Showing papers in "Applied Optics in 1963"
TL;DR: The present status of our knowledge of the structure of the spectra of the rare earths is derived partly from experimental data of the emission spectra, which provides the energy level scheme in great detail but are difficult and laborious to analyze.
Abstract: The present status of our knowledge of the structure of the spectra of the doubly and triply ionized spectra of the rare earths is derived partly from experimental data of the emission spectra of the free ions which provide the energy level scheme in great detail but are difficult and laborious to analyze. For the lower levels knowledge of the structure comes from the crystal absorption and fluoresence spectra. In all cases approximate theoretical calculations of the energies are essential.
929 citations
TL;DR: The theory of three-dimensional optical storage lends support to Beurle’s proposed mechanism of information storage in the brain, and makes three- dimensional storage very suitable for associative memories.
Abstract: In photography, information is stored in a medium which is essentially two-dimensional. Three-dimensional optical storage is possible in semitransparent colored materials, like alkali halides with color centers. With the use of coherent light sources, like lasers, large amounts of information can be stored in the volume, and retrieved with little interference. The storage of information is accomplished by the formation of interference patterns between each two plane parallel waves. This paper develops the theory of this form of storage. It turns out that the information storage capacity is as if every little cube with sides equal to the wavelength of light acts as an independent information storage cell, and the essential noise in recovering this information is only the statistical fluctuation in the number of color centers in such a cube. The storage capacity is therefore of the order of 1012–1013 bits per cm3. The main property of this way of information storage is the appearance of a “ghost image,” partly but not completely analogous to the one described previously. This property makes three-dimensional storage very suitable for associative memories. The theory lends support to Beurle’s proposed mechanism of information storage in the brain.
565 citations
TL;DR: In this paper, a synthetic and a natural prism of calcium fluoride were fitted to a three-term Sellmeier dispersion formula of the form: n2 − 1 = ∑Ajλ2/(λ2 − λj2).
Abstract: This paper gives refractive-index values at 24°C for a synthetic and a natural prism of calcium fluoride. Measurements were made by the minimum-deviation method at 46 calibrated wavelengths from 0.23 μ in the ultraviolet to 9.7 μ in the infrared. The indices of the synthetic prism were fitted to a three-term Sellmeier dispersion formula of the form: n2 − 1 = ∑Ajλ2/(λ2 − λj2). Dispersive quantities were computed which estimate the expected relative dispersion, chromatic aberration, and resolution of CaF2 as a function of wavelength. Values of dn/dt are also given. The results of this work are compared with previously reported data.
267 citations
TL;DR: In this paper, the National Bureau of Standards has made available a new standard of spectral irradiance in the form of a 200-W quartz-iodine lamp with a coiled-coil tungsten filament operating at about 3000°K and calibrated over the spectral range of 0.25 to 2.6 μ.
Abstract: The National Bureau of Standards has made available a new standard of spectral irradiance in the form of a 200-W quartz-iodine lamp with a coiled-coil tungsten filament operating at about 3000°K and calibrated over the spectral range of 0.25 to 2.6 μ. The calibration of this standard is based upon the radiance of a blackbody as defined by the Planck law of radiation, since it was done by comparisons with the NBS standards of spectral radiance, of luminous intensity, and of total irradiance, each of which was established through the use of blackbodies. This standard is used without auxiliary optics. Because of its small physical size and high operating temperature, relatively high spectral irradiances may be obtained through its use.
227 citations
TL;DR: In this article, the authors developed the theory of the filter in the focal plane whose transmission at each point is proportional to the intensity of the light from the object, which can be used in principle for recognizing and locating a small fragment in the original object.
Abstract: The analogy between electronic filters or networks and optical filters placed in the focal plane of an imaging arrangement has drawn attention to the potentialities of optical arrangements for information processing. This paper develops the theory of the filter in the focal plane whose transmission at each point is proportional to the intensity of the light from the object. This intensity filter—in imaging arrangements using coherent light sources—has the property of forming a “ghost image” of the whole object, when only a small fragment of the original object is shown. This ghost image can be utilized in principle for recognizing and locating a small fragment in the original object.
142 citations
TL;DR: The PEPSIOS spectrometer as mentioned in this paper is a short-range scanning instrument consisting of an interference filter and several simultaneously pressure-swept Fabry-Perot etalons in series.
Abstract: A description is given of the design principles, structure, and use of the PEPSIOS (trade mark) spectrometer, a versatile, easily portable, purely interferometric, high resolution short-range scanning instrument consisting essentially of an interference filter and several simultaneously pressure-swept Fabry–Perot etalons in series. In the study of a continuum, where it was necessary to isolate a single order, it has exhibited a luminosity 102 as great as that of a comparable modern grating-etalon combination instrument at the same resolution and is considerably lighter, smaller, and mechanically more stable. Although designed primarily for the photoelectric measurement of the total flux through an axial zone, the instrument has the property of producing a two-dimensional spatially resolved image at high spectroscopic resolution.
136 citations
TL;DR: In this article, a simple optical system consisting of two small lenses can be designed to take the place of a large flat in testing paraboloidal mirrors, and the procedure for computing such a null corrector and the accuracy required in its manufacture and use are discussed.
Abstract: A simple optical system consisting of two small lenses can be designed to take the place of a large flat in testing paraboloidal mirrors. Other aspheric concave mirrors can also be tested in this manner. The procedure for computing such a null corrector and the accuracy required in its manufacture and use are discussed.
124 citations
TL;DR: A specific example reveals how intricate automatic computing programs for optical design can become, and the problem consists of solving sets of simultaneous nonlinear equations in a space of thirty or more variables limited by prescribed boundaries.
Abstract: Automatic computing methods are being increasingly applied to optical design, and the development of programs for this purpose forms an interesting chapter in optical history. Mathematically, the problem consists of solving sets of simultaneous nonlinear equations in a space of thirty or more variables limited by prescribed boundaries. Although these boundary conditions do not basically alter the mathematics, they greatly complicate the resulting program, and a specific example reveals how intricate such programs can become. The full impact of automatic methods has not yet been felt, but one result should be to shift the attention of the lens designer from the detailed correction of aberrations to the problem of securing a proper compromise between the system requirements and the conditions for sharp imagery so that better balanced optical instruments may result.
116 citations
TL;DR: The use of properly designed light pipes to redistribute the energy of a solar furnace or an arc imaging furnace is discussed in this article, where the principle of operation, as well as formulas for estimating the flux uniformity and reflection losses are discussed.
Abstract: The use of properly designed light pipes to redistribute the energy of a solar furnace or an arc imaging furnace is discussed. Compared to alternate schemes of obtaining uniform irradiation over a large area, the light pipe has the advantage of good uniformity without a serious loss of efficiency. Theoretical analyses concerning the principle of operation, as well as formulas for estimating the flux uniformity and reflection losses, are discussed. The results also indicate that the only suitable cross sections are the square, triangular, hexagonal, and rectangular. Other cross sections, including the circular, are not satisfactory unless used with diffusely reflecting surfaces.
85 citations
TL;DR: In this article, a two-dimensional set of alternately transparent and nontransparent zones, the limit curves of which are regularly assembled equilateral hyperbolas having common asymptotes, is used to obtain a gain of luminosity greater than 100.
Abstract: A gain of luminosity greater than 100 is obtained by replacing the entrance and exit slits of a spectrometer by a two-dimensional set of alternately transparent and nontransparent zones, the limit curves of which are regularly assembled equilateral hyperbolas having common asymptotes. One of the asymptotes is parallel to the slits of the conventional spectrometers. The general construction and, to some extent, the handling qualities of conventional spectrometers are not altered. The Littrow-type mounting is particularly advantageous. The examples of the results mentioned have been obtained with an apparatus having a focal length of two meters using the single-beam and single-pass principle.
83 citations
TL;DR: In this paper, a new method is described for graphically representing the first-order layout of any optical system of axially symmetric refracting or reflecting surfaces, where the actual path of an arbitrary paraxial skew ray traversing it, provided the value of the Lagrange invariant is also known.
Abstract: A new method is described for graphically representing the first-order layout of any optical system of axially symmetric refracting or reflecting surfaces. Such a system can be uniquely defined by the actual path of an arbitrary paraxial skew ray traversing it, provided the value of the Lagrange invariant is also known. This paper describes some interesting properties of the diagram obtained by projecting the ray onto the object plane. The diagram has proved to be a very useful aid in first-order design, particularly in systems where lens diameters and locations are severely constrained.
TL;DR: In this paper, the authors reviewed the history of achromatic lenses and proposed the superachromat, which is corrected for four colors, including red, green, blue, and gold.
Abstract: The history of achromatic lenses is briefly reviewed. The latest development is the superachromat, which is corrected for four colors. Since the dispersion of glass can be represented by an equation containing four constants, the superachromat is practically corrected for all colors. The application of the superachromatic principle to thick lenses is described and it is shown that a compound lens can be made superachromatic by making each of its separate components superachromatic.
TL;DR: In this paper, an intense Hopfield continuum with relatively stable average intensity with time, few superimposed emission lines, and low scattered light, has been obtained in the 600-1100 A region from a helium gas discharge.
Abstract: An intense Hopfield continuum having relatively stable average intensity with time, few superimposed emission lines, and low scattered light, has been obtained in the 600–1100 A region from a helium gas discharge. A mild condensed gas discharge produces the continuum at an optimum pressure of about 40 mm Hg. The discharge circuit contains an external series spark gap, which is air blown and irradiated with a mercury lamp to improve its stability. After warm-up, the slow drift in intensity of the system over 4 hr is about 3%. Details of construction and operation are discussed, and initial results showing the use of this source to obtain absorption coefficients of gases by photoelectric scanning are presented.
TL;DR: In this paper, it was found that the available optical media do not permit a significant reduction in the scattered light in the ordinary coronagraph, and the reflecting coronagraph and the simple, externally occulted coronagraph can be made freer of scattered light by from one to more than two orders of magnitude, respectively.
Abstract: The development of balloon and rocket vehicles provides opportunity for nearly continuous observation of those parts of the solar corona remote from the sun. This opportunity places new requirements on the freedom of the coronagraph from scattered light. Several possible means of improving the coronagraph are described. It is found that the available optical media do not permit a significant reduction in the scattered light in the ordinary coronagraph. The reflecting coronagraph and the simple, externally occulted coronagraph can be made freer of scattered light by from one to more than two orders of magnitude, respectively, than the Lyot coronagraph. The use of the apodized, external, occulting disk developed by several investigators can reduce the scattered light by at least three orders of magnitude so that the instrumental background is similar to the skylight encountered during total eclipse.
TL;DR: In this article, it was shown that a light beam can be modulated simultaneously with two independent signals in the form of mutually perpendicular fields both transverse to the light beam and the signals are recoverable at the receiver by photodetectors responding to appropriate polarization components of the beam.
Abstract: Analysis of the linear electro-optic effect in crystals of classes containing a threefold rotation axis is carried out. It is shown that such crystals display a dual transverse electro-optic effect in which the magnitude of an electric field transverse to the light direction controls the electro-optic retardation and the direction of the field controls the orientation of the fast and slow polarization axes. The most desirable crystals for utilization of this effect are those of cubic class
4¯3m since they are optically isotropic in zero field and are not optically active. Using a crystal of this type, for example, zinc sulfide, analysis shows it is possible to modulate a light beam simultaneously with two independent signals in the form of mutually perpendicular fields both transverse to the light beam. The signals are recoverable at the receiver by photodetectors responding to appropriate polarization components of the beam. If the fields applied to the crystal consist of appropriate combinations of the modulating signals, the latter appear as upper or lower sidebands of the optical carrier. Differences of the polarization states of sidebands and carrier make it easily possible to achieve single-sideband suppressed-carrier transmission. Receiver design for superheterodyne detection of such signals is described. Results of experiments are given demonstrating the modulation and reception techniques described.
TL;DR: In this article, a double-pass NaCl prism was used to analyze the transmission coefficients for the selective absorption and for the continuous extinction of the infrared spectrum, over the range 1.0-12.5 μ.
Abstract: Infrared solar spectrum observations taken on 12 January 1955, in Denver, Colorado, with a double-pass NaCl prism have been analyzed for transmission coefficients for the “selective” absorption and for the “continuum” extinction. The analysis was performed over the range 1.0–12.5 μ. The good ness of fit for the average transmission for a random band model and for a regular band model is given for each of 203 data points distributed throughout the spectrum.
TL;DR: In this article, an angle measuring interferometer of the Michelson type, constructed for use primarily with a gamma diffraction spectrometer, is described, which has a sensitivity of 0.1 sec of arc on a measuring range of 30 deg, is designed with plane mirrors as end reflectors and a cube corner prism as the movable unit.
Abstract: S>An angle measuring interferometer of the Michelson type, constructed for use primarily with a gamma diffraction spectrometer, is described. The interferometer, which has a sensitivity of 0.1 sec of arc on a measuring range of 30 deg , is designed with plane mirrors as end reflectors and a cube corner prism as the movable unit. The interferometer operates with a continuously varying glass compensation. Several geometrically different arrangements of the components are possible. (C.E.S.)
TL;DR: A method of semiautomatic optical designing previously described has been developed further on a faster electronic digital computer and with increased machine speed, it has become possible to explore the nature of the process of convergence to an optimum design.
Abstract: A method of semiautomatic optical designing previously described has been developed further on a faster electronic digital computer. The new programs embody comprehensive controls of boundary conditions and are more fully automatic in operation. With these refinements and increased machine speed, it has become possible to explore the nature of the process of convergence to an optimum design.
TL;DR: In this paper, the influence of the source, background, noise, counting time, and other parameters on the optimum transmittance was considered and the best value of the transmissance depends upon numerous parameters and varies between 2% and 90%.
Abstract: Beer’s law is used widely in the determination of cross sections and of unknown solution concentrations in the form τ = 10−A, where τ is the transmittance and A is the absorbance. By the criterion of minimum experimental error, the best value of the transmittance depends upon numerous parameters and varies between 2% and 90%. This paper considers the influence of the source, background, noise, counting time, and other parameters on the optimum transmittance.
TL;DR: The significance, limitations, and advantages of this tool for image evaluation are discussed along with some suggestions of direction along which future work may be carried as mentioned in this paper, from the point of view of an individual interested in the design, fabrication, evaluation, and use of large systems of very high precision.
Abstract: Evaluation of photographic optical systems through use of the optical transfer function or sine wave response has become commonplace. The fundamental physical concepts which lie behind the theory are not, however, widely known and are outlined for use by the optical engineer. The significance, limitations, and advantages of this tool for image evaluation are discussed along with some suggestions of direction along which future work may be carried. The discussion is from the point of view of an individual interested in the design, fabrication, evaluation, and use of large systems of very high precision.
TL;DR: The results of these experiments are compared with previous data obtained from other Raman and inelastic neutron scattering experiments to determine fundamental lattice vibrations of these crystals as mentioned in this paper, which are observed to combine with the OH− stretching vibrations to produce the complex absorption spectra near 2.7 μ.
Abstract: The infrared absorption spectra from 700 to 75 cm−1 of Mg(OH)2, Mg(OD)2, Ca(OH)2, and Ca(OD)2 are presented. These spectra were obtained from powders dispersed in polyethylene. In addition, the results of a Raman scattering experiment performed on a single crystal of Mg(OH)2 are presented. These results indicate four lines corresponding to the four predicted symmetric modes. The results of these experiments are compared with previous data obtained from other Raman and inelastic neutron scattering experiments to determine fundamental lattice vibrations of these crystals. Many of these lattice vibrations are observed to combine with the OH− stretching vibrations to produce the complex absorption spectra near 2.7 μ.
TL;DR: In this article, temperature coefficients for photomultiplier tube types used in astronomy were reported for 1% stability of gain and color response, which is nearly an order of magnitude better than what is usually achieved at the telescope.
Abstract: Temperature coefficients are reported for photomultiplier tube types used in astronomy. For 1% stability of gain and color response, temperature regulation of 1°C or better is generally required. This is nearly an order of magnitude better than what is usually achieved at the telescope, but careful use of a well-designed cold box should make 1°C temperature stability possible. For maximum stability and reproducibility, ordinary blue-sensitive tubes should be avoided at wavelengths longer than 5000 A, and trialkali cathodes should not be used beyond 6500 A.
TL;DR: In place of the regular column by Mr. Cooke, this month the authors are running a short review of one British company’s optical activities, prepared by Their Man in England, George Fishter.
Abstract: When making a very flat highly polished chopper wheel of stainless steel polished on both sides, we-and many others-find that it warps like a potato chip if such a chopper is polished one side at a time. Our solution is to lap and polish both sides at the same time so that stock removal is bilateral and warping from one side to the other is precluded.
TL;DR: In this article, an apparatus is described for testing photomultiplier tubes to be used in an astronomical spectrophotometer, and the results of these tests are presented, together with specific data for cells including relative-sensitivity scans of photosurfaces.
Abstract: An apparatus is described for testing photomultiplier tubes to be used in an astronomical spectrophotometer. The wide differences in residual nonthermal dark current (after refrigeration) found among photomultiplier tubes with very similar rated characteristics require that each cell intended for faint-light astronomical applications be individually selected. The better CsSb and trialkali tubes which we tested have residual dark currents extrapolated to zero bias respectively in the range 2–6 and 15–30 counts/sec; unfortunately this residual component is usually also somewhat nonstatistical in character. Further general conclusions from our tests are presented, together with specific data for cells including relative-sensitivity scans of photosurfaces.
TL;DR: In this article, the reflection and transmission of fifteen commonly used infrared optical materials have been measured to 50 μ with a Beckman IR-7 with CsI optics, and small inexpensive reststrahlen filters have been constructed.
Abstract: The reflection and transmission of fifteen commonly used infrared optical materials have been measured to 50 μ with a Beckman IR-7 with CsI optics. Using these reflection properties, small inexpensive reststrahlen filters have been constructed. By applying a fine grind to reststrahlen plates, it is shown that stray light can be reduced in far-infrared instruments.
TL;DR: In this paper, the authors calculate the Raman output power as a function of time and its spectral content when a Raman active material is placed inside the optical Fabry-Perot cavity resonator of a giant pulse (Q-switched) laser.
Abstract: When a Raman active material is placed inside the optical Fabry-Perot cavity resonator of a giant pulse (“Q-switched”) laser, the high-power laser light pulse induces gain in the Raman material at frequencies shifted from the giant pulse frequency by well-known Raman frequencies. If this gain is large enough to overcome cavity losses, a strong buildup of coherent light at the shifted frequency(s) may ensue; the process is analogous to stimulated fluorescence and is an example of stimulated Raman scattering. We calculate here the Raman output power as a function of time and its spectral content when the Raman material is in the laser cavity. From the resulting expressions (which contain no undetermined parameters) we calculate the properties of the light generated by nitrobenzene inside a giant pulse ruby laser and find that the results agree with (as yet incomplete) observations that have been made on that system.
TL;DR: In this article, the authors derived expressions for the relative amount of pumping radiation transferred from a cylindrical source to a laser by means of a reflector in the shape of an elliptical cylinder.
Abstract: Expressions are derived giving the relative amount of pumping radiation transferred from a cylindrical source to a cylindrical laser by means of a reflector in the shape of an elliptical cylinder. The general expression depends upon the radii of the source and laser, the eccentricity of the ellipse and the length of its semimajor axis, and an arbitrary angular distribution of source radiation. The effect of radiation reflected back into the source itself (source-blocking) is also considered. A very considerable simplification in the calculation results when the source distribution is invariant under a rotation of the source about its axis, i.e., when the distribution depends only on the direction of the radiation with respect to the local normal, thus corresponding to virtually all practical cases. Moreover, the special case of a Lambertian source distribution yields efficiencies which may be evaluated directly. Especially simple and illustrative is the Lambertian source which is sufficiently small compared to the reflector that source-blocking can be ignored.
TL;DR: In this paper, a program of polarimetry and photometry is described, where wide-band filters have effective wavelengths between 3250 A and 9900 A. Astronomical telescopes and a differential polarimeter are used with calibration by a Lyot depolarizer.
Abstract: Preliminary results are described of a program of polarimetry and photometry. Astronomical telescopes and a differential polarimeter are used with calibration by a Lyot depolarizer. The wide-band filters have effective wavelengths between 3250 A and 9900 A. The problems of instrumental polarization and depolarization are discussed; most of the instrumental effects can be avoided by proper aluminization of the telescope mirrors. The multiple molecular scattering of the sunlit sky and of the poles of Jupiter is closely represented by the Rayleigh-Chandrasekhar theory; the optical depth at the Jovian poles is 0.4–0.8. The same particle sizes that explain the interstellar reddening, 0.05–0.3 μ, are found from the interstellar polarization. Strong polarization-wavelength dependence is found for Venus and for lunar regions, but the detailed explanations require extension of the wavelength range. The range of wavelengths will be extended by using high-altitude balloons and spacecraft.