A highly efficient EUV spectrograph is designed for high-resolution spectroscopic observation. The spectrograph is designed for point source astronomy in a 40-120 nm bandpass and is to be ORFEUS (Orbiting Retrievable Far and Extreme Ultraviolet Spectrometer), scheduled for launch as the first payload of a German space platform Astro-SPAS (Astronomy Shuttle Pallet Satellite). The design uses spherical varied line-space (SVLS) grating to minimize astigmatism, coma, and spherical aberration. The effectiveness and practical feasibility of the design is proved by an SVLS grating for visible use. The image focusing properties of the SVLS grating for ORFEUS are compared to those with toroidal uniform line-space (TULS) design. The SVLS design is superior to the TULS, theoretically in resolution and image concentration, but also practically with not only fabrication ease. Four SVLS gratings with nominal groove densities of 6000, 4550, 3450, and 2616 gr./mm, and a 200 mm x 200 mm ruled area have been ruled using a numerically controlled ruling engine for use in ORFEUS.

The association of a photoresist grating and a prism usually called 'grism' by astronomers is studied in detail from the efficiency point of vue with the Differential Theory of Diffraction Gratings. Starting from the grism equation, the blaze properties of echelette transmission gratings are studied in visible region as functions of blaze angle and groove spacing. The influence of incidence is considered. The asymptotic case of echelle is studied too. A special solution for perfect blazing is given.

A model of liquid crystal orientation under the influence of an arbitrary potential pattern; and therefore, the phase exhibited by the liquid crystal device is presented. The model consists of a two-step iterative solution: (1) the potential distribution for a pre-set liquid crystal tilt and orientation is solved, (2) using this solution, a small angle approximation of Frank's equation, with additional electrical energy term is minimized with respect to new angles of tilt and orientation. These new angles are then used as the pre-set angles in the next iteration. Both steps are implemented with finite element methods.

We first outline an approximate method to study the diffraction by monoperiodic and biperiodic absorbing structures whose thickness is small compared with the incident wavelength. Then the numerical implementation is discussed.

The recent development of highly efficient and highly transparent holographic materials such as dichromated gelatin and various types of photopolymers has stimulated several attractive wavelength dispersive and wavelength filtering applications for volume holographic optical elements in both reflection and transmission geometries. Within the class of uniform volume periodic holographic structures, we recognize dispersion-free Lippmann filters and dispersive slanted holographic structures (gratings). While the former is competitive with dielectric multilayers, the latter is comparable to surface-relief holographic and nonholographic gratings. Dispersion-free Lippmann filters are commonly represented by Raman filters, wavelength- selective IR mirrors, solar-control windows, XUV mirrors, and eye-protection rugate filters. On the other hand, dispersive slanted volume holographic structures have been most successful in the Littrow configuration and as quasi-Lippmann gratings used in WDM data links, as well as within holoplanar interconnects and TIR couplers for 3D optoelectronic processor. This paper presents recent developments of volume holographic optical elements in two areas of interest: holographic filters and gratings.

Identification of dimensional parameters of an arbitrarily shaped grating using scatter characteristics is presented. A rigorous diffraction model is used to predict the scatter from a known grating structure, and utilizing this information we perform the inverse problem of predicting line shape from a measurement of the scatter.

Comparisons between Electromagnetic Theory predictions and measurements are presented for four types of gratings supporting a very high number of diffracted orders. The first type consists of gold coated gratings used in soft X-ray region. The second one is a multilayer grating designed to have a broad reflection band around 0.6 nm wavelength. The third type is a transmission echelle used in the visible and the fourth, an echelette grating for use in the X-ray region. Good agreement between theory and experiment was found in all cases. In the latter case, the groove shape was far from ideal but using the real measured profile in the efficiency calculation good agreement was found even in this extreme situation.

Rayleigh-Fano theory has been extended for the purpose of calculating the polarization anomaly of a grating having shallow grooves and finite conductivity. Simple analytic formulas are derived for predicting the position and the appearance of the anomalies. Phenomenological explanations are given to the origin of the anomalies. The validity of our analysis is examined by comparing computed degree of polarization with experimental data obtained in the visible region for Al-, Ag-, and Au-coated blazed gratings.

We report on the numerical aspects of the `method of fictitious sources' which, for us, appears as a particular case of a more general method we have called `the synthesis method' in previous theoretical papers. As an illustration, the method is applied to different kinds of echelette, sinusoidal and wire gratings.

We describe an integral approach to the rigorous solution of Maxwell's equations for diffraction from a biperiodic grating having arbitrary profile and periodicity. Emphasis is placed on the implementation of solutions and is addressed to the engineering community. The method described is amenable to mathematical convergence analysis. A numerical example is given which indicates convergence of solutions.

Among the various rigorous electromagnetic methods previously developed in order to compute and optimize grating efficiencies, Differential Formalism turns out to be the only one capable of dealing with reflection gratings in the x ray region. Not only can the method tackle bare gratings, but it is generalized in order to handle a multilayer stack deposited on top of a blazed grating. This can be a classical stack of equal pairs of dielectric and absorber, but the method can also deal with an arbitrary number of layers with arbitrary thicknesses varying from bottom to top. Contrary to the classical stacks which give high efficiencies in a narrow range of incidence or wavelength, the second type of stacks can be optimized in order to obtain a broadband efficiency curve. It is shown that with the grazing incidence angles used in the x ray domain the reflection of the multilayer structure cannot be considered to be decoupled from the diffraction of the groove profile. Consequently, a full electromagnetic study has to be carried out for the entire device in order to get reliable results.

Experimental results on multiline holographic notch filters in Du Pont photopolymer by multiplexing are reported. Two-line filters have achieved peak optical densities greater than 2 at each wavelength. A brief review of the theory is given. Experimental results are compared with theoretical predictions.

The purpose of this paper is to use a well established electromagnetic theory of gratings to analyze the effects of total internal reflection beam geometry, sample modulation, and tip position upon the signal received by the probe tip of a photon scanning tunneling microscope as it scans a particular sample.

A perturbation method for studying the bistable behavior of a prism or grating coupler filled with a Kerr nonlinear medium is developed. A field representation limited to its first space harmonic already gives a satisfactory agreement with the much more complicated rigorous differential method. A better accuracy can be obtained by the use of the two first space harmonics. We then obtain an almost perfect agreement with rigorous theory, always with much lower computation times. All the relevant parameters useful to characterize the bistable behavior are given by this perturbation method.

The limit of resolution for the planar varied line-space grating in a converging beam can be found by analyses of the optical path errors. The errors may be canceled by slight deviations of the planar substrate surface. The cancellation of the path errors leads to a markedly improved spectral resolution. The surface figure for an improved resolution deviated planar varied line-space grating spectrograph is shown. Ray-tracing of this improved spectrograph shows substantial gains in spectral performance.

The electromagnetic field distribution in the profiled metal-semiconductor and metal-oxide- metal systems was computed. When the reciprocal grating vector equals the difference of wavevectors of the surface modes at the two interfaces of the metal film, the effective resonant tunneling of the electromagnetic field through the metal film is possible. This may substantially increase the efficiency of the mentioned structures, used as selective photodetectors or light-emitting devices.

We show measurements of interorder scattered light from various grating surfaces. The measurements compare holographic and ruled gratings for in-plane and out-of-plane conditions at 254 nm and 633 nm.

Electromagnetic modes may be excited by photons using grating coupling to provide the necessary extra momentum. Rotation of the grating so that the grooves are no longer perpendicular to the plane of incidence (conical diffraction) breaks the symmetry of the system and introduces polarization conversion. This conversion is strongly enhanced when a mode is excited. Reflectivity data are presented showing polarization enhancement by the excitation of surface plasmon polaritons (SPPs), long range surface plasmon polaritons, and resonant guided modes on surface modulated gratings. The dependence of this conversion on angle of incidence, azimuthal angle, and groove depth has been studied in detail. When the grooves are at 45 degree(s) to the plane of incidence, maximum conversion is recorded for the SPP. However, for guided modes the maximum conversion occurs at angles other than 45 degree(s). The conversion has been seen to rise monotonically with groove depth and efficiencies of over 50% are easily obtained via SPPs and guided modes. Theoretical comparisons with data are made using a rigorous differential method applicable for conical diffraction. This formulation uses a coordinate transformation between the grating surface and a planar system. The comparison between data and theory is very good and further theoretical modeling predicts that conversion efficiencies can approach 100% for appropriate circumstances.

We analyze the reflection spectrum of multiple chirped gratings using coupled-mode theory. We also design filters with desired reflection spectrum by adjusting the parameters of multiple chirped gratings.

We look at the behavior of three different plane gratings in spectral regions where they exhibit anomalous efficiency behavior. Circumstances are presented where anomalies are either shifted, reduced, or enhanced. The gratings chosen are 1200 grooves per mm blazed at 26.75 degree(s), 1200 grooves per mm holographic sinusoidal with 18% modulation, and an 1800 groove per mm holographic `self blazed' at 13 degree(s).

Intensity-to-phase modulation can be used for phase coding of an input image, instead of the commonly employed halftone technique. When placed at the entrance of a 2 f coherent system with the selected diffraction order, the phase-coded image shows nonlinear behavior. No special screen design is necessary and a simple Ronchi-type or sinusoidal gratings can be used. Using DCG, we attained an input dynamic range of three order of magnitude, a significant improvement over previous work. A multipeak transfer function was obtained by photoresist as a recording media, which is useful for equidensitometry. Generally, the phase-coding for the nonlinear optical processor is more light efficient and allows a real time implementation with an erasable photopolymer material.

Diffractive optical elements are becoming a standard optical design element. However, their fundamental performance is most often modeled using scalar theories which leads to optimistic performance levels. In this paper, scalar approximations are compared to rigorous electromagnetic solutions for various diffractive optical elements.

A novel method is developed to fabricate varied line-space corrugations to improve the characteristics of distributed feedback (DFB) semiconductor lasers. Mechanically ruled grating patterns are transferred photolithographically to the surface of a semiconductor substrate by a contact mask aliner using the ultraviolet radiation of a He-Cd laser as a light source. The resultant varied line-space corrugation, like (lambda) /4-shift and corrugation-pitch modulation, improves the characteristics of distributed feedback lasers

We present a simplified modal analysis of a Kerr-type grating coupler that rigorously takes into account the groove depth of the grating. These nonlinear grating couplers exhibit optical bistability. A comparison between the bistable loops obtained from this simplified method and a previously published rigorous method is performed.

Reflection microlenses for oblique incidence can be flexibly used without a beam splitter, and also could be key devices in planar optics and optical interconnections with a zigzag optical path within the substrate. The functions of the electron-beam writing system that we developed have been expanded so that the diffraction-limited microlenses for oblique incidence can be fabricated. It is demonstrated that electron-beam written microlenses including rectangular- apertured lens array exhibit the diffraction-limited focusing characteristics with 78% high efficiency at a large oblique angle of 30 degree(s).

Recent trends in laser application systems such as optical information systems, optical network systems, and optical measurement systems have increased the need for small size, light weight, low cost, and mass producibility. Advantages of a micro grating device in laser application systems are high integration capability, design flexibility, and mass producibility. In particular, several approaches have been presented for the application of micro grating devices to optical heads for CD players. However, few studies have been made to apply to MO disk heads. This is because it is difficult to realize polarization separation. In this paper, we propose a grating beam splitting polarizer based on form birefringence, which has several applications to MO disk heads including polarization separation, optical path separation, and signal detections. The polarization separation characteristics as a basic operation of the grating beam splitting polarization have been confirmed. The resultant extinction ratios obtained were -7 dB for the ordinary light and -6 dB for extraordinary light.

A trial design and fabrication of a multiple beam accessor using micro-Fresnel zone plate elements are reported. An element is composed of two orthogonal linear zone plate arrays with line width changing from 1.0 micrometers to 1.6 micrometers . The focusing characteristics are examined at 0.83 micrometers in wavelength using a laser diode. The feasibility of applying it to a high speed optoelectronic integrated circuit and a parallel optoelectronic computing scheme is discussed.

An interferometer consisting of a reflective diffraction grating, a beam splitter, and an incandescent lamp can be used for fine displacement measurements. For analyzing how grating ruling errors influence the interferometer's precision, the paper presents an error transfer function. The transfer function disperses the accidental ruling errors so the equi-spaced interference fringes can get by the interferometer. The fringe signal equi-spaced errors are about 10 -2 nm in theory.

In this paper, the equations and the contrast of moire fringes, the sensitivity, and the maximum distance allowed between the two gratings in moire deflectometry (MD) are studied in detail on the basis of wave optics. In the analysis the affection of the transfer function for the propagation of a wavefield and the object-image conjugation are considered.

Self-imaging phenomena still exist when a plane grating is illuminated by a monochromatic arbitrary wavefield. The surfaces of the self images are curved, the curvature is determined by the second partial derivatives of wavefront functions. The larger the distance between the grating and a self image the more curved the surface is. The fringe density in self images is affected by the first partial derivatives of wavefront functions. Wavefront functions must satisfy some conditions so that self-images appear.

A new method of 3-D shape measurement by moire technique is presented. An interferometer and computer were used instead of gratings to obtain moire contour. The principle of it is theoretically analyzed in detail. In order to obtain moire contour without unwanted patterns, we propose a method of obtaining moire contour by XOR logic using a computer. Experimental results are given.

With the recent advances of MBE and MOCITD techniques, it has been possible to grow semiconductor superlattices (SL's) composed of alterior e layers of two different degenerate materials with controlled thickness. The SL has found wide applicants in many new device structures, such as photodetectors, avalanche photo-diodes, tunneling devices, transistors, light-emitters etc. In addition to the usual Ill-V SL' s having Kane type energy bands, the SL's with more complex structures such as II...VI, PbPe/ PbSnTe, strained layer and IIgTe/CdTe SL' s have been proposed with the assumption that the interfaces between the layers are sharply defined with zero thicknesses, so as to be devoid of any interface effect. As the potential form changes from a well to a barrier, an intermediate potential region exists for the carriers. Thus the influence of the finite thickness of the interface on the electron dispersion relation becomes iniportant. It appears from the literature that the photo-emission from small gap SL's with graded interface has yet to be reported under quantizing magnetic field. In this paper, an attempt is made for the first time to investigate the photo emission from such heterostructures and compare the same with the bulk specimens of the constituent materials by formulating the respective magneto-dispersion relations. It is found that the photoemission exhibits oscillatory dependence with inverse quantizing magnetic field and the electron concentration respectively in all the cases. The oscillations in HgPe/CdTe superlattices show up much more significantly as compared to other systems even in the presence of broadening. In addition, the well-known expressions for the bulk specimens of non-degenerate parabolic materials have also been derived as special cases from our generalized expressions.