摘要:

An astronomical camera is described which consists of a scanning Fabry–Pe´rot Interferometric (FPI) system coupled to a charge coupled detector (CCD) imaging system. The Fabry–Pe´rot etalon equipment consists of a commercially available Queensgate system. The CCD equipment is a commercially available Photometrics system employing one of the early developmental CCD chips of the Space Telescope Imaging Spectrograph (STIS) project. The camera is controlled by a Digital Equipment Corporation Microvax II computer. Control of a filter wheel system and other housekeeping duties are done through a Kinetic Systems Camac controller commanded by the computer.

ISSN:0034-6748    

DOI:10.1063/1.1145216

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A diagnostic method for high power CO2laser beams is presented. The technique features imaging of high intensity infrared radiation via the thermally induced luminosity of high velocity charcoal particles contained within an air stream. The method is particularly convenient for determination of focal position, depth of field, beam diameter, and spot size. Variations of these parameters with power level are easily observed utilizing this charcoal powder imaging method. Using this ‘‘real‐time’’ technique, focal spot size and location accuracy are ±0.1 and ±1 mm, respectively. Results are shown to be independent of micro‐particle size within specified limits. As a result, periodic, fine laser‐workpiece adjustment is now cost effective when working with high power lasers. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144481

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A novel preionization technique which uses a surface corona discharge to produce preionization electrons for the controlled low jitter breakdown of a main corona‐gap preionizer is described. The pre‐preionization scheme has been used to reliably preionize a long optical pulse (450 ns full width at half‐maximum) XeCl laser. The laser excitation circuit is a new version of the overshoot mode of magnetic‐spiker sustainer excitation specifically designed to be simple, reliable, and capable of high repetition rate operation. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144482

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

We present a narrow‐band and low‐intensity noise laser oscillator around 780 nm built from a commercially available laser diode. We have stabilized the frequency of two extended cavity diode lasers on the same high finesse Fabry–Pe´rot cavity using a wide‐band electronic feedback loop. We have reduced the relative linewidth of the two lasers down to 570 Hz and strongly concentrated their energy: 95% in a relative bandwidth smaller than 10 kHz. The intensity noise of this device corresponds to the shot noise for Fourier frequencies larger than a few megaHertz. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144483

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

Long optical pulses have been generated in a XeCl excimer laser by using a simple capacitor‐transfer discharge circuit consisting of storage capacitors charged at 26 kV and discharged through the electrodes, tightly coupled to the variable small peaking capacitors. By adjusting the [HCl] concentration and capacitance ratios, the typical pulse duration (20 ns) is stretched up to 150 ns (full width at half‐maximum). The transfer behaviors of the pulse duration from short pulse to long pulse are presented and analyzed extensively by measuring the discharge voltage profile, output energy, overall efficiency, optical waveform, and pulse duration, as functions of [HCl] concentration and capacitance ratios. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144484

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

An analytical technique, based on a generalization of the Stappaerts method which takes into account asymmetry elements, is proposed for discharge electrodes designing. In particular, compact electrode profiles are proposed for laser cells with current return bars and for double‐head lasers. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144485

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A computer controlled apparatus for laser flash spectroscopy has been constructed. Nitrogen laser (energy 1 mJ, pulse width 1 ns) is used both for excitation of the sample and for pumping a tunable dye laser which serves as a source of monitoring light. Two different scan modes are possible: (i) a scan with a fixed wavelength of the monitoring light: the temporal evolution of the transient absorption in the range from −2 up to 100 ns can be observed by changing the length of the variable self‐compensating optical delay line, or (ii) a scan with a fixed time delay: the corresponding transient absorption in the range 380–800 nm can be measured. For illustration, the transient absorption spectrum of benzophenone in methylcyclohexane, decay curves of the singlet state of benzanthracene in ethanol in the presence of a quencher, and a ‘‘negative absorption’’ of rhodamine B in nitriles are reported. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144486

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

In this paper, a novel miniature spectrometer is described which employs an integrated‐optic acousto‐optic tunable filter (IAOTF) as the monochromatic wavelength selective element. The performance of the system is highlighted by measuring the absorption spectra of two samples in the region of 1400 to 1600 nm. In the experiment, a light emitting diode (LED) centered at a wavelength of 1530 nm, is used as the light source and spectral filtering is achieved using an IAOTF that is tunable over more than 260 nm. The device exhibits a FWHM resolution of 1.2 nm, measures 25×3×1 mm3, weighs under 1 g and requires less than 70 mW of rf drive power. This miniature spectrometer offers several attractive design features that have utilities in a variety of applications, particularly for portable analysis and operation in harsh environments. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1145201

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

An automated version of a spectroscopic ac null ellipsometer is described. By simultaneous variation of the angle of incidence and the polarizer azimuth, circular polarization of the reflected radiation can be obtained for any sample configuration. This state of polarization is checked by a rotating analyzer detector system with lock‐in technique, thus achieving the highest precision that is theoretically possible. The experimental details including the minimization routine (simplex method) are presented. First experiences gained with dielectric function spectra of InP show the high reproducibility and accuracy of the arrangement. From numerically calculated second derivatives the energy and type of critical interband points are determined. ©1994 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1144487

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

A raytracing facility for evaluating soft x‐ray and vacuum ultraviolet optics, especially synchrotron radiation monochromators and beamlines, has been reported. Such kinds of optics consist of any number of reflecting mirrors, gratings, and, if needed, stop apertures: in coplanar or orthogonal configuration; conventional, holographic, and varied line‐space gratings are available dispersing elements in design of a monochromator. Both normal and grazing incidence optics can be handled well. Point or finite sources, necessary to be setup in the raytracing process, may be used of isotropic or of Gaussian distribution. The spot diagram or grey level image simulation will be produced. Finally, an example of its applications, raytracing of a Seya–Namioka monochromator beamline at NSRL, will be presented. ©1994 American Institute of Physics.  

ISSN:0034-6748    

DOI:10.1063/1.1144488

出版商:AIP    

年代:1994

数据来源: AIP