Showing papers in "Journal of the Optical Society of America in 1957"
TL;DR: In this paper, the refractive index of standard air has been tabulated for the range 0.2 to 20.0 μ, namely, 0.8(0.1)2.
Abstract: The refractive index of standard air has been tabulated for the range 0.2 to 20.0 μ, namely, 0.2(0.01)0.8; 0.8(0.1)2.0; 2.0(0.5)10.0; 10(1)20 μ. The values are based on Edlen’s formula. For computations of Rayleigh scattering, the scattering cross sections, the mass and volume scattering coefficients have been tabulated for the same values of wavelength as for the refractive index. The optical thickness and the transmissivity of the standard atmosphere is given next, and finally, the mean scattering coefficient for visual observations which is βv=1.23×10−7 (cm−1).
467 citations
TL;DR: Difficulties encountered in applying immersion methods of refractometry to living cells because the choice of immersion media is very limited have now been overcome by the use of protein solutions.
Abstract: The development of phase contrast and interference microscopy has focused attention on the possibility of measuring the refractive indexes of living cells. Difficulties are encountered in applying immersion methods of refractometry to living cells because the choice of immersion media is very limited. These difficulties have now been overcome by the use of protein solutions. When the refractive index of the immersion medium matches that of the cell cytoplasm the latter becomes virtually invisible and phase contrast can be used as a sensitive null indicator to determine the match position. The refractive index is directly related to the concentration of cell solids and refractometry has been extensively used for measuring such concentrations in a variety of living cells. The concentration of water also follows immediately. Examples of the application of this method to retinal rods and cones, to the study of cell populations such as red blood cells, and to the investigation of the osmotic reactions of living cells are given. Other applications such as contrast variation in living cells, demonstration of chromosomes, and the spectrophotometry of clarified cell suspensions are briefly discussed.Interference microscopy can be used for the direct measurement of optical path difference and it is shown that this quantity is directly related to the dry mass per unit area. By combining interference microscopy and immersion refractometry it becomes possible to measure the cell thickness and hence to calculate dry mass and wet mass, volume, and water content of living cells. Examples of these methods are given and some of the limitations indicated.
300 citations
300 citations
TL;DR: In this paper, the infrared index of refraction data for single crystal germanium and silicon was presented for a modified selenium glass, and the data for the same type of glass was also presented.
Abstract: Infrared index of refraction data are presented for single crystal germanium and silicon. Also included are data for a modified selenium glass.
270 citations
TL;DR: In this paper, a new proof of the general interference law for partially coherent fields is obtained and is illustrated by simple and direct experiments, which show the changes in the visibility of the fringes as the degree of coherence varied and the results are compared with the predictions of the theory.
Abstract: Two-beam interference with partially coherent light is discussed. A new proof of the general interference law for partially coherent fields is obtained and is illustrated by means of simple and direct experiments. Photographs are given which show the changes in the visibility of the fringes as the degree of coherence varied and the results are compared with the predictions of the theory.
201 citations
TL;DR: In this paper, it was shown that radio-frequency resonance signals in the ground state can be used to detect radiofrequency resonance in optically excited atomic states, which can produce a characteristic change in intensity or in the degree of polarization of the light re-emitted.
Abstract: In the optical excitation of atoms with polarized light, producing excited atoms, only some of the Zeeman sublevels of the excited state are actually reached, so that large differences of population can be built up between Zeeman sublevels or between hyperfine structure (hfs) levels. This property can be used to detect radio-frequency resonance in optically excited atomic states. These resonances produce a characteristic change in intensity or in the degree of polarization of the light re-emitted. Zeeman intervals, Stark effects, and hfs intervals can be measured in this manner. (The Stark constant of the 63P1 level of Hg and the electric quadrupole moments of the alkali atoms have been obtained in this way.)The technique of “optical pumping” gives a way to concentrate atoms in some of the Zeeman sublevels of one of the hfs levels of the ground state.Atomic orientation has been obtained with the Na atom, in an atomic beam and in the vapor in equilibrium with the metal. The orientation effects have been studied by detection of radio-frequency resonance signals in the ground state. Orientation can be increased many times by adding a variable pressure of a foreign gas to the pure Na vapor. Because of the coupling between nuclear spin and electron spin, nuclear orientation is produced at the same time as atomic orientation.
174 citations
TL;DR: Measurements of light- and dark-adapted absolute thresholds were obtained from three pigeons at 15 wavelengths ranging from 380 mμ to 700 mμ, and photopic and scotopic functions are quite similar to those found in electrophysiological studies of the pigeon eye.
Abstract: Measurements of light- and dark-adapted absolute thresholds were obtained from three pigeons at 15 wavelengths ranging from 380 mμ to 700 mμ. Pecking responses caused a stimulus patch to fluctuate in intensity up and down across the pigeon’s threshold, and a record of the intensity provided the sensitivity data. The sensitivity of the birds was followed throughout a period of 80 min following a standard pre-exposure to white light. Four complete dark adaptation curves were obtained from each bird at each wavelength. Spectral sensitivity functions derived from these curves place the photopic maximum at 560–580 mμ, and the scotopic maximum at about 500 mμ. The scotopic function is fitted closely by aphakic human data. The photopic function shows inflections that may be related to similar inflections in corresponding human curves. The functions are quite similar to those found in electrophysiological studies of the pigeon eye. They also correspond rather well to the absorption spectra of chicken rhodopsin and iodopsin.
173 citations
TL;DR: In this paper, the authors introduced the concept of induced transmission and applied it directly to the problem of improving the efficiency of metal band pass filters, and the resulting designs were discussed from different points of view.
Abstract: The potential transmittance of a given absorbing film depends only on the load admittance of the optical structure with which it is backed, in addition to the optical parameters of the film itself. Utilizing appropriately designed backings of nonabsorbing multilayer films, admittances for light of a specified wavelength can be obtained which greatly increase the potential transmittance of certain materials, notably metals with high k/n ratios. A high transmittance of the specified monochromatic radiation results if the given film plus backing is subsequently antireflected by a second nonabsorbing multilayer combination added on the side of incidence. This procedure introduces the basic principles of “induced transmission.” These principles are applied directly to the problem of improving the efficiency of metal band pass filters. The resulting designs are discussed from different points of view.
153 citations
TL;DR: A mathematical discussion is presented of eye positions and eye movements in terms of quaternion theory, where an eye movement may be regarded as a rotation of the eye about an axis through the center of rotation.
Abstract: A mathematical discussion is presented of eye positions and eye movements in terms of quaternion theory. An eye movement may be regarded as a rotation of the eye about an axis through the center of rotation. The parameters of the axis of rotation and the extent of the rotation are associated to form a higher complex number, and this leads to the definition of an eye position in terms of the rotation by which it is reached from the prinary position. Equations are derived for the parameters of the single rotation equivalent to two successive finite rotations, for Listing’s law, for torsional movements, for the angle between the primary horizontal meridian of the eye and the plane of regard, and for the angle between the primary vertical meridian of the eye and the true vertical plane through the fixation line.
144 citations
TL;DR: In this paper, the authors compare the performance of successive matching and simultaneous matching and find that the successive matching is more common in everyday life whereas simultaneous matching is standard colorimetric practice.
Abstract: The two matching methods were compared to see whether they gave substantially different results. Such a difference would be of interest because successive matching is common in everyday life whereas simultaneous matching is standard colorimetric practice. An experiment was performed in which 25 test colors were matched by both methods. The successive or memory method yielded (1) the higher variability of replicative matchings, (2) the shorter matching times, (3) systematically higher purities, and (4) somewhat higher luminances. Three supplementary experiments are cited which are confirmatory with respect to the principal finding of extra purity and luminance usually required for the memory matches. This increased apparent strength of the remembered colors seems to be a direct consequence of the selectivity of memory.
135 citations
TL;DR: In this paper, an apparatus has been developed in two stages which permits optical studies to 200, 000 atmospheres pressure, using NaCl windows and a press suitable to fit in a spectrometer.
Abstract: An apparatus has been developed in two stages which permits optical studies to 200 000 atmospheres pressure. The use of NaCl windows permits studies in the near ultraviolet and in the infrared as well as in the visible. The design of the pressure cells and of a press suitable to fit in a spectrometer are described with essential dimensions. A calibration tested against Bridgman’s data to 87 000 atmospheres is given.
TL;DR: In this article, a general treatment of the influence of the size of the source on the visibility of the fringes in two-beam interferometers is given, together with some of the more immediate applications.
Abstract: The formulation of the theory of spatial (monochromatic) coherence is reviewed, together with some of the more immediate applications. These include the conditions for effectively coherent and incoherent illumination, the theory of stellar interferometry, and the interference microscope.A general treatment of the influence of the size of source on the visibility of the fringes in two-beam interferometers is given, together with applications. The use of coherence theory in microscopy is then summarized, and the influence of the numerical aperture of the illuminator is illustrated in special cases. These include the images of two close point apertures, a narrow slit, and a periodic structure. It is shown how the concept of an “effective source” facilitates the study of the influence of aberrations under different conditions of coherence.The paper concludes with a discussion of the theory of chromatic coherence.
TL;DR: In this article, two independent methods were used: direct spectrophotometry through the transparent windows of the atmospheric gases, and measurement of the number and diameter of the water droplets, followed by a Mie-theory calculation of the spectral transmittance.
Abstract: Two independent methods were used: direct spectrophotometry through the transparent windows of the atmospheric gases, and measurement of the number and diameter of the water droplets, followed by a Mie-theory calculation of the spectral transmittance Results from the two methods are in good agreement when the media are sufficiently homogeneous, as for a quiet haze or fog and artificial smokeThe following kinds of atmospheres were considered: hazes (optical density per km in the visible spectrum is less than 2); a small number of small-drop fogs (optical density per km less than 10); evolving fogs (which have changing distributions of drop-diameters); nonevolving, slightly selective fogs; artificial smokes In addition, some information is given on the statistical distribution of drop-diametersIt was found that the transmission of haze increased markedly with increasing wavelength, from the visible to 10 microns, but this marked increase was not found for fogs
TL;DR: Harmonic analysis reveals that, while individual accommodation/time curves show strong frequency bands, there are no characteristic frequencies either for an observer or for a stimulus situation.
Abstract: Accommodation is measured by flashing into one eye for 0.05 second every 10 seconds a beam whose configuration indicates whether the subject’s eye is over-accommodated, under-accommodated, or correctly accommodated for the measuring level. The exposure of the measuring beam is short enough not to contaminate the results with accommodative responses to it. Changes in accommodation can thus be followed by a bracketing procedure.The visual stimulus presented to the eye is an empty field, both a completely dark one and one with a bright central area without sharp contours. The eye responds to this kind of stimulation by a fluctuating level of accommodation, with an average level of a little over 1D and with peak-to-trough amplitude of the oscillations of up to 1D, the most prominent period of the fluctuations being about two minutes. Harmonic analysis reveals that, while individual accommodation/time curves show strong frequency bands, there are no characteristic frequencies either for an observer or for a stimulus situation.
TL;DR: The sensitivities of twelve normal observers to small color differences were determined by studying the distribution of color-matching errors about a color center in the chromaticity diagram.
Abstract: The sensitivities of twelve normal observers to small color differences were determined by studying the distribution of color-matching errors about a color center. Twenty-two color centers were used. These were distributed throughout the chromaticity diagram. The average luminance of the colors was 4.9 ft-L. The matching field size subtended 10° at the observer’s position. The remainder of the visual field was filled with a white surround. The data for the twelve observers are found to be in general agreement with previous experiments although some differences appear significant.
TL;DR: In this article, the spectral lines of an acetylene-air flame have been determined based on intensity-density graphs, constructed from photoelectric measurements of the total line intensities as a function of the density of the emitting atoms in the flame.
Abstract: Optical cross sections corresponding to spectral lines of Li, Na, K, Ca, Sr, Ba, Tl, Cu, Ag, Cr, Mn, Fe, Co, and Ni, emitted by an acetylene-air flame, have been determined. The evaluation of the cross section is based on intensity-density graphs, constructed from photoelectric measurements of the total line intensities as a function of the density of the emitting atoms in the flame.When the cross section corresponding to the line has been determined, the measured intensity-density curves yield the absolute values of the product Nf of the number of atoms in the flame capable of absorbing the line, and the oscillator strength for the line. If the f value for the line is known, the degree of dissociation of the element in the flame can be found. If the f value for the line is not known, the product Nf allows, in some cases, the evaluation of the absolute f value for the line; in other cases only a lower limit of the absolute f value can be obtained. The results are compared with those of previous investigators.
TL;DR: In this article, the authors used doubly passed gratings to remove higher orders from the infrared spectra and achieved a wave-number precision of 0.04-0.05 cm−1 in most spectral regions.
Abstract: High-resolution infrared spectroscopy with a small grating instrument has now been extended to wavelengths of nearly 200 microns. In the range 5–50 microns the achieved resolution was about 0.3 cm−1 or slightly better. Beyond 50 microns the resolution varied from 0.5 to 1.0 cm−1. No predispersive device was used, but filters, residual-ray reflections, selective chopping of radiation, and “off-blaze” use of the doubly passed gratings were employed to remove higher orders from the spectra. These devices are discussed briefly and their characteristics for the various spectral regions have been tabulated. Calibration has been carried out with higher orders of atomic emission lines and absorption lines of previously measured molecular spectra. Wave-number precision is estimated as about 0.04–0.05 cm−1 in most spectral regions. Performance of the spectrometers is illustrated by reproductions of the actual recorded spectra of water vapor at 1600, 300, and 200–55 cm−1, of ethylene and ammonia at 950 cm−1, of benzene at 673 cm−1, and of carbon disulfide at 400 cm−1.
TL;DR: In this paper, a new method has been devised for measuring refractive indexes of crystals in the visible and infrared region, where thermocouples with CaF2 or KBr windows have been used to detect the 10 c/s refracted beam.
Abstract: A new method has been devised for measuring refractive indexes of crystals in the visible and infrared region. In this method thermocouples with CaF2 or KBr windows have been used to detect the chopped (10 c/s) refracted beam. Single synthetic crystals of CdS and ZnS grown by the vapor phase method have been examined from their absorption cutoffs to 1.4μ. In comparing the results obtained, in the visible region, to the visual method of determining refractive indexes, the thermocouple detector method has duplicated these to within an index of refraction of ±0.001. For data extended to the infrared region it is found that the calculated results compare very closely with the experimental data. Index of refraction measurements may now be extended considerably into the infrared region being limited only by the sensitivity of the detector and the intensity of the transmitted monochromatic beam.
TL;DR: In this article, infrared atmospheric transmission from 0.5 μ to 15 μ is shown as measured over three horizontal paths of 1000 ft, 3.4 statute mi, and 10.1 statute mi.
Abstract: Infrared atmospheric transmission from 0.5 μ to 15 μ is shown as measured over three horizontal paths of 1000 ft, 3.4 statute mi, and 10.1 statute mi. The intense source, a 60-in. carbon arc searchlight, permits a resolution throughout of about 10 wave numbers. Work is continuing in an effort to obtain data taken under a wide range of atmospheric and meteorological conditions. The data presented here represent an average relatively clear winter day, a moderately dense fog and a snowstorm.
TL;DR: In this article, it was shown that these regions of increased intensity are mainly produced by the refraction of sunlight at the wavy surface, and that the depth at which intensity peaks reach a maximum is a function of the wave shape, trochoidal or sinusoidal, and wave dimensions.
Abstract: A common optical phenomenon observed in shallow water is the presence of bright lines or bands of light moving across the sea bottom at surface-wave velocity. It is shown that these regions of increased intensity are mainly produced by the refraction of sunlight at the wavy surface. The depth at which intensity peaks reach a maximum is shown to be a function of the wave shape, trochoidal or sinusoidal, and the wave dimensions. This depth increases as the wave becomes longer and flatter. Intensity peaks of up to six times the average intensity level are predicted to be theoretically possible.
TL;DR: A computational procedure is described for predicting the color appearance of everyday objects based on the known spectral character of the given object in relation to the appearance data presented here.
Abstract: Specifications are reported of colors which match in appearance with relatively complete adaptation to daylight, tungsten, and a third greenish illuminant. A computational procedure is described for predicting the color appearance of everyday objects. This procedure is based on the known spectral character of the given object in relation to the appearance data presented here. Certain implications for color vision theory are included.
TL;DR: Thresholds are determined at various short times before and after the onset of a 38-mL conditioning stimulus in the dark-adapted eye, and following six other levels of pre-adaptation.
Abstract: Thresholds are determined at various short times before and after the onset of a 38-mL conditioning stimulus in the dark-adapted eye, and following six other levels of pre-adaptation. An outstanding feature of the results is that under certain conditions thresholds decrease with increasing pre-adapting luminance. The results are considered to provide an indirect picture of on-responses in the visual system. The relation between “masking” associated with these on-responses and those effects attributable to photochemical bleaching is assessed and discussed.
TL;DR: A critical analysis of Garlick and Gibson's method based on a mathematical determination of the applicable temperature range and on experimental evidence shows that the trap depths obtained are lower than those found by other methods.
Abstract: A method proposed by Garlick and Gibson is often applied to determine the energy positions of traps in phosphors. A critical analysis of Garlick and Gibson’s method based on a mathematical determination of the applicable temperature range and on experimental evidence shows that the trap depths obtained are lower than those found by other methods. Especially the frequency-of-escape constants calculated subsequently contrast strongly to those determined by separate measurements.
TL;DR: In this article, the fraction of randomly polarized radiation scattered by a spherical particle into a unit solid angle in the direction θ can be represented by the equation f(θ)=14π+14π∑n=1∞anPn(cosθ), where Pn(Cosθ) are the Legendre polynomials.
Abstract: The fraction of randomly polarized radiation scattered by a spherical particle into a unit solid angle in the direction θ can be represented by the equation f(θ)=14π+14π∑n=1∞anPn(cosθ),where Pn(cosθ) are the Legendre polynomials. Values of the angular distribution coefficients, an, are presented for nonabsorbing spheres with an index of refraction of 1.33 at a series of values of the ratio of circumference to wavelength of 1, 2, 3, 4, 5, 6, 8, 10, 15, 20, 25, and 30. Application of the results is illustrated.
TL;DR: In this article, the authors used optical data taken from an aircraft in flight to study the apparent luminance of distant objects and the reduction of apparent contrast along inclined paths of sight through real atmospheres.
Abstract: Quantitative treatment of the apparent luminance of distant objects and the reduction of apparent contrast along inclined paths of sight through real atmospheres has been accomplished by means of optical data taken from an aircraft in flight. Sample data from a single flight are used to illustrate some of the principles involved. Correlation has been found between the humidity profile of the atmosphere and its optical properties.
TL;DR: In this paper, a method for the preparation of electrodeless discharge tubes containing very pure rare earth and heavy element halides is described, and the effect of changing vapor pressure of the metal in the discharge is discussed and representative spectra shown.
Abstract: A method is described for the preparation of electrodeless discharge tubes containing very pure rare earth and heavy element halides. Successful tubes have been prepared using Nd, Pm, Tb, U, Pu, Np, and Am. The effect of changing vapor pressure of the metal in the discharge is discussed and representative spectra shown.
TL;DR: In this paper, a method of evaluation of the optical cross sections, i.e., cross sections for broadening collisions between excited atoms and foreign molecules, from experimental intensity-density data is described.
Abstract: A method of evaluation of the optical cross sections, i.e., cross sections for broadening collisions between excited atoms and foreign molecules, from experimental intensity-density data is described. This method utilizes the analytical expressions of the asymptotes to the theoretical intensity-density curves at very low, and at very high densities of the emitting atoms. Only relative intensity measurements are necessary for the evaluation of the cross sections. An intensity-density graph for the Na5890 line is constructed from photoelectric measurements of the total line intensities, emitted from a Lundegardh-type acetylene-air flame. The optical cross section for sodium corresponding to this line is found to be 64 square angstroms. A brief discussion of the possibilities of utilizing this method for the determination of the degrees of dissociation of metal salts in the flame, or the evaluation of absolute and relative f values of the spectral lines is included at the end of the paper.
TL;DR: In this article, the authors measured the reflectance and transmittance of opaque titanium films at the wavelengths 0.436 μ, 0.546 μ,0.578 μ, and 0.650 μ.
Abstract: Measurements were made of the optical constants and of the reflectance and transmittance of titanium films evaporated onto fused quartz and glass. In order to prepare pure titanium films with normal density, all depositions were carried out at a pressure p 40 A/sec. The optical constants were determined by Drude’s polarimetric method from opaque films at the wavelengths 0.436 μ, 0.546 μ, 0.578 μ, and 0.650 μ. The reflectance values computed from n and k agreed well with the directly measured ones. The reflectance of titanium was measured from 900 A to 10 μ. 100 A to 300 A thick films of titanium were found to have quite uniform transmittance throughout the visible spectrum and can, therefore, be used as neutral density filters. Three optical principles were used to measure the oxidation of titanium in air. At room temperature the rate of oxidation of titanium was found to be almost equal to that of aluminum (about 35 A of oxide are formed in one month). With increasing temperature, however, the oxidation of titanium increases much more rapidly than that of aluminum.
TL;DR: In this paper, a study of the Zeeman effect of absorption lines of GdCl3·6H2O and its dependence on the orientation of the crystal has given the constants for the magnetic ellipsoids for the ground state and 11 excited states.
Abstract: A study of the Zeeman effect of absorption lines of GdCl3·6H2O and its dependence on the orientation of the crystal has given the constants for the magnetic ellipsoids for the ground state and 11 excited states. Evidence is presented for identifying the first three absorption groups as transitions from 8S to 6P7/2, 6P5/2, and 6I7/2. The magnetic observations were made at 77°K, 4.2°K, and 1.7°K and field-free spectra also taken at 195°K and 273°K. Very strong fluorescence is observed from the lowest excited state to the ground state.The magnetic axes are approximately but not exactly the same for all observed states. The direction of maximum susceptibility is not that of the twofold crystal axis but perpendicular to it. There are small but definite deviations from isotropic magnetic behavior for the ground state.
TL;DR: In this article, the authors measured the reflectance and transmittance of very thin reflecting and transmission films, i.e., films with a thickness d very small compared with the wavelength λ of the incident radiation.
Abstract: Equations are given for the reflectances, transmittances, and phase changes by reflection and transmission of very thin absorbing films, i.e., films with a thickness d very small compared with the wavelength λ of the incident radiation. The similarities and differences between very thin homogeneous and inhomogeneous films are discussed, and some experimental results obtained on very thin gold and chromium films are presented. We measured the reflectance and transmittance of these films as a function of the angle of incidence φ0 and of the state of polarization of the incident light. A new method is given for obtaining the optical constants of ionic crystals in the infrared. The optical properties of thick metallic films, with some new photometric methods for the determination of their optical constants, are discussed. The theory of the optical absorption of metals is briefly presented.