Mirror Holder Research Articles

A total-reflection X-ray fluorescence spectrometer using a rotating anode

Abstract A total-reflection X-ray fluorescence (TXRF) spectrometer has been designed for an 18 kW rotating anode system. The spectrometer uses a multilayer mirror, which is especially advantageous in the analysis of biological samples, and a charge-coupled device (CCD), which is an aid in the alignment of the instrument. To ensure spectrometer stability, the collimator, multilayer mirror and sample holder are connected directly to the housing of the rotating anode while the detector rests on a separate support. With the CCD, the intensity distribution of the X-ray beam was measured; and the beam thickness at the sample position was calculated. A relative sensitivity calibration curve was established for the spectrometer and shown to agree well with a theoretical expression. The calibration was validated by measurements on a certified reference material of plankton. The measurements also provided information about the accuracy, precision and detection limits of the spectrometer for biological samples.

PLS bending magnet x-ray beamline 3C2

The design of the 3C2 beamline at the Pohang Light Source (PLS) is described. The beamline is designed for x-ray scattering studies with x-ray photons over an energy range of 4–12 keV. A cylindrical Pt-coated silicon mirror intercepts a photon beam up to 3 mrad at a distance of 16 m from a source point and focuses the beam sagittally at the sample position with a magnification of 1:1. For the vertical focusing it will be dynamically bent by the mirror holder. A double-crystal monochromator of two Si(111) crystals with a fixed-exit beam geometry provides monochromatic photons and is located in front of the experimental hutch to reduce the motion of the beam position. The hutch is equipped with a four-circle diffractometer and various photon detection electronics for x-ray scattering experiments.

A VUV beamline (ABL-3B) for real-time photoelectron spectroscopy at the NTT synchrotron radiation facility

A VUV beamline (ABL-3B) for real-time photoelectron spectroscopy has been developed at the normal-conducting accelerating ring (NAR) of the NTT synchrotron radiation facility. To accept the incident synchrotron radiation beam with the wide horizontal divergence angle of 20 mrad, a 1.38-m-long cylindrically bent front mirror was devised. This mirror was composed of four plane mirror blocks connected together and mounted on a steel holder beam having a C-shaped cross section. The mirror holder can be bent by a novel bending device with a momentum of 1388 kg cm to achieve the optimum radius of the curvature of 63.9 m. The focused spot of 3.5 mm (H)×1.8 mm (V) was preliminarily obtained on the sample position by bending the front mirror. When the stored electron beam current was 50 mA and the “grasshopper” monochromator was tuned at 130 eV, a photon flux of 1.5×10 10 photons/s was obtained with the energy resolution of 0.5 eV.

High-Speed Access Mechanism for 90 mm 1-Inch-High Optical Disk Drive

A 90 mm, 1-inch-high optical disk drive with a 17-mm-high mechanism and a 27 ms seek time was developed using a separated optical system with an improved galvanomirror. This optical layout reduced the weight of the movable optical part to 7 g. The maximum acceleration of 127 m/s2 was driven by 8 W. The major component parts of the galvanomirror, such as the mirror holder and base, were made of anisotropic liquid-crystalline polymer. The use of this material, which has high rigidity and low thermal expansion, resulted in optical spot drifting due to mirror rotation of less than 3 µm from room temperature to 65°C.

Fabry-Pérot resonators with oscillating mirrors.

In this paper we derive analytic expressions of the field on the mirror surfaces of a pendular and misaligned Fabry-P\'erot resonator by taking into account longitudinal and transverse optical modes. In particular, we obtain analytic expressions of the spectral components of the power reflected by these devices for oscillating mirrors and modulated laser beams. In addition, we discuss the equations of motion of the mirror holders and analyze the onset of instabilities induced by the radiation pressure, by accounting for transverse optical modes and torsional oscillations of the multiple pendula to which the mirrors are suspended.

Fully automated electrophoretic light-scattering device

A new electrophoretic light-scattering experimental device, fully automated, compact, and very easy to use, is described. It is completely driven by a microcomputer which controls the different experiment steps, performs the data acquisition in 128, 256, or 512 points, the fast Fourier transform analysis of the photocurrent for different frequency bandwidths, 10, 20, 50, 100, 200, 500 Hz, and performs all mathematical calculations needed before displaying the results. The optical setup is a heterodyne device, using two separate beams. A focusing lens (f=30 cm) and the chosen geometry allows one to improve the signal-to-noise ratio and to work with one coherence area. A special mirror holder permits one to select scattering angles from 1° to 50°. The chamber is thermostated. Its coating (in order to minimize electro-osmosis) has an average working lifetime of 8 h. The use of this experimental device for a colloid solution of 25 mg/ℓ of TiO2 (1 μm) in 100 mg/ℓ of KCl, and 10 mg/ℓ of Na4P2O7, pH=6.8, gave an electrophoretic mobility μ=(−3.27±0.17)10−8 m2s−1 V−1 at 20 °C in good agreement with results found in the literature.

FEL optics coating test device

A crucial issue concerning FEL is the resistance of the mirrors to high flux. In the example of the ACO storage ring, the high X-ray flux of spontaneous emission sets a limit to the shortest wavelength. A detailed analysis of the resistance of multilayer dielectric TiO 2 SiO 2 mirrors has been carried out. Several degradation processes have been identified occurring at different energies of incident photons leading to either surface or bulk absorption. This data was very important for the operation of the FEL at wavelengths above 460 nm. For shorter wavelengths almost nothing is known about the resistance of normal incidence multilayer mirror under X-ray exposure. At Orsay we are starting a program of work to test various mirrors under such conditions. A device has been built for this purpose, allowing consecutive irradiation of more than 12 mirrors without any ultrahigh vacuum break. Precision alignment screws are provided to align the mirrors with a reference mirror in order to continuously monitor the reflectivity during X-ray exposure. A thermocouple is located on the mirror holder. The device will be inserted on the ACO storage ring in the fall of 1986. The results of this program are essential for the future UV-VUV SUPER-ACO FEL and for any other storage ring FEL.

High-luminosity visible and near-IR Fourier-transform photoacoustic spectrometer

A visible and near-infrared (0.36-3-microm) Michelson interferometer has been built to perform Fourier transform photoacoustic spectroscopy. The scanning (step and integrate) and the internal modulation are obtained with only one active element: the moving mirror holder driven by a linear motor. The signal-to-improvement and the performance of the spectrometer are compared with other photoacoustic methods and illustrated by various spectra.

Standardization for serial intraoral photography

A recently developed system of mirror holders which makes the taking of standardized intraoral photographs less time consuming and more precise has been described. By fixing the relationship of the intraoral mirror to the camera, all that is necessary is to consistently orient the mirror to the teeth being photographed. Because the operator no longer has to position the mirror with one hand while holding the camera in the other hand, the whole operation of intraoral photography is greatly simplified. By producing serial slides of the progress of orthodontic treatment, a visual sequence of treatment can be prepared for viewing by patients, for educational purposes, and for showing at meetings and study clubs.

Device for reusing damaged laser mirrors

A simple mirror holder which permits the use of locally damaged laser morrors by allowing the undamaged areas of the reflector to be aligned along the laser optic axis is described. The mirror holder has an eccentric step for housing the mirror and a concentric aperture through which the undamaged surface of the reflector is utilised. By varying the eccentricity and by rotating the mirror inside the step the entire surface area of the reflector can be used successively.

Extension of the theory of the oscillating-disk viscometer for large boundary-layer thicknesses encountered at low pressures

After summarizing the exact solutions for the oscillating viscometer, the paper extends the theory of the instrument to include the case of larger boundary-layer thicknesses encountered at very low pressures. A correction factor has been included to allow for the edge effects, the effects from secondary flow and the effects produced by the chuck and the mirror holder attached to the oscillating body. The working equation has been presented.

Effect of laser radiation on the properties of dielectric multi-layer laser mirrors

Effects of laser radiation on the properties of dielectric multi-layer mirrors in the discharge tube of a HeNe laser have been studied. Mirrors consisting of 21 layers of ZnS and cryolite have been used. The complex effect of laser radiation has been investigated, particularly the effect of the laser beam and the effects of glow discharge products in a HeNe mixture which is in contact with the mirrors. The geometrical distribution of radiation damage has been found, and the degree of relative radiation damage has been considered in dependence on the exposure of mirrors to radiation. It has been found that the maximum decrease of the reflection coefficient is caused by the sputtering of the material of the mirror holder.

Integrating and other galvanometers

The theory, design, and construction of an integrating galvanometer is discussed. It has a free period of 80 sec and the damping/control ratio is sufficiently large to measure the change in flux produced in an exploring coil of considerable resistance connected in series with it, even though the flux change lasts over a period of several minutes. The small control is achieved by attaching a magnetized needle to the upper end of a glass tube fixed to the moving coil system. The needle swings in an auxiliary field whose polarity is reversed with respect to that of the needle. To avoid thermoelectric drifts the electrical circuit is made entirely of copper. To avoid zero drifts in the nature of magnetic hysteresis, the moving coil and its clips, the mirror holder and ligament holder are constructed from non-magnetic copper. Zero drifts due to mechanical hysteresis are eliminated by using very fine copper ligaments to lead the current in and out of the moving coil. Great care is needed in constructing, attaching, and ageing these ligaments. Some degree of seasoning of the suspension strip proves beneficial also. It has been experimentally established that whilst the greatest care is required in winding and preparing coils for sensitive galvanometers in order to avoid magnetic contamination, the main, if not the entire, source of magnetic impurity is invariably embedded in the wire. The device of using a magnetized needle, but not in an opposing field, is well adapted to design of standard galvanometers having various free periods and used in underdamped, critical, or overdamped conditions. Stable instruments having relatively short free periods have been designed and constructed for specific purposes. The effect of shunting the integrating galvanometer is theoretically examined, and the result obtained has been confirmed experimentally.