Mirror objectives with variable focal length

We consider some issues involved in constructing a mirror system with a discrete variable focal length. We propose a procedure for designing two-mirror pancratic (zoom) systems with fixed image plane. In constructing the optimal layouts, we studied a basic two-mirror system to achieve minimum spherical aberration. We present the calculated design characteristics of an objective consisting of two spherical mirrors and providing a three-fold variation in focal length. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 453–459, May–June, 2009.     

An integrated optical system for the vacuum ultraviolet region

We use a 0.5 m Seya-Namioka monochromator and two gold plated cylindrical mirrors to set up an optical system which produces a collimated beam of plane polarized, monochromatic radiation in the vacuum ultraviolet region. The two mirrors compensate for the astigmatism of the Seya-Namioka monochromator, thereby increasing the spectral resolution drastically. The degree of linear polarization is about 0.97–1.00 in the spectral region of 6–11.5 eV.     

Study of the reflectivity in the XUV domain of normal-incidence multilayer mirrors

Summary The development of multilayer optics has profound implications for soft-X-ray/UV astronomy, since it allows to extend the use of normal-incidence telescopes to cover the XUV region where lines are formed at greatly different temperatures (10⁵–10⁷ K). A multilayer mirror consists of alternating thin layers of suitable materials deposited on a substrate and its performance depends not only on the optical properties of the materials but also on the design of the multilayer. In this study we have computed the reflectivity of multilayer mirrors to select both the materials and the multilayers design to achieve the best performance in the wavelength range from 30 to 350 ?. Our calculations show that high theoretical reflectivities, from 0.2 to 0.8 and relatively narrow bandpasses, from ∼ 1? to ∼30 ?, can be obtained, in the wavelength range from 30 to 350 ?, by a suitable choice of the materials and of the multilayer design.     

A multimode model of a waveguide laser cavity with mirrors of arbitrary radius of curvature

A multimode model is developed to determine optical losses in a waveguide laser cavity of cylindrical symmetry with mirrors of arbitrary radius of curvature. Within the framework of the model, it is possible to vary the parameters of the resonator: waveguide length, distance between the waveguide and mirrors, radius of curvature of the mirrors in a wide range taking account of mutual conversion of up to 10 waveguide modes and 20 modes of free space. The model was applied successfully to determine the optimal geometry of a semiconfocal cavity. A. N. Sevchenko Scientific-Research Institute of Physical Problems, 7 Kurchatov Str., Minsk, 220064, Belarus; e-mail: v.saetchnikov@rfe.bsu.unibel.by. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 6, pp. 779–783, November–December, 1999.     

Grazing incidence systems with multiple reflections

The theory of turning soft x-ray SXR radiation beams by means of concave surfaces through multiple reflections (the “whispering-gallery” effect) is developed. It is demonstrated that concave mirrors are capable of turning an SXR beam by an arbitrary angle determined by their aperture angle. The reflectivities are of the same order of magnitude as those of multilayer mirrors (20–80% at a turn by 90°). The turning mirrors feature a wide spectral transmission band (Δλ ∼ λ). The potentialities of concave mirrors and hollow cylindrical waveguides with respect to concentration and collimation of SXR radiation are considered. The requirements imposed on the smoothness of the reflecting surfaces are obtained and the optimal (as to their optical properties) materials are chosen for their fabrication. The theoretical results are compared to experimental data. Translated from Trudy Fizicheskogo Instituta im. P. N. Lebedeva (Proceedings of the Lebedev Physical Institute, Russian Academy of Sciences, Moscow), Vol. 196, pp. 143–167, 1989.     

Study of optical properties and molecular structure of plasma polymerized diethylene glycol dimethyl ether

This paper deals with plasma polymerization processes of diethylene glycol dimethyl ether. Plasmas were produced at 150 mtorr in the range of 10 W to 40 W of RF power. Films were grown on silicon and quartz substrates. Molecular structure of plasma polymerized films and their optical properties were analyzed by Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy. The IR spectra show C–H stretching at 3000–2900 cm^-1, C=O stretching at 1730–1650 cm^-1, C–H bending at 1440–1380 cm^-1, C–O and C–O–C stretching at 1200–1000 cm^-1. The concentrations of C–H, C–O and C–O–C were investigated for different values of RF power. It can be seen that the C–H concentration increases from 0.55 to 1.0 au (arbitrary unit) with the increase of RF power from 10 to 40 W. The concentration of C–O and C–O–C decreases from 1.0 to 0.5 au in the same range of RF power. The refraction index increased from 1.47 to 1.61 with the increase of RF power. The optical gap calculated from absorption coefficient decreased from 5.15 to 3.35 eV with the increase of power. Due to its optical and hydrophilic characteristics these films can be applied, for instance, as glass lens coatings for ophthalmic applications.     

A method for determining optical constants, dimensions, and concentrations of “soft” absorbing particles in the brightening band region

We investigate the possibilities of creating a method for estimating the optical constants, dimensions, and concentrations of “soft” absorbing particles by applying a theoretical analysis of the angular dependence of the intergrated indicatrix, overall characteristics of light scattering, and absorption on the phase shift and diffraction parameter of particles in the brightening band region. We show that using the investigated optical characteristics, it is possible to determine the unknown parameters of a suspension from experimental data. Institute of Biophysics, Siberian Branch of the Russian Academy of Sciences, Akademgorodok, Krasnoyarsk, 660036, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 807–812, November–December, 1997.     

Stability conditions of a laser cavity with gaussian diaphragms

Laser cavities with spherical mirrors and Gaussian diaphragms have been investigated. The influence of the parameters of mirrors and Gaussian diaphragms on the stability conditions of such cavities is shown. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 465–468, July–August, 2000.     

Planetary Fourier spectrometer: An interferometer for atmospheric studies on board Mars 94 mission

Summary PFS is a two-channel Fourier spectrometer operating in the infra-red wavelengths between 1.25 and 45 μm. The instrument will be used mainly in the study of the Martian atmosphere. The principal goals are the measurements of the atmospheric temperature and pressure, atmospheric constituents, aerosol and clouds, ground pressure for surface topography, optical and thermophysics properties of the Martian soil. PFS will fly on the Mars 94 spacecraft which should be launched in 1994 and reach the planet in 1995. It is essentially constituted by two different interferometers located in the same box which is divided into two parts. A dichroic placed on the PFS entrance is used to separate the spectral range into two parts, a division needed by the different optical materials which have to be used in each spectral range. The optical layout of the experiment is very compact. Each channel uses two cubic mirrors mounted on an L-structure pivoted on a motor. The motor moves the mechanics and permits the optical-path difference between the arms to be varied. Each interformeter operates in a different spectral range, respectively, between (1.25÷4.8) μm (8000÷2083cm⁻¹) and (6÷45)μm (1666÷220)cm⁻¹). The spectral resolution is 2 cm⁻¹. The entrance aperture area is 30 cm² per channel and the field of view is 2 and 4 degrees. Every measurement lasts about 4 s. The time and, therefore, the relative optical-path difference for the measurement of every point of the interferogram is given by the zero crossings of the interferogram of a reference monochromatic channel at 1.2 μm which uses a laser diode as source. The two interferograms are double-sided and will have 16384 and 4096 points, respectively, corresponding to spectra of 6250 and 1823 useful points. Paper presented at the 6th Cosmic Physics National Conference, Palermo, 3–7 November 1992.     

Optical properties of multilayer materials based on silicon and nanosized magnesium silicide crystallites

We have studied the optical properties of silicon with incorporated nanocrystallites of semiconducting magnesium silicide by optical spectroscopy and Raman spectroscopy. We have calculated the optical functions of samples grown with different numbers of layers of incorporated magnesium silicide nanocrystallites. We have determined the contribution of magnesium silicide to the electronic structure of multilayer samples in the photon energy range 1.5–3.0 eV. We have studied the phonon structure of the grown multilayer samples, based on analysis of two-phonon and three-phonon resonances in silicon and Mg₂Si. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 204–209, March–April, 2006.     

大口径光学元件薄膜厚度均匀性修正

 研究了2.2 m高真空箱式镀膜机镀膜时的实际膜厚分布情况。对非球面和平面光学元件，分别采用行星夹具和平面公转夹具并利用修正板调节膜厚均匀性。从实验上实现了大口径薄膜均匀性的调节，并获得较为理想的结果。口径在700 mm范围内，对于凹面均匀性可以控制在0.7%以内，平面均匀性在1%以内；口径在1 200 mm范围内凹面元件均匀性可控制在1%以内，平面1 300 mm口径以内窗口均匀性可控制在1%以内。镀制了口径在400~1 300 mm的多种天文观测上使用的反射镜、增透膜等，获得了理想的光谱曲线与较好的使用效果。     

Ray tracing studies of a complete plane grating monochromator beam line

Optical design of a plane grating monochromator beam line for X-ray spectroscopic studies to be installed on INDUS-1 is studied using ray tracing technique. The main components of the beam line are pre- and post-elliptical mirrors and the plane mirror-grating dispersing system. The ideal positions of the optical components are decided by using our analytical formulation of the Riemer’s kinetic principle for reflecting synchrotron radiation onto the same spot of the dispersing grating. The program is developed indigenously and can be used on a PC. The tangent error and microroughness of the mirrors is explicitly accounted for in the program. The wavelength dependent absorption of radiation at the different reflecting surfaces is also included for calculations of the optical throughput. The dependence of the final image line shape and resolution on various beam line parameters is calculated. The results are useful in deciding the tolerances of the various beam line components and their positions.     

Directionality and mode structure of radiation of semiconductor lasers with electron-beam pumping

We present results of investigations of the directionality diagram and mode structure of radiation of semiconductor lasers with electron pumping that have microrelief reflectors instead of a blind mirror and output mirrors, whose coefficient of reflection depends on the wavelength and the angle of light propagation. Application of such mirrors allows one to narrow the spectrum of output radiation of the lasers, simultaneously reducing the threshold and increasing the output power. The discovered multilobe structure of the directionality diagrams is explained on the basis of geometrical optics. The possibility of controlling the directionality of radiation depending on the spectral and angular characteristics of the output mirror is shown. Reported at the Second International Scientific and Technical Conference on Quantum Electronics, Minsk, November 23–25, 1998. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 092–697, Septemter–October, 1999.     

Design and performance of two-channel EUV multilayer mirrors with enhanced spectral selectivity

In this paper, we present a study on two-channel multilayer mirrors which can operate at two wavelengths in Extreme Ultraviolet (EUV) spectral range. We propose a new method to design two-channel EUV multilayer mirrors with enhanced spectral selectivity. The mirror structure is a stack of two periodic multilayers separated by a buffer layer. We have defined the main parameters which allow adjustment of the distance between different order Bragg’s peak and of wavelength positions of reflectivity minima. Two mirrors have been designed and deposited for solar EUV telescope applications by using this method. The first mirror reflects Fe IX–X line (17.1 nm) and Fe XVI (33.5 nm) lines with attenuation of the He II line (30.4 nm). The second mirror reflects Fe IX–X and He II lines with attenuation of Fe XV (28.4 nm) and Fe XVI lines. Measurements with synchrotron radiation source confirm that, in both cases, for these mirrors, we are able to adjust reflectivity maxima (Bragg peak position) and minima. Such multilayers offer new possibilities for compact design of multi-wavelength EUV telescopes and/or for high spectral selectivity.     

Applicability of approximate methods of calculation of the frequency-contrast characteristics of aerosol layers within the wavelength range of 0.4–14 μm

The spectral dependences of the optical characteristics governing radiation transfer in scattering media are analyzed within the wavelength range of 0.4–14 μm for three types of aerosols. The wavelength ranges where approximate methods of calculation of frequency-contrast characteristics are applicable are established; the corresponding limitting masses of aerosol particles in a layer per unit of surface area are determined for which approximate methods provide acceptable accuracy. B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 70 F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 419–425 May–June, 1998.     

Multilayer x-ray mirrors

The angular, dispersive, polarization and energy features of multilayer x-ray optics are considered within the framework of unified theoretical approach. The ultimate optical parameters of multilayer structures are investigated, and the possibilities of their application to certain physical problems are discussed. Practical recommendations and techniques for fabrication of x-ray interference mirrors are considered. Translated from Trudy Fizicheskogo Instituta im. P. N. Lebedeva (Proceedings of the Lebedev Physical Institute, Russian Academy of Sciences, Moscow), Vol. 196, pp. 68–102, 1989.     

大型光学镜面的多点支撑方案分析

在大型光学系统中使用薄型镜面以减轻大口径光学镜面的重量，但由于薄镜面在重力作用下形变严重，需要选择适当的支撑方式来维持光学镜面的面形。通过对支撑方式的分析，采用有限元仿真，讨论了支撑点分布方式、支撑分布位置和支撑点数三方面对镜面形变的影响，从而得出支撑点均匀分布优于非均匀分布；支撑点数一定时，镜面形变主要由支撑点位置决定；10个支撑点以上镜面形变相对较小，继续增加支撑点并不能使镜面最大形变得到显著改善同时会引起镜面波纹起伏增加。     

Physical Analysis of a Possibility to Reach the 1.30-μm Emission from the GaAs-Based VCSELs with the InGaAs/GaAs Quantum-Well Active Regions and the Intentionally Detuned Optical Cavities

Physical aspects of an operation of the GaAs-based InGaAs/GaAs quantum-well (QW) VCSELs with the intentionally detuned optical cavities have been considered in the present paper using the comprehensive three-dimensional self-consistent optical–electrical–thermal-gain simulation. In GaAs-based structures, very good DBR resonator mirrors and a very efficient methods to confine radially both the current spreading and the electromagnetic field with the aid of oxide apertures may be applied. It has been found using the above simulation that even currently available immature technology enables manufacturing the above devices emitting radiation of wavelengths over 1.20 μm. In particular, while the room-temperature 1.30-μm lasing emission is still beyond possibilities of the InGaAs/GaAs QW VCSELs, these structures may offer analogous 1.25-μm emission, especially for the high-power and/or high-temperature operation.     

Generation of multi-axis Laguerre–Gaussian beams from?geometric modes of a hemiconfocal cavity

We study the transformation of multi-axis Laguerre–Gaussian beams from optical beams comprising Hermite–Gaussian modes with ray–wave duality. By use of cylindrical lenses, Hermite–Gaussian modes can be transformed into Laguerre–Gaussian modes possessing optical orbital angular momentum. The superposed Hermite–Gaussian modes localized on geometric trajectories are generated from a degenerate hemiconfocal cavity and transformed into multi-axis Laguerre–Gaussian beams. Experimental results of the structured beams are systematically manipulated and in good agreement with theoretical analyses.