Standard Light Source Research Articles

Age and the Perception of a Modulating Traffic Signal Light in a Field Location

Young, middle, and older drivers were motored towards a traffic signal face and were required to report whether the illuminated signal lens was modulating. No significant differences were found among the three age groups in the distance at which modulation was first reported nor in the change of the modulation pattern as they approached the signal face. The modulating of the illuminated green lens was perceived significantly further away than was the red lens. These distances increased during trials associated with inclement weather. Seventy-four percent of the observers indicated that the modulation attracted their attention. Of these, 64% reported a preference for the use of the modulating light in the traffic signals as compared with the standard light source. Implications for improving safety at intersections for the older driver are discussed.

Absolute standardless calibration of photodetectors based on quantum two-photon fields

A new method of absolute calibration of photodetectors based on a nonclassical effect in nonlinear optics is discussed. The combined influence of a monochromatic flux of pump photons and quantum vacuum noise on a nonlinear crystal with no center of symmetry results in the appearance of rigorously correlated pairs of photons with continuous spectral distribution in the spontaneous parametric scattering of light (spontaneous parametric downconversion) process. The presence of an optical field in a broad spectral range created by the two-photon states (biphotons) makes it possible to develop a new method of measuring the spectral distribution of the absolute value of the quantum efficiency of photodetectors, both in photon counting and in analog regimes, that does not use any calibrated standard light sources (étalons). The feasibility of the method is demonstrated on different types of photomultiplier tube.

Crosslinking proteins to nucleic acids by ultraviolet laser irradiation

Ultraviolet (UV) irradiation can initiate complex formation between proteins and DNA or RNA and so can be used to study such interactions. However, crosslink formation by standard UV light sources can take up to several hours. More recently, a beam of monochromatic UV light from a laser has been used to initiate crosslinking in nano- and picosecond time intervals. As noted in an earlier TIBS article ‘the advantages of short pulse times and high-energy fluxes should make this a valuable technique in the future’ 1. In this review we characterize laser-induced crosslinking and explore the applications of the method.

Photographic Colour Temperature for Standard and Non-Standard Light Sources

AbstractThe effects of differing spectral power distributions of both Planckian and non- Planckian radiators are examined in terms of their photographic colour reproduction. It has been shown that with knowledge of the emission spectrum, E(X), of any light source, and the blue, green, and red relative spectral sensitivities of a colour film, SfA), the primary colour photographic effectiveness, (e), of the light source on each layer can be determined and hence, filtration calculated in order to achieve a suitable neutral balance in the reproduction. A simple, novel, systematic photographic method for the determination of correct filtration for optimization of colour reproduction without a priori knowledge is described following this principle.

Color changes of composites on exposure to various energy sources

The color stability of composites, on exposure to irradiation (1) by a 150 klux xenon lamp, (2) a standard RS light source and (3) at elevated temperature at 60°C, in air or water and under different experimental conditions was determined for various times. Composites studied included chemically and light cured hybrid and microfilled resins and a material copolymerized by light and chemical aftercure. Color changes of composites intensified on increasing the irradiation time. Exposure to the 2 light sources under similar conditions gave comparable results. Visible light cured materials studied were more color stable than 2 common chemically cured composites. Light shades yielded more visible color changes than dark shades of the same brand. There was a significantly more severe discoloration of composites kept in water at 60°C than for those stored in air. Comparison with results in 2 clinical studies of color changes, using 2 of the chemically cured composites investigated here, indicates that these 2 restoratives, which pass the ANSI/ADA or ISO specification tests, discolor in clinical use after 2–3 years.

Absolute Intensity of Soft X-Rays of Synchrotron Radiation from the ETL-Storage Ring

The absolute intensity of X-rays in synchrotron radiation from the ETL-storage ring was measured using a proportional counter with a mylar (45 Å region), aluminum (8.3 Å region) or titanium window (2.7 Å region). The measured intensities were compared with those by calculation based on Schwinger's formula. The several parameters necessary for the calculation were obtained using the measured values and data from the literature. A comparison showed that the synchrotron radiation from the ring is suitable as a standard light source in these soft X-ray regions, and it was found that absolute intensity measurements in soft X-ray regions serve as accurate diagnostics for this storage ring.

加重平均法によるキセノンランプの分光分布修正

加重平均法によるキセノンランプの分光分布修正

Four-Dimensional Holograms from Time-Lapse Cinematography

Abstract New techniques in holography allow standard motion picture film to be converted to holograms that are visible with standard light sources. Time-lapse photographs of clouds have been converted to two types of holograms. One hologram was made from film taken by a camera at the ground. and shows, in a wall-mounted unit, cloud growth and movement. The other was made from film taken by an aircraft side camera during a cloud circumnavigation, and displays the four-dimensional structure of a cumulonimbus in circular hologram. The potential is described for similar products to be derived from other data sources relevant to meteorology.

歯冠色に関する研究 心理メトリック量を応用した歯冠色カラーチャートおよびシェードガイドの色彩域について

On studying the color of the natural tooth, as a means to record the tooth crown color objectively, color chart must be necessarily made so as to define the color range and plot it.This time, concerning the color distribution of tooth crown color, in addition to the relations with Munsell color system taken up ever widely in the color study, color chart is made by using psychometric quantity highly relative to the psychophysical quantity based on psychoperceptive quantity presented by HUNT. R. W. G.Color chart made and shade guides (VITA: Lumin Vacuum, DENTSPLY: Trubyte Bioform, SHOFU: Real crown, GC: Plastic Teeth) are spectro-measured JIS Z 8722 by using spectrophotometer, type M 307 of HITACHI. There expressed CIE L* a* b* uniform color system, it becomes indisputable that with respect to the color-rending property of the color chart made at standard light source C with vision field two degree, the way of valuation for the vision varies at standard light source D65and A in case of changing of the light source from one to the other.

加重平均によるキセノンランプの分光分布修正

加重平均によるキセノンランプの分光分布修正

Comparison between measured and calculated absolute intensities of ultra-soft X-rays of synchrotron radiation

Absolute intensity has been measured using a proportional counter with a mylar window for quasi-monochromatic ultra-soft X-rays from the ETL-storage ring. The measured photon numbers were compared with those calculated from Schwinger's formula and experimental parameters. The result suggests that the ring is qualified as a standard light source facility. It was found that absolute intensity measurements at a few tenths of the critical wavelength are capable of making accurate storage ring diagnostics.

Kinelaryngoscopy for documentation of laryngeal pathophysiology.

Viewing the larynx has been revolutionized by the advent of the flexible fiberoptic nasopharyngolaryngoscope. For the first time a subject may inspire, expire, cough, swallow, phonate sounds, words, sentences, passages, and sing in full voice as examination and photodocumentation procede. Combining the flexible fiberoptic nasopharyngolaryngoscope with a home video camera, a standard fiberoptic light source, a standard videotape recorder, and a standard color TV set, the author details a method for the production of color and sound videotapes of the larynx in action. The video images are of excellent quality, and may be made in straightforward and economical manner. In fact, the entire array of instrumentation, including the flexible fiberoptic nasopharyngolaryngoscope, light source, video camera, lens, adapter, camera mount, videotape recorder, and TV set may be purchased for significantly less than the cost of the camera that most physicians use for endoscopic photography. The concept of flexible fiberoptic examination of the larynx and videophotodocumentation of the larynx in respiratory, sphincteric, and phonatory action shall be referred to as "kinelaryngoscopy."

An Alternate Approach to Background Correction in Atomic Absorption Spectrometry

An alternate approach to implementing the background correction method originally proposed by Smith and Hieftje has been developed. Its novel feature is that only a single, short duration, high current hollow cathode lamp power pulse is used per measurement cycle. The light from the lamp is measured at the beginning and end of each current pulse after Lorentz line broadening and self-reversal have had time to fully develop. The difference between the absorbance signals observed at the two different sampling intervals is not influenced by either continuum absorption or light-scattering error signals. This approach is simple to implement, uses only standard light sources, possesses the same advantages relative to the conventional auxiliary continuum source lamp method of background correction as does the Smith and Hieftje approach, and has the added feature that all light measurements are made when the source lamp emission is very intense with respect to signals from extraneous light sources.

Specific Refractive Index Increment Measurements on Macromolecules Using a Waters R401 Differential Refractometer

Abstract An accurate and simple method for determining the specific refractive index increment, dn/dc, of synthetic polymers during size-exclusion chromatography has been developed using a modified Waters R401 differential refractive index (DRI) detector. The only modification required on the R401 involved the replacement of the standard white light source with a monochromatic source. The use of this instrument offers a number of advantages over more classical instruments and procedures normally employed in evaluating this parameter. The only requirement which must be met in order to successfully measure this parameter is the conservation of mass (in terms of the amount of polymer injected on to the columm and which passes through the DRI detector). However, in some cases, even this requirement may be relaxed. The application of this procedure will be demonstrated for several synthetic polymers in mixed and single solvent systems.

Flexible fiberoptics and pediatric otolaryngology. A simple technique for examination and photodocumentation.

Examination of the ears, nose, nasopharynx, hypopharynx, and larynx has been dramatically altered by the advent of flexible fiberoptic devices. The stunningly clear real visual images may be readily adapted for photography. Using a standard flexible fiberoptic nasopharyngolaryngoscope and standard light sources, standard cameras, and standard photographic processing, the author details a simple method for examination and photodocumentation in pediatric otolaryngology. Color transparencies, color prints, and color and sound videotapes may be produced which are consistently clear, color balanced, and have good depth of field.

Dispersed source for absolute calibrations

In the VUV spectral range, there exist only a few secondary standard light sources. To overcome the spectral and energetic restrictions of commercially available line lamps the intense continuum of a stabilized argon mini-arc transfer standard can be used between 160 and 350 nm. To perform spectrally resolved calibrations, it is then necessary to use filters or grating devices. The phase balancing method and the brightness conservation law have been used to optimize a stigmatic grating device which matches exactly the “étendue” of the source and which delivers well collimated output beams.

Calibration and error analysis of multiwavelength telephotometers

In preparation for the EPA-VISTTA summer 1979 field program, 12 multiwavelength telephotometers were tested and calibrated. A standard light source was used in the calibration process, and the linearity of the instruments was checked using neutral density filters. Calibration of the telephotometers was performed before and after this experiment to determine individual instrument response and drift. Results of the calibration indicated that the instruments had an average inherent error of approximately 1 per cent when operating in the contrast (or ratio) mode. The degree of error is less if a correction is made. In the absolute radiance mode, the instrument was estimated to have an average inherent error of approximately 10 per cent. Results of two of the telephotometer comparisons performed during the VISTTA program are shown to illustrate the problems of target selection and inhomogeneity. A comparison of the extinction coefficients determined from the telephotometers and the scattering coefficients measured by nephelometers showed reasonable agreement for the first example. A more comprehensive, side-by-side comparison showed that results from the two telephotometers agreed within 2 per cent in the ratio mode. However, the uncertainty in the extinction coefficient is between 10 and 15 per cent. This uncertainty can be reduced by eliminating the low contrast cases.

Fluorescence Bronchoscopy

A new method of fluorescence bronchoscopy is presented which uses a standard light source and a special filter combination to permit the carrying out of fluorescence bronchoscopy with a surface marking method by means of inhaling a fluorescein solution. Normal mucous membrane, or mucous membrane with no histological change other than inflammation, which is cleansed by ciliary activity, does not usually fluoresce for a period longer than about two hours after the inhalation. There were, it is true, 13 false positive fluorescence out of 52 fluorescing areas in the mucous membrane. Correctly recorded were 39 cases of positive, ie, visible tumors, metaplasias, accumulation of mucous glands in the epithelium, and mucous membrane which had undergone a neoplastic change in the sense of a lymphangitis carcinomatosa or a mucous membrane carcinosis; these all caused fluorescence. The false negative results amounted to only two nonfluorescing tumors and one metaplasia. These diagnoses arise from the first 100 patients examined by this method. the fact must be especially emphasized that out of the 58 carcinoma cases, there were 7 where neoplastic changes in the mucous membrane were diagnosed by the fluorescence technique, although they had not been recognized macroscopically either by the naked eye or by the Hopkins optical technique.

A psychometric approach to the measurement of color preference.

A three-part investigation was conducted to explore the meaning of color preferences. Phase 1 used a Q-sort technique to assess intra-individual stability of preferences over 5 wk. Phase 2 used principal components analysis to discern the manner in which preferences were being made. Phase 3 used canonical correlation to evaluate a hypothesized relationship between color preferences and personality, with five scales of the Personality Research Form serving as the criterion measure. Munsell standard papers, a standard light source, and a color vision test were among control devices applied. There were marked differences in stability of color preferences. Sex differences in intra-individual stability were also apparent among the 90 subjects. An interaction of hue and lightness appeared to underlie such judgments when saturation was kept constant. An unexpected breakdown in control pointed toward the possibly powerful effect of surface finish upon color preference. No relationship to five manifest needs were found. It was concluded that the beginning steps had been undertaken toward psychometric development of a reliable technique for the measurement of color preference.

Vacuum UV and soft x-ray optical emissions from electron impact on metals

Spectrograms from 2200 to 20 A of optical emissions produced by a simple lamp using fast (3-10-keV) electron impact on tungsten and tantalum targets are presented. The lamp dissipated up to 5 kW/cm(2) on the target surface, simultaneously cleaning the surface and generating bremsstrahlung in the soft x-ray region with 3-keV electron impact and longer wavelength transition radiation at the higher energy. In both the bremsstrahlung and transition radiation modes, the lamp emissions were of sufficient strength and reproducibility to qualify the two mechanisms as potential processes for use in a secondary standard light source. Calculated spectral distributions of transition radiation for normally incident electrons on tungsten, tantalum, and aluminum targets, with a viewing direction 45 degrees from the normal, are also shown.