This PDF file contains the front matter associated with SPIE Proceedings Volume 11032, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

A novel design of x-ray optical system wide field telescope for astrophysical rocket experiments is investigated and tested in real space flight experiment. The proposed system is based on 1D and 2D modules with Schmidt Lobster Eye (LE) configuration allowing usage of multi-foil mirrors arranged to Schmidt profile.

The recent progress in cube satellites platforms and related miniaturization allows scientific payloads to be considered for these mini satellites. In this paper, we present and discuss some possibilities for miniature astrophysical experiments onboard cube satellites with X-ray and UV optics. Albeit miniature, these payloads are capable to provide valuable scientific results at a low cost. Additional to technical and scientific aspects, there are also educational issues.

The paper summarizes the Rocket EXperiment (REX) Lobster Eye (LE) X-ray Telescope payload results. The experiment was performed by the PennState University with X-ray spectroscope on board a Water Recovery X-Ray Rocket (WRXR) launched on 4th April, 2018. The secondary payload was the REX LE X-ray Telescope. The REX LE X-ray telescope consists of two X-ray telescopes with one-dimensional (1D) and two-dimensional (2D) optics, a visible-light camera and an IR grid-eye. The primary structure consists of a metal housing for the optics and a carbon fiber baffle with the Timepix sensors mounted at the end. The observation data from the experiment are briefly presented and discussed.

Since its creation in 1996, Imagine Optic designed and manufactured high performance Shack-Hartmann wavefront (WF) sensors for many kinds of applications such as telescope alignment, laser characterization, optics qualification or adaptive optics, and for many different fields such as space optics, microscopy, high power lasers or lithography. Since 2003, Imagine Optic is actively developing EUV to X-ray Hartmann WF sensors for applications on metrology beams emitted by synchrotrons, free-electron lasers, plasma-based soft X-ray lasers and high harmonic generation. Our most recent developments include the realization of a EUV sensor adapted to strongly convergent or divergent beams having numerical aperture as high as 0.15, as well as the production of a hard X-ray sensor working above 10 keV, providing outstanding repeatability as good as 4 pm rms. Our sensors have demonstrated their high usefulness for the metrology of EUV to X-ray optics from single flat or curved mirrors to more complex optical systems (Schwarzschild, Kirkpatrick-Baez static or based on bender technology or with activators). In terms of optics qualification is a clear advantage of actually measuring the wavefront at-wavelength. Also, we show active Kirkpatrick-Baez alignment in few minutes using our WF sensor in both manual and automatic loops at the benefit of strong improvement of the beam focalization on the sample. Recently we started developing our own compact deformable grazing incidence mirror bender. We present a review of the developed sensors, as well as experimental demonstrations of their benefits for optical metrology of various EUV and X-ray optics.

Inspired by the recently successfully demonstrated Shack-Hartmann sensors for hard X-rays, we present a twodimensional compound refractive lens array (CRLA) with parabolic shapes for multimodal X-ray imaging. The promising structure was produced by two-photon polymerization using state-of-the-art 3D-Printer, which allows the manufacturing of sub-micrometer structures. The 2D parabolic microlens array with 12x12 spots was characterized by scanning electron microscopy and X-ray imaging. For an X-ray energy of 8.5 keV the average focal spot size is around 8 μm at a focal distance of 38.2±0.5 cm with a visibility of 0.72. As an example of a potential application for quantitative optics characterization a diamond refractive lens was investigated by multi-contrast imaging resulting in a 0.4 μrad differential phase resolution.

Nb-based Multilayer Laue Lens (MLL) shows high efficiency and great focusing ability at energy around 18keV theoretically. In this paper, to study the potential of Nb-based material combinations in nano-focusing, a series of Nbbased multilayers: Nb/Si, Nb/Al and Nb/Al(1%wtSi) are fabricated by using direct-current magnetron sputtering technology. Real-time stress measurement is utilized for stress analysis while the quality of multilayers is characterized by XRR and XRD. As a result, Nb presents a crystal state in the Nb/Si multilayer, and shows an asymmetric distribution at the interfaces. Both Nb films and Si films are in a strong compressive stress state, leading to a large total stress. Studies on the Nb/Al and Nb/Al(1%wtSi) multilayers show that both Al and Nb were crystalline under pure Ar sputtering conditions, resulting in large film interface width and poor film quality. The addition of 10% concentration of nitrogen in reactive sputtering can effectively suppress the crystallization of Al and change the crystalline state of Nb. However, the introduction of nitrogen greatly increased the compressive stress of Nb film, resulting in larger stress.

The setting up of experimental techniques, the synergic use of ellipsometry systems and synchrotron light sources are pivotal in the characterization and optimization of thin films devoted to EUV–VUV applications. The present manuscript will go through the research methods and the results obtained at CNR–IFN laboratories, by explaining the approaches adopted on the study of novel materials for the development of high throughputs EUV–VUV transmission filters, reflective coatings and phase retarders.

This paper presents a new method to model X-ray scattering on random rough surfaces. It combines the approaches we presented in two previous papers – PZ&LVS¹& PZ.² An actual rough surface is (incompletely) described by its Power Spectral Density (PSD). For a given PSD, model surfaces with the same roughness as the actual surface are constructed by preserving the PSD amplitudes and assigning a random phase to each spectral component. Rays representing the incident wave are reflected from the model surface and projected onto a flat plane, which is the first order approximation of the model surface, as outgoing rays and corrected for phase delays. The projected outgoing rays are then corrected for wave densities and redistributed onto an uniform grid where the model surface is constructed. The scattering is then calculated using the Fourier Transform of the resulting distribution. This method provides the exact solutions for scattering in all directions, without small angle approximation. It is generally applicable to any wave scatterings on random rough surfaces and is not limited to small scattering angles. Examples are given for the Chandra X-ray Observatory optics. This method is also useful for the future generation X-ray astronomy missions.

The surface error topography of optical aluminium surfaces after common manufacturing by single-point diamond turning meets the requirements for applications in the infrared spectral range. However, for short-wavelength applications in the (E)UV spectral range the requirements in the optical surface quality increase immensely. Reactive ion beam etching (RIBE) is a promising process route, which allows direct surface machining rather than the use of a NiP coating. Lowenergy ion beams driven by a reactive process control permit a roughness preservation up to 1 μm etching depth. The effect of RIBE machining on roughness features is evaluated suggesting a model scheme for smoothing of high-frequency features.

Single point diamond nanomachining allows to finish surfaces of some hard-to-machine brittle materials as for example germanium with high shape accuracy, low surface roughness and low subsurface damage. Quality of these surfaces is sufficient when infrared or visible light wavelengths are used. However, using hard X-ray wavelengths, additional polishing of the nanomachined surface is necessary. We are developing polishing methods of germanium surfaces produced by nanomachining, while optimizing nanomachining conditions such as the cutting speed, cutting depth or tool geometry in nanomachining centre. Micro Raman spectroscopy and atomic force microscopy (AFM) were used to study the effect of the cutting speed on the mode of the single point diamond machining (flycutting) of Ge(110) surface. Selected samples were also studied by the rocking curve imaging (RCI) at BM05 beam-line (ESRF), which serves as a test and development station for X-ray optical elements. The surface study indicates that the amorphous layer which originates by nanomachining in the sub-surface area of Ge (110) surface can be delaminated together with all structural imperfections within the chip using appropriate cutting conditions. Results of the study also show a dislocation-free single crystal lattice beneath the Ge (110) nanomachined surface, which demonstrates the potential of the applied method for the preparation of high quality surfaces for hard X-ray crystal optics.

We present characterization measurements of dark current signal at different temperatures and spectral sensitivity of cooled backside-illuminated EUV CCD matrices intended for future solar space missions, including projects ARKA and KORTES. The measurements have been conducted inside a vacuum chamber in the 125-250 Å spectral range with the use of tungsten laser-driven plasma as a source of EUV radiation. Applications of the EUV CCDs for contemporary and future space investigations of solar physics taking place in solar flares is being overviewed and discussed.

Solution-synthesized organic and inorganic semiconductors have recently received much attention for their applications in optoelectronic devices operating in the visible and near-infrared spectral regions. Here, we fabricate a photovoltaic detector architecture by use of hybrid metal halide perovskite film with selected cathode buffer layers. This device effectively converts the photons to current both in visible spectral range and in X rays. It is found that the device exhibits excellent performances with a transient response time as fast as 660 ns. In addition, we achieve an X-ray sensitivity up to 30 μC Gy^-1 cm^-2 for the hybrid perovskite photodetector. Thanks to the advantages of the device, such as the mechanical flexibility, low-cost and easy preparation, such photodetector based on solution-synthesized perovskite film is promising for photon detection in a wide spectral range.

Tomography is a 3-D imaging method, which allows producing 3-D images by image stacking and numerical refocusing, a spatially localized probing or by sample rotation. Usually, those methods are employed at visible range wavelengths of electromagnetic radiation. It is the simplest, most developed and most common approach since visible light is the part of electromagnetic radiation, which is the closest to humans. There are, however, certain limitations to the visible light methods, such as diffraction limit in the range of hundreds of nanometers, the incapability of direct imaging low-density objects, such as gasses, or the objects being completely opaque to the visible light radiation. Thus, the extension of those methods to the extreme ultraviolet (EUV) and soft X-ray (SXR) spectral ranges allows mitigating those problems. A few examples of such tomographic 3-D imaging experiments employing EUV and SXR compact, tabletop laser plasma sources will be presented and discussed.

In this work two kinds of reflective optical systems were used for creation and investigation of low temperature, photoionized plasmas. The plasmas were created in gases, irradiated with a focused beam of extreme ultraviolet (EUV) radiation. In experiments a laser-produced plasma source based on a 10 J/ 10 ns Nd:YAG laser system, and a double stream gas puff target, working with a 10 Hz repetition rate was used. The EUV radiation was focused using a ruthenium-plated, grazing incidence, ellipsoidal mirror with a high reflective coefficient in the wavelength range λ>10 nm. Different gases were injected into the vacuum chamber, perpendicularly to an optical axis of the irradiation system at the focal region, using an auxillary gas puff valve. Irradiation of the gases resulted in various excited states in atoms and ions. Spectra in EUV range were measured using a spectrometer (McPherson Model 251), equipped with a flat-field, 450 lines/mm toroidal grating. In all cases the most intense emission lines were assigned to singly or doubly charged ions, however, lines corresponding to ions with higher charge were also recorded. Apart from the time integrated spectral measurements also spectrally integrated but time-resolved measurements were performed, using a specially prepared detection system. The system was based on a paraboloidal collector and an EUV sensitive photodiode. In all cases the EUV emission time from the EUV-induced, low temperature plasmas was significantly longer comparing to the driving EUV pulse.

The precise characterization of flat substrates is quite challenging for X-ray optics in synchrotron and free electron lasers. The surface requirements for the substrates are on the order of magnitude of few nanometers and sub-nanometers, which is also a great challenge for optical fabrication and testing. As for precise metrology, the core problem is to characterize the surface figure with high accuracy. And the key is to separate the errors of the measurement instrument from the intrinsic figure error of the surface under test. In addition, the surface figure of thin optics is largely affected by surface deformations due to gravity. In the paper, we presented an approach to achieve absolute planarity measurement of a thin x-ray mirror substrate through an interferometric method. With a liquid-flat reference using dimethyl silicone oil, the power term of the surface flatness of the interferometer transmission flat is retrieved. By floating the mirror on a heavy, high density liquid, deflections introduced by gravity are essentially eliminated. The unconstrained, floated x-ray mirror is tested through several rotational and translational shears. The absolute figure error is then calculated by iterative algorithm with pixel-level spatial resolution. By the proposed approach, both the interferometer transmission flat error and gravity-induced error are calibrated. Thus the unconstrained flatness of the x-ray mirror can be obtained. The method is described in detail and a measurement example of an x-ray mirror is provided in the paper.

This work addresses the use of an electrostatic analyser as a method of resolving ion species and charge state in the plasma ablation plume. Passing charged particles between a pair of electrodes at a known voltage and correlating with charge to mass ratio Z/M and arrival time, allows one to perform ion spectroscopy. The time of flight showed a decrease in its value with the increase of the potential across the analyser plates. Higher plate voltage requires higher energy particles to pass through, thus higher speed and lower arrival time. LORENTZ 3D numerical software was used to model the trajectory of "test" ion beams and charged particles showed good agreement with simple modelling of the particles trajectory in an analytical description. The analysis of the experimental data was cross checked with the modelling of the analyser and the simulated LORENTZ 3D results and revealed the same general trends. Small differences were observed between the measured and simulated time of flight (< 1μs) which can be attributed to either the electronics used which has to respond on the order of nanoseconds or the simulated data are imperfect models for physical reality and can be reliable only if they demonstrate agreement with experimental results. This work presents also evidence on successfully resolving 15 of the distinct charged particle species (proton and ions released from the VHS tape used as the primary target in this work) emitted from the laser plasma.

In this work, we present a novel construction of two experimental devices dedicated to producing laser-matter interaction targets for laser-produced plasma experiments and some results of first experiments concerning target characterization and interaction of developed targets with femtosecond pulses. Both devices are being developed in the Institute of Optoelectronics as a result of research in laser-plasma experiments based on pulsed gas targets. The first device, pulsed aerosol source, based on gas puff aerosol target formed in a vacuum, is a combination of pulsed gas target and ultrasonic generation of an aerosol from liquids. Production of aerosol in our devices is being done directly in the vacuum chamber, without using high gas pressure, supersonic nozzles or any heating elements. Depending on the liquid used, the parameters of the aerosol target can be easily changed. The second device, gas cluster target, is based on our previous construction - double stream gas puff target and the effect of pre-cooling the target gases. In this case, we are able to produce double stream gas-cluster target from atomic and molecular gases. Presented experimental devices can be used for producing new, highly efficient laser plasma sources of extreme ultraviolet (EUV) and soft X-ray (SXR) radiation and also for EUV/SXR spectroscopy experiments.

We present a brief review of radiography technique (shadowgraphy) and its extension to tomography. We used both techniques to characterize i.e. multi-jet gas puff target for different gases with a variable number of jets for various applications. The characterization measurements have been performed with the use of EUV shadowgraphy at 13.5 nm wavelength. Pulses of the EUV radiation were produced with a laser plasma EUV source based on a double-stream gas puff target. The shadowgrams of the characterized gas puff targets were registered using a back-illuminated CCD camera, sensitive to the EUV radiation. The gas density maps were calculated based on 2D transmission map and an atomic photoabsorption cross-section. To obtain 3D tomography reconstruction of multi-jet gas puff target we acquired projections at different viewing angles and performed the reconstruction numerically. This unique technique based on a compact laser-produced plasma source allows imaging 2D and 3D objects having a density 3 orders of magnitude smaller than the density of water.

A desktop tomography system, based on laser-interaction with a gas puff target, which results in efficient plasma formation emitting in the soft X-ray (SXR, λ = 0.1 - 10 nm) region, was developed at IOE-WAT (Warsaw, Poland). The system, coupled with an ellipsoidal condenser and a Fresnel zone-plate and working in the “water window” spectral range (λ = 2.3 - 4.4 nm) at the quasi-monochromatic He-like nitrogen spectral line (λ=2.88nm), allows acquiring images approaching a resolution of few microns. The development of such setup offers the possibility to obtain a reconstruction of three-dimensional images in a laboratory environment, without the involvement of large “photon facilities”. Details about the system and its optimization as well as some imaged samples will be presented and discussed.

With the rapid development of microelectronics, nanotechnology and integrated design concept, the trend of satellite miniaturization is becoming more and more obvious, and the high resolution of small satellites is enhanced, and the capability of remote sensing is the forward position to promote space exploration and technological innovation. For the telephoto optical system, the influence of the spatial thermal environment changes and the change of the gravity field before and after the launch will change the focal length of the optical system, resulting in blurred image, so the need for focusing the focus parts to focus. According to the overall technical requirements of the satellite, a small-scale super-resolution spatial camera system based on the traditional Cass-grain optical system is designed. The modal, sinusoidal vibration and random vibration of the system are simulated by mechanical simulation software. The results shows that the mechanical properties of the system are good. The load has been successfully launched and a good image effect has been achieved.

To bring global optimization capability on optical design of a focusing objective in soft X-ray region, we describe novel design approach by combining analytical and numerical methods based on geometric optics. We assume two-spherical mirror objective of glazing-incidence configuration. First, relationship between system layout parameters, i.e., radii of curvatures and mirror separations, and focus length is derived with paraxial approximation, to describe all feasible mirror layouts with constant focal length. Then, focusing property of the mirror objectives are computed by applying numerical raytracing method, to seek practical optical designs with low aberrations. As design examples, the proposed method is applied to a two-spherical-mirror objective for one-dimensional focusing of soft X-ray high harmonics. We successfully find three kinds of practical designs with low aberration. The calculation results show that we can expect small spot size close to 100 nm on the focal plane, for the case that the objective has moderate focal length (f = 100 mm) and numerical aperture (NA = 0.02). These results indicate that the proposed approach is capable of global optimization of the mirror objective with glazing-incidence configuration.

Studies of polarization-sensitive, such as circular dichroism spectroscopy, spin-polarized photoelectron spectroscopy and spectroscopic ellipsometry, accurate evaluation of the polarization state of the radiation is clearly crucial, which requires polarization optical elements, such as polarizer, analyzer and phase retarder. In EUV and soft x-ray region, the closeness of the real part of the refractive index to unity, coupled with high absorption, makes the realization of polarizers such like birefringence and dichroic polarizers impossible. Periodical multilayers are commonly used in polarization study working at the quasi-Brewster angle due to their interference structures. In order to expand the narrow spectral bandwidth of the periodic multilayer, the aperiodic multilayer and lateral gradual multilayer polarizers including reflective analyzers and transmission phase retarders are utilized. In this work, we demonstrate a series of periodic, aperiodic and lateral gradual broadband multilayer polarizers with the material combinations of Mo/Si, Mo/Y, Mo/B₄C, Cr/C, Cr/Sc, Cr/Ti, Cr/V and W/B₄C. Different types of multilayer polarizers correspond to different energy ranges, covering the energy range of 50- 1000eV, including “water window” and the L absorption edges of Fe, Co and Ni. Polarization measurements are performed at National Synchrotron Radiation Laboratory in Hefei and Beijing Synchrotron Radiation Facility. Some of the polarizers we have developed are applied to the polarization measurements of Beam-line 3W1B of Beijing Synchrotron Radiation Facility.

Aperiodic multilayer structure and lateral gradual multilayer structure can be used to expand spectral bandwidth of multilayer polarizers. To extend application of polarization in EUV and X-ray region, two-dimensional graded multilayer structure is utilized, which is a kind of mirror with gradient period along two lateral directions and can be widely used in synchrotron radiation and polarization studies of magnetic materials. In this paper, a [Mo/Si]25 laterally graded multilayer was deposited on a 40 mm×40 mm large silicon substrate by magnetron sputtering and it was measured by grazing incidence X-ray reflection. The d-spacing gradient along X direction, from 0.0528 nm/mm to 0.116 nm/mm, was achieved by controlling the velocity of the substrate as it passes through the flux. A shaped mask controlled the d-spacing gradient in the Y-axis perpendicular to substrate translation, from 0.12 nm/mm to 0.18 nm/mm. The dspacing was 6.39 nm for the minimum and 15.65 nm for the maximum. This method is capable to prepare twodimensional laterally graded multilayer mirror in EUV and X-ray regions.

In this contribution, we compare the performance of Hartmann masks and inverted Hartmann masks of different periods for phase-sensitive X-ray imaging. The Hartmann masks were gold meshes and the inverted Hartmann masks were arrays of gold pillars, both manufactured by UV lithography and gold electroforming on low-absorbing graphite substrates. We asses masks performance by comparing the visibility and homogeneity of the periodic patterns. Manufactured customized masks exhibit clear periodic patterns and demonstrate visibility values from 30 % to 50 % depending on the setup configuration. Finally, we show the phase contrast imaging with an angular resolution of 1.5 μm and demonstrate that images obtained with an inverted Hartmann mask have superior quality.

The optical properties of thick silicon dioxide on silicon substrate SiO₂/Si were fully investigated at the hydrogen Lyman– alpha spectral line. In this case, it was observed that the reflectance measurements are not enough to determine reliable values of the optical constants, but a full polarimetric investigation is required. Thus, the optical constants were determined together with the phase retarder properties by combining EUV reflective ellipsometry and reflectometry. The experimental system used for the measurements is a reflectometer optimized for VUV–EUV spectral range and equipped with a linear rotating polarizer used as an analyzer. The results show the potential of the approach, suitable for cases in which the determination of the ellipsometric parameters, ratio ρ, and phase shift φ, is required for a complete study of the optical and structural properties of the samples. Moreover, it was found that SiO₂ behaves as a retarder by introducing a phase difference between the s-and p- polarization components of the incoming light. The phase shift ranges from 18° to 160° depending on the incidence angle. The method, the experimental measurements, the analysis and the results are discussed thereafter.

Recently developed silicon carbide (SiC) detectors have been employed to study pulsed laser plasmas produced by irradiation of a double-stream gas puff target with nanosecond laser pulses. The plasma emitted by a gas-puff target source in the soft X-ray (SXR, λ = 0.1 - 10 nm) and extreme ultraviolet (EUV, λ = 10 - 120 nm) ranges was monitored with silicon carbide (SiC) detectors and compared with a commercial, calibrated silicon (Si) photodiode (AXUV-HS1). Different filters have been used to select the emission in different wavelength ranges from the broad-band emission of the plasma. This work shows the applicability of SiC detectors to measure the SXR and EUV ns pulses from the plasma, useful for monitoring and optimizing the gas-puff laser-plasma sources developed at IOE-MUT, in Warsaw (Poland). Some aspects relative to the plasma stability as well as characterization of the plasma source (i.e. the overall evaluation of the signal and the time trace profile) will be presented and discussed.

Faraday rotation is a magneto-optical phenomenon defined as the rotation of the polarization plane of light passing through a transparent isotropic sample in the presence of an external longitudinal magnetic field that causes an induced difference between the refractive indices for right and left circularly polarized light inside the sample. In this paper, we present the details of a newly developed ultra-sensitive Faraday rotation device consisting of a GaN-based light emitting diode as the light source of wavelength range 400 – 480 nm. Two linear polarizers are used; the first polarizer is placed before the quartz sample cell to set a reference polarization angle while the other polarizer is connected to a stepper motor which is configured to change the polarization angle of the light beam exiting the cell. A ring permanent magnet is coaxially fitted around the quartz cell and is employed to generate a strong external magnetic field of ~ 1 Tesla. The detection system consists of a sensitive and fast light detector coupled with an electronic circuit board which is configured to record the finest Faraday rotation angle in the polarization direction of the transmitted light relative to the reference polarizer. In addition to the experimental details, the modes of operation and sensitivity of the device will be also presented.

The study of biological objects using a light microscope is one of the main methods of diagnostic practice in many areas of natural science. Most modern methods of researching objects using a light microscope include preliminary preparation of objects. However, in this case it is impossible to achieve a high degree of reliability of information about the object under study.

In this paper, by using the finite-difference time-domain method we study the formation of optical vortices by amplitude spiral zone plates with the topological charge of 2 μm, the diameter of 8 μm and the focal length of 0.532 μm made in 0.1 μm metal film. Silver and gold are proposed as a material of relief. The Gaussian beams at the wavelength of 0.532 μm with left and right circularly polarization are considered as incident light. Analysis of amplitude, phase, and intensity for each electric field component shows the presence of phase singularities which produce vortex field with complex structure.

In this paper amplitude Fresnel zone plates with metal relief on silica glass is investigated. Simulation by frequencydependent finite-difference time domain method shows that all proposed designs of amplitude lenses can produce focal spots whose transversal size could overcome the diffraction limit (full width at half maximum of intensity is 0.38 – 0.46 of wavelength) and in several cases amplitude zone plates give tighter focal spot (full width at half maximum of intensity is 0.38 of wavelength) than phase zone plate.

Using simplified two-dimensional finite element method (FEM) modeling we study such structures where the triangular dielectric prism is used for producing nano-jets. The soda-lime glass (n=1.46), polystyrene (n=1.56), polyester (n=1.59), barium titanate (n=1.8) is considered as material of the prism. The width of the triangular prism base is fixed at 60 um while the height is varied to obtain optimal focal spot parameters such as maximum intensity, full width and depth at half-maximum of intensity. The linear polarized Gaussian beam with a wavelength of 4 um and the waist width of 80 um is taken as the input radiation. All numerical simulations were carried out by COMSOL Multiphysics which used irregular grids with variable steps for FEM. The small step equal to 0.1 um was used in regions which are close to the interface between two media, while the other area is described by grids with steps of 0.2 um. Comparison of simulation results for dielectric triangular prism and simulation results for dielectric circular cylinder shows that prism can produce the narrower focal spot. It can be also noticed that there are resonance modes similar to the whispering gallery modes are formed inside the triangular dielectric prism. The influence of these modes on light focusing is also studied.

Indium tin oxide (ITO) thin films have been widely used in displays such as liquid crystal displays and touch panels because of their favorable electrical conductivity and optical transparency. The surface shape and thickness of ITO thin films must be precisely measured to improve their reliability and performance. Conventional measurement techniques take single point measurements and require expensive systems. In this paper, we measure the surface shape of an ITO thin film on top of a transparent plate using wavelength-tuning Fizeau interferometry. The surface shape was determined by compensating for the phase error introduced by optical interference from the thin film, which was calculated using the phase and amplitude distributions measured by wavelength-tuning. The proposed measurement method achieved noncontact, large-aperture, and precise measurements of transparent thin films. The surface shape of the sample was experimentally measured to an accuracy of 40 nm, mainly limited by the accuracy of the reference surface of 30 nm.

The key characteristic of any acousto-optical device, which describes its angular and spectral selectivity, is a transfer function, which depends on the light wavelength, acoustic power, configuration and length of acousto-optic interaction, refractive indices of the media, etc. The shape of transfer functions was earlier analyzed qualitatively for the most commonly used configurations and several topological types of transfer function were described in uniaxial acoustooptical crystals. For spectral imaging applications, however, this analysis is not sufficient and the detailed quantitative investigation is necessary for any particular diffraction geometry. In this study, we first time demonstrate results of accurate calculation of the transfer function for any incident light direction and any reasonable ultrasound wave angle with account of crystal geometry and parameters. All the topographical types of transfer function are described. These results are important for the development of imaging acousto-optical tunable filters with aberrations correction or with required homogeneity of the transmitted image intensity.