摘要:

We have developed a computer‐controlled double‐grating spectrometer system designed for spectral analysis of low level light sources, in particular Raman scattering spectroscopy. This system incorporates a 16‐bit minicomputer, a double‐grating spectrometer, and various output devices. We have used this system for Raman spectroscopy of light scattering from opaque surfaces and found it valuable in the numerical analysis of weak spectra.

ISSN:0034-6748    

DOI:10.1063/1.1686666

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A thermistor type adiabatic calorimeter has been designed with the capability of measuring the heat of wetting of high surface area solids in organic liquids. Since the primary source of error in this type of experiment is trace water in the organic liquid, a method has been devised for introducing freshly distilled liquids directly into the calorimeter vessel and for maintaining dry conditions while introducing additional sample bulbs for measurements. The main feature in the design of the calorimeter vessel is the arrangement for removing the sample and readmitting a new sample under a positive pressure of dry nitrogen. This design allows this single‐bulb calorimeter to achieve the advantages of a multibulb calorimeter for detecting the presence and effects of trace water in the organic wetting liquid. The sensitivity of the calorimeter, which contains a volume of 50–100 ml, was found to have an experimental uncertainty of ±0.03 cal. A series of heat of immersion experiments of NiO in organic liquids, where consecutive immersions were determined in the same liquid, yielded reproducibility results which were within experimental error and indicated that water was not present in measurable amounts in the wetting liquid.

ISSN:0034-6748    

DOI:10.1063/1.1686667

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A device for determining velocity pin spacings in a gas gun to within 0.002 mm is described, yielding projectile velocities to within 0.1%.

ISSN:0034-6748    

DOI:10.1063/1.1686668

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A time‐of‐flight detection system and apparatus have been developed to obtain photoelectron spectra for electron energies between 0 and 1 eV. This method has the advantage of collecting and analyzing photoelectrons of all energies simultaneously and therefore compensating for low signal levels due to low light intensities or small ionization cross sections. The collection efficiency and energy resolution are highest for electrons with near zero kinetic energy (≤100 meV). This technique has made it possible to obtain photoelectron spectra with a continuum light source dispersed by a monochromator. It is thus particularly useful for the study of autoionization events. Also presented are calculated potentials in 3‐dimensional rectangular acceleration regions and the effect of initial kinetic energy on space focusing in nonconstant electric fields.

ISSN:0034-6748    

DOI:10.1063/1.1686669

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

It is suggested that position‐sensitive detectors may be used to observe the time history of sample motion, such as that which takes place when impulse is imparted to a material sample during blowoff. In this application a laser beam is reflected from the rear surface of the sample or from a mirror attached to the sample, and the detector reproduces the time history of the position of the reflection. In this work the response of this type of detector to a rapidly moving laser beam has been studied. It has been found that detectors selected from those presently available can reliably locate the centroid of a laser beam that moves at least as fast as 0.19 cm/&mgr;sec. It is suggested that a reasonable criterion for determining the maximum velocity with which a detector may be used is &ngr;≤&Dgr;X/0.5RdC, where &Dgr;Xis the desired position resolution andRdandCare the distributed resistance and capacitance of the detector, respectively.

ISSN:0034-6748    

DOI:10.1063/1.1686670

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An electromechanical scanner‐display system is described that as a scanner measures optical density in transparencies and as display device reconstructs the scanned image from digitally recorded optical density data. The instrument can accommodate image sizes up to 20×25 cm with maximum spatial resolution of 20 line pairs/mm. The optical density data are digitized into eight bits (256 levels) covering a range of 0–2.2 OD at a speed of 28 000 samples/sec. The display part of the system receives data digitized into 256 levels; out of these 95–105 can be distinguished at at output with statistical significance.

ISSN:0034-6748    

DOI:10.1063/1.1686671

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Utilizing a light‐reflective transducer as sensor and an integrated circuit phase comparator for error detection, the rotation rate of an ordinary permanent‐magnet dc motor can be controlled throughout wide ranges of both speed and load with the same precision as can the frequency of an oscillator. Both motor adaptations and circuitry are simple and relatively inexpensive.

ISSN:0034-6748    

DOI:10.1063/1.1686672

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A scatter‐hole x‐ray camera has been designed and flown in a rocket to measure solar x radiation. Its distinguishing feature is that many single pin‐hole images are allowed to overlap—a multiplexing approach that saves space, gives practical signal‐to‐fog ratio, and requires special object reconstruction techniques. It was possible to reconstruct the appearance of the dominant source of solar emission on the day of rocket flight with better than one arc minute resolution. The coronal x‐ray region had the same general shape and intensity distribution as the associated calcium K‐line region

ISSN:0034-6748    

DOI:10.1063/1.1686673

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

This paper presents an improved version of the low temperature direct current comparator described originally by Harvey. The comparator described herein exhibits a resolution of 1.5 nA ·turn and provides ratios which have uncertainties of less than 4 parts in 1010. An alternate approach to the shielding of the windings is discussed and a preliminary comparator based on this concept is shown to have equally good performance. The latter comparator is probably better suited to the attainment of large current ratios.

ISSN:0034-6748    

DOI:10.1063/1.1686674

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An electro‐optic phase modulator has been constructed for use in time‐resolved laser interferometry. A set of lithium niobate crystals in tandem, driven by a fast sawtooth generator, provides a reference phase modulation of up to four fringes per microsecond at 3.39 &mgr; wavelength.

ISSN:0034-6748    

DOI:10.1063/1.1686675

出版商:AIP    

年代:1974

数据来源: AIP