence emission spectra at different excitation wavelengths in human fibroblasts and rat liver cells allows the application of multivariate statistical methods to analyze multicomponent spectra. Elucidation of mechanisms involved in the organization and activity of the organelle complex is relevant to the interpretation of drug sensitivity or resistance and should result in better targeting of cancer chemotherapeutics and gene modifiers toward their expected sites of action.

A new, universal approach to reconstructing transform-coded images is proposed. The method views the images as a probability mass function (pmf), allowing the retained coefficients of a transform (Karhunen-Loeve, discrete cosine, slant, etc.) to be thought of as averages of the basis functions over the pmf. This sets the stage for reconstructing the original images by using the maximum entropy principle (MEP) and the minimum relative entropy principle (MREP) with the retained coefficients as constraints in the extremizations. A formulation combining the two methods is also proposed, resulting in a reconstruction algorithm that is fast, proceeding in an iterative way using the estimate from each coefficient as a prior pmf for the next one via the MREP. The proposed approaches are illustrated with images compressed by discrete cosine transform coding, and the results are compared with standard reconstruction using the inverse discrete cosine transform.

A new instrument for measuring the underwater spectral radiance distribution is described. This instrument, the electro-optic radiance distribu-tion camera system (RADS), is based on two electro-optic charge-injection device cameras with fisheye lenses and a filter changer for selection of the spectral region of interest. RADS allows a complete spectral radiance distribution to be measured in a short period of time and allows routine reduction to absolute radiometric data. Many other apparent optical properties such as vector irradiance, scalar irradiance, average cosine, and net irradiance can be derived from these radiance data. In this paper, the instrument is described, values of other optical properties derived from the data are presented, and the inherent optical property of absorption is calculated from the radiance distributions using Gershun's law.

Optical disk memories are assessed in simulated space radiation ionizing environments using cobalt-60 gamma rays and linear accelerator electrons. Total dose and dose rate testing of media including write-once and magneto-optic erasable technologies finds the media to be hard to over 1 Mrad (Si) of total dose over a range of dose rates. Optics, optoelectronics, and other critical technologies are considered, and hardening considerations are presented for total dose, displacement, and heavy particle radiation effects.

An optical multichannel analyzer was used to develop a reflectance radiometer for measurement of medical diagnostic samples. Sample areas were small, typically 5 mm x 5 mm. Spectral and temporal resolution of the reflectance measurements were 0.5 nm and 17 ms, respectively. Reflectance drifts were found to be less than 0.004 over 2 h with accuracy better than 0.012 compared with a reference method. Flexible instrument design allows use of many different illumination and detection geometries. Applications include performance evaluations of chemical formulations and readhead designs.

The development of comparative holographic moire interferometry is accelerated by the need for nondestructive testing. This paper describes a holographic moire technique for the detection of defects that is based on a comparison of the responses of two macroscopically identical specimens. At identical loading of the master and test objects, the moire fringes obtained are areas of equal differences in the mechanical responses, and they form closed curves around the defect. The schemes of additive and multiplicative moire are studied experimentally, and their advantages and disadvantages are discussed. Comparison of the suggested technique with conventional holographic interferometry shows its reliability for localizing defects. The comparative method is contactless and is especially appropriate for nondestructive quality assessment of mechanical parts.

We compare the performances of the binary joint transform correlator, the continuous phase-only matched filter correlator, the binary phase-only matched filter correlator, and the classic correlator for a limited set of patterns. Areas of comparison are the correlation peak, autocorrelation peak to sidelobe ratio, autocorrelation width, and discrimination sensitivity. In these areas, it is shown that the performance of the binary joint transform correlator is similar to the phase-only matched filter correlator.

Gaussian-apodized apertures are investigated for the purpose of reducing the diffraction background of a small-angle scatterometer. The farfield irradiance distributions of weakly truncated and untruncated Gaussian beams are compared. The envelope of diffraction ringing is shown to decrease proportionately with the level of truncation in the pupil. Spherical aberration and defocus are shown to have little effect on the higher-order diffraction rings of Gaussian-apodized apertures. A method is presented for determining the scattered irradiance level for a given bidirectional reflectance distribution function in relation to the peak irradiance of the point spread function. An example is provided that demonstrates that the small-angle diffraction background can be reduced by orders of magnitude as compared with a scatterometer with an unapodized pupil. Analysis of the point spread function is provided from 0 to 16 arcmin for an exit pupil diameter of 25.4 mm and A = 0.6328 Am. The numerical methods utilized to obtain these results are discussed.

Calculations indicate that the thermal stress resistance for diamond is significantly higher than for other materials, suggesting that diamond films may inhibit damage to optical components in laser systems. To assess this possibility we have begun to study laser-induced damage in diamond films. We have measured laser damage thresholds of free-standing diamond film windows, diamond films deposited on silicon substrates, and bare silicon substrate. Polycrystalline diamond films were deposited using a dc plasma-enhanced chemical vapor deposition process. As expected, the free-standing diamond films showed a high laser damage threshold. Melting or dielectric breakdown induced by laser radiation may be the damage mechanism. The film/substrate combination had a damage threshold lower than the calculated value, which is attributed to film stress and conditions of film deposition.

A measurement system has been developed capable of mea-suring reflected optical power as low as 0.0025% with a spot size diam-eter of 24 Am. One application for this system is the characterization of small-area photodetectors. The operation of the measurement system is simple, allowing the operator to quickly make multiple reflection measurements, and it does not require a darkroom. The measurement system merges a microscope, for visual alignment and focusing of the laser beam, with a lightwave component analyzer using modulation vec-tor error correction. A measurement comparison between the analyzer-based system and a power-meter-based system showed that each sys-tem can measure reflections as low as 0.0025%. However, the analyzer-based system offers the advantage of identifying the location and magnitude of system reflections. The system operates at a wavelength of 1310 nm.

Abstract. Optical recording characteristics of thin films of Set 100-xGex (where x is the weight percentage) are studied using an Ar+ laser at A = 488 nm. The variation of optical transmittance due to the laser illumination and the corresponding crystallization of the thin films are examined to provide an understanding of the variation of the microstructure in the thin films during the optical recording process. The laser-induced crystallization is associated with the growth of hexagonal selenium along one or several orientations. The diffraction efficiencies of real-time holographic gratings are measured during the writing process.

As we go through life we learn to overcome adversity, to bounce back from disappointment, to roll with the punches, to replace long-held beliefs with new ideas, etc., etc. But every now and then we come face-to-face with a hurdle that seems insurmountable; this just happened to me, and I am so disillusioned that I may never recover.

The Optics Source Book, one of the first five volumes in the Science Reference Series* taken from the McGraw-Hill Encyclopedia of Science and Technology, contains all the material from the encyclopedia relevant to optics, and it does cover the entire spectrum (so to speak).