摘要:

Two laminar amplitude multilayer gratings with 250‐nm pitch were produced using UV holography and reactive ion etching. The diffraction properties of these structures were measured at 150 eV using synchrotron radiation. The experimental results, giving the position and absolute reflectivity of the various orders, are discussed within a kinematical model.

ISSN:0034-6748    

DOI:10.1063/1.1143835

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We present a measurement scheme which, if applied with a commercial spectroscopic ellipsometer, allows us to collect reliable data when the parameter tan  &psgr; is as small as 2×10−3. By using it we could determine the average amplitude of thermally excited capillary waves at the free surface of toluene.

ISSN:0034-6748    

DOI:10.1063/1.1143178

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A single mode GaAlAs semiconductor laser operating at around 830 nm has been locked in frequency to the center of an absorption line of molecular iodine vapor. A relative frequency stability of better than 10−9was obtained for time periods longer than 1 s. This stabilization scheme increases the flexibility of wavelength selection. A method has been developed to estimate the stability when only one stabilized system is available.

ISSN:0034-6748    

DOI:10.1063/1.1143179

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

To reduce the load on switching elements in the excitation circuit of excimer lasers, a new circuit has been developed to study the basic characteristics, where a saturable transformer is utilized in the magnetic pulse compressor. We have used a saturable transformer with a winding ratio of 1:4. The initial pulse of 8.5 kV, 2.0 kA, 3 &mgr;s was transferred to the output pulse of 34 kV, 8 kA, 109 ns, with an energy‐transfer efficiency of 58%. Using a saturable inductor as a charging inductor, furthermore, we have succeeded in reduction of the prepulse of the output voltage and enhancement of the energy‐transfer efficiency.

ISSN:0034-6748    

DOI:10.1063/1.1143180

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A driver for the stable‐frequency operation of an AlGaAs laser diode is described. This consists of a constant current source with short‐term fluctuations of ±8 &mgr;A and a drift of less than 2 &mgr;A in 10 h, in conjunction with a ±1 mdeg temperature controller. The current can be set to values up to 100 mA and a ramp current up to 20 mA can be added to this to allow frequency scanning of the laser. The laser linewidth is measured by heterodyning two such stabilized lasers and recording the beat note. This has a width of 27±7 MHz. The frequency drift is monitored by exciting theD2transition of cesium and recording the change in absorbed power when a laser is tuned to the side of an absorption peak. The drift is measured to be 10 kHz/s over 5 h, and is attributed largely to temperature drift. In addition, the current circuit can be readily interfaced to a microcomputer for automatic control of the laser current without sacrificing stability.

ISSN:0034-6748    

DOI:10.1063/1.1143181

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

This paper proposes and analyzes a technique that will allow the spatial coherence properties of short‐wavelength radiation sources to be measured. The technique is based on the analysis of the partially coherent diffraction patterns produced by a uniformly redundant array.

ISSN:0034-6748    

DOI:10.1063/1.1143130

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The intention of this paper is to describe the design of a 16‐bit correlation setup employing a personal computer (PC) used in intensity fluctuation spectroscopy. It is based on a hardware acquisition board which counts the photons detected in the selected sampling time. The calculation of the correlation coefficients is achieved with a PC by means of a suitable software program. This arrangement permits one to obtain various kinds of information from the recorded data, i.e., it is possible to evaluate other statistical estimators instead of the usual correlation function. Experimental tests of the apparatus have been obtained by measuring the light scattered by a liquid suspension of polystyrene latex spheres.

ISSN:0034-6748    

DOI:10.1063/1.1143131

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Simple modifications were made to a commercial microscope to enable injection of light from a diode laser, and demonstrate optical tweezers action. The basic properties of microscope optics are presented together with discussion of principles to be followed in arranging the external optics for achieving useful tweezers. Procedures using a single‐mode diode laser along with experimental results are presented in enough detail to permit readers to make their own system for trapping and manipulating single cells. It is surprisingly easy to demonstrate tweezers action once some basic concepts are understood.

ISSN:0034-6748    

DOI:10.1063/1.1143833

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Two configurations for a fiber‐optic torsional vibrometer are described, which can be classified as (i) differential and (ii) reference. Common features of both techniques are noncontact measurement, immunity to nontorsional vibration, large dynamic range coupled with passive, miniature, remote sensor heads. Measurements of rotation speed and torsional jitter were made with a total illuminating laser power of 130 &mgr;W (reference mode) and 1.5 mW (differential mode). Rotation speeds in the range of 270–19 000 RPM were measured.

ISSN:0034-6748    

DOI:10.1063/1.1143132

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A diode laser based system was developed to monitor the mean concentration of aerosol clouds formed by cylindrical liquid fuel‐air explosive (FAE) devices. Characteristics of the aerosol clouds are first described to provide an understanding of the nature of the flow which led to the engineering design of the system used. This paper then concentrates on the construction and testing of this optical system, which was designed to carry out four simultaneousinsitulight extinction measurements through FAE clouds. The results of a typical liquid fuel dispersion test are presented and discussed as an illustration of the characteristics of the optical system in this application.

ISSN:0034-6748    

DOI:10.1063/1.1143133

出版商:AIP    

年代:1992

数据来源: AIP