Total Reflection Mirrors Research Articles

Ultrasonic laser modulator

An ultrasonically modulated laser comprises a laser oscillation tube including opposing ends for generating a beam of planar polarized light having a plurality of wavelenghts; an output mirror at one end of the tube for reflecting the light beam; and a modulation device at the other end of the tube for simultaneously modulating a plurality of wavelengths of the light beams, including an acousto-optical prism having an incident surface for separating the beam into multiple wavelength components, a total reflection mirror for receiving and reflecting selected wavelength components impinging on the incident surface from the tube at a predetermined angle, and an ultrasonic transducer for generating standing means perpendicular to the selected wavelength components for modulating the reflected selected wavelength components.

Multilayer mirrors as power filters in insertion device beamlines

The power-filtering capabilities of multilayer bandpass x-ray mirrors relative to total reflection low-pass mirrors are presented. Results are based on calculations assuming proposed wiggler sources on the upcoming generation of low-energy (1.5 GeV) and high-energy (7.0 GeV) synchrotron radiation sources. Results show that multilayers outperform total reflection mirrors in terms of reduction in reflected power by roughly an order of magnitude, with relatively small increases in total absorbed power and power density over total reflection mirrors, and with comparable reflected flux values. Various aspects of this potential application of multilayer x-ray optics are discussed.

Optimized beamline design for macromolecular crystallography at the Cornell High Energy Synchrotron Source (CHESS) (abstract)

The A1 station on the CHESS wiggler beamline has been the workhorse for most macromolecular crystallographic experiments. This station is equipped with a fixed energy focusing germanium (111) monochromator and a focusing total reflection mirror. Our macromolecular crystallographers made full use of the high flux of more than 1012 photons/s/mm2 and the stable beam conditions, both in position and energy resolution. As a result, the A1 station was heavily oversubscribed. CHESS is presently expanding its capabilities and a new diffraction station for macromolecular crystallography is under construction. This beamline will be powered by a 24-pole hybrid permanent magnet wiggler with a critical energy of 25 keV. A focusing monochromator, which handles a specific heat load of 10 W/mm2, will have a range of tunability which covers all relevant absorption edges from 7 to 15 keV using a Ge(111) crystal. The energy resolution and the focusing properties remain constant within a factor of 2 over the entire tunability range. We expect a brilliance of about 1013 photons/s/mm2/mrad2/0.1% bandpass. The diffraction station will be equipped with an oscillation camera which can be used with x-ray film of 5×5 or 8×10 in. size or alternatively with Kodak storage phosphors. A wide variety of clamp-on accessories, like crystal coolers, fast shutters, helium pathways, polarimeter, etc. are available. The station will contain a beampipe system, which can also be used for small angle scattering experiments with sample-to-detector distances of up to 3000 mm. The entire diffraction station, its control area, a biological preparation area, and a darkroom are to be embedded in a biological safety containment of the level BL3. This will allow diffraction studies of virulent strains of viruses and other biohazards, which could not previously be studied at synchrotron radiation sources before without causing major disruption to the normal laboratory procedure.

Higher-harmonics suppressor for soft x rays

We have developed an apparatus for suppressing higher harmonics contained in the soft x-ray output beam of grazing-incidence grating monochromators. It consists of eight pairs of total-reflection mirrors. Each pair serves as a low-pass filter with the cutoff energy different from one another. The eight pairs are designed to cover an energy range of 80–1600 eV with an efficiency of harmonic suppression better than 97%, while transmitting more than 50% of the fundamental photons. We have tested its preliminary performance on the soft x-ray beamline BL-8A at the Photon Factory. We present the observed transmission efficiencies and the effects of the harmonic suppressor on measurements of reflectivity and fluorescence spectra.

Surface-emitting GaAs/AlGaAs lasers with dry-etched 45° total reflection mirrors

Surface-emitting GaAs/AlGaAs lasers with 45° total reflection mirrors have been successfully produced using a 45° tilted reactive ion beam etching technique. The ratio of surface-emitted light output power to edge-emitted light output power was obtained at values as high as 77%. The total reflection mirror was formed within 1° of the desired precise 45° angle. This type of surface-emitting laser is promising for optoelectronic integrated circuits because of the simplicity of its structure and fabrication.

Pulsed CO2 laser utilized ultrasonic vibrator.

Q-switched CO2 laser has been investigated, in which the total reflection mirror of the laser resonator was attached to the ultrasonic vibrator and was vibrated along the axis of the resonator. In this method, there is a problem that multiple pulses may occur in a period of vibration. It is possible to decrease the number of pulses in a period by reducing the displacement of the vibrating mirror. But in the vicinity of the resonant frequency of the ultrasonic vibrator (-17 kHz), with smaller displacement the peak pulse power decreases and its pulse width becomes wider. There exist higher frequency bands (40-80 kHz) in which weak vibration of the ultrasonic vibrator occurs. In these frequency bands, single pulse with higher peak power and narrower width compared with the pulse appeared in low frequency band was obtained.

The 6 m point-focusing small-angle X-ray scattering camera at the high-intensity X-ray laboratory of Kyoto University

A new multipurpose X-ray small-angle scattering camera system consisting of a rotating-anode X-ray generator, a double-focusing collimator and a two-dimensional position-sensitive detector has been developed at the High-Intensity X-ray Laboratory of Kyoto University. The overall camera length is 6 m, and the sample-to-detector distance can be varied in 0.5 m increments up to 3 m to cover scattering angles ranging from 0.001 to 0.18 rad. The collimator consists of a pair of crossed-plane total-reflection mirrors of 40 cm in length. The mirrors, which are mechanically bent to form cylindrical surfaces, provide point collimation free of collimation error. General-purpose sample holders equipped with a programmable temperature controller are provided for both transmission and scattering measurements; the temperature is maintained within ± 0.1 K in the range of 223–573 K. A cryostat for measurements down to 20 K, a dynamic sample deformation apparatus, and a temperature-jump equipment are also available. The multi-wire delay-line position-sensitive proportional counter has an active area of 128 × 128 mm with a spatial resolution of 0.5 × 1.0 mm. The data acquisition is controlled by a real-time front-end processor through a CAMAC interface. The data are recorded in a dual-port histogramming memory of 32 bit × 1 Mwords, which enables direct access to the data from the main computer for real-time monitoring and analysis. The performance of the camera is demonstrated with some selected examples: diffraction patterns from carp lateral line nerve myelin and chicken-tendon collagen fibrils, a Guinier plot of the scattering from polystyrene in dilute solution, and time-resolved measurements of polypropylene during the annealing process.

Multilayer-coated mirrors as power filters in synchrotron radiation beamlines

Multilayer-coated mirrors, rather than conventional total-reflection mirrors, have been proposed as a means to reduce power incident on the first optical element of high resolution monochromators. We have designed, fabricated, installed and characterized a multilayer premirror specifically for the 800–4000 eV range for the X-24A bending magnet beamline at the National Synchrotron Light Source. Various aspects of this application are discussed, including power and thermal considerations, beamline layout considerations and constraints, choice of multilayer materials and substrate, and techniques to ensure lateral uniformity of the multilayer. Results of a preliminary characterization of a mirror coated with a SiC/V multilayer and installed in the beamline are also discussed.

Measurements of Soft and Ultrasoft X-Rays with Total Reflection Monochromator

The development of X-ray spectrographic analysis of light elements, which are O, C and B, has bee n performed for many applications using an end-window type X-ray tube with Rh-target and thin Be-window, wavelength dispersing devices, which are synthetic multilayers or total reflection mirror (with a specific filter) and a gas flow proportional counter with a thin film window. In Fig. 1 factors related to the intensity measurements in X-ray fluorescence analysis are shown. The excitation efficiency in the soft and ultrasoft X-ray region is very low because of the lower intensity of primary X-rays and low fluorescence yield of light elements. Instead of the wavelength dispersive method of Bragg reflection, having high resolution and low reflectivity, monochromatization combining total reflection by a selected mirror and an appropriate filter offered an alternate approach in order to increase measured intensity with reasonable optical resolution. Synthetic multilayers which have higher resolution and lower intensity compared with the performance of the mirror method have become popular for the detection of soft and ultrasoft X-ray region.

A systematic method of estimating the performance of X-ray optical systems for synchrotron radiation. I. Description of various optical elements in position–angle space for ideally monochromatic X-rays

The performances of various optical elements are presented for ideally monochromatic X-rays in terms of position–angle space, which is used in the phase-space method. The optical elements discussed are a synchrotron radiation source, flat perfect crystals (reflection and transmission geometries), mosaic crystals, curved crystals of reflection (Johansson, Johann and logarithmic spiral types) and transmission geometries, and an elliptic total reflection mirror. The angular widths of acceptance and emergence for diffraction are properly taken into account in both the flat and curved crystals. It is shown that focusing optical elements such as a curved crystal and an elliptical mirror should not be treated simply as lenses.

X-Ray Diffraction Methods in Molecular Physiology

A survey is made for recent development in X-ray diffraction studies on the excitable tissues, with special emphasis upon biological and lipid membranes.The exposure or counting time needed to observe diffraction patterns from muscles and membranes has been very much shortened recently by the combined use of the total reflection mirror, the curved monochrometer and the position sensitive proportional counter.There are two approaches in determining ρ (z) of membranes from diffraction data, where z is the coordinate normal to the membrane and ρ (z) is the projection of the electron density distribution to the z axis. One of them is to use Bragg reflections from the lamellar phase of membrane-water system and the other is to use continuous diffraction patterns from membranes dispersed in water, where relative positions of membranes have no correlation. These two approaches are discussed referring to results on lecithin (dipalmitoyl phosphatidylcholine) membranes obtained recently by Y. Inoko and by T. Yamaguchi and K. Furuya. The former has investigated the lamellar phase of the lecithin-water system and the latter have obtained continuous diffraction patterns in good contrast from UO2++ -decorated lecithin double layers dispersed in water. Calculated ρ (z) in these two cases are presented.