Arbitrary Spectral Distribution Research Articles

Numerical determination of tristimulus values

I consider numerical methods for evaluating the tristimulus values of Pλ, an arbitrary spectral power distribution. Various classical quadrature rules are discussed, and numerically stable algorithms for their construction are presented. I introduce a new quadrature rule developed specifically for evaluating tristimulus values. The method involves the simultaneous generation of three quadrature rules sharing a common set of nodes that is optimal in a sense much like the optimality of the Gauss rules.

Color classification by vector subspace method and its optical implementation using liquid crystal spatial light modulator

Color classification by a statistical pattern recognition method, the subspace method, was implemented by a simple optical system including a liquid crystal spatial light modulator. Area coding filters corresponding to eigenvectors were drawn on the liquid crystal panel. The vector inner products between the filter functions of each class and the input spectral distributions were calculated instantaneously. To construct low-dimensional subspaces for each class, the recognition system for arbitrary spectral distributions was used and efficient classification filters were constructed after several iterative learning cycles. Samples with small hue differences were correctly classified.

Kinetics of furocoumarin photosensitization of DNA to near-ultraviolet radiation.

Abstract— The kinetics of DNA photoadduct formation induced by irradiation with near‐ultraviolet in the presence of furocoumarin photosensitizers has been analyzed for systems of differing repair competance and for light sources of arbitrary spectral intensity distributions. The results are exemplified by applications to published data on DNA photoadduct yields in vitro and in vivo and Escherichia coli survival curves.

Absorption spectrum of a driven atom in a perturber gas

A two-state atom in a perturber gas is irradiated by intense near-resonant radiation with an arbitrary spectral distribution. The author obtains an expression for the absorption spectrum of this system as measured by a weak probe field. The method is the same as applied before to derive the fluorescence spectrum of this system.

Receiver performance evaluation using photocounting cumulants with application to atmospheric turbulence

A new technique for evaluating optical communication system performance directly from the photocounting cumulants is presented. This technique is most useful in situations where exact, explicit, closed form solutions exist for the photocounting cumulants, but do not exist for the photocounting distribution, such as in the generalized case of communication through lognormal atmospheric turbulence. Using this technique, theoretical probability of error curves are presented for communication through lognormal atmospheric turbulence, for a superposed coherent-in-chaotic signal, embedded in additive independent Poisson noise, with arbitrary ratio of sampling time to source coherence time, arbitrary ratio of coherent to chaotic component, arbitrary mean frequencies of the coherent and chaotic components, and where the chaotic component need not be stationary and may have arbitrary spectral distribution. Since no solution exists for the photocounting distribution itself in this generalized case, the corresponding performance calculation has not previously been possible. The case described applies to the detection of radiation originating from a multimode laser or scattered from a rough target, and passing through atmospheric turbulence. A special case of these results is shown to be in excellent agreement with previous calculations [Rosenberg and Teich, Applied Optics12, 2625 (1973)] for a lognormally modulated coherent signal.

Resonance fluorescence in a weak radiation field with arbitrary spectral distribution

Abstract : The authors show that the laser bandwidth effects in resonance fluorescence at low intensities can be treated most readily in terms of simple convolutions, and further that this approach allows one to consider an incident field with an arbitrary spectral distribution, with or without the presence of atomic (line-brroadening) collisions.

Principles of the Generalized Spectroradiometry

The progress in the fields of radiation sources and their applications is remarkable nowadays. This naturally demands a substantial innovation in the field of spectroradiometry, the essential technique for the progress.The author succeeded in establishing new general principles in the spectral measurements of radia-tion, and accomplished a versatile system of spectroradiometry. This offers a powerful technical means to the fields of practical applications.The spectral measurement of radiation is a common procedure of obtaining the accurate results of weighted integrals through numerical integrations. Then, the demand for spectral decomposition is to be optimized with reference to the accuracy of the recomposed results. This problem is considered in two ways; as a demand for the slit width of monochromator and as a demand for the sampling intervals.Conclusions are summarized as follows:1. The fundamental condition to obtain properly the spectral information is to realize a conformity of sampling intervals to the slit widths.2. Concerning the photometry and colorimetry, the general standard to be applied to an arbitrary spectral distribution is the slit width of 2.5nm. Then, the whole visible spectrum is perfectly obtaina-ble as the values at 161 sampling points.3. When utilizing a prism monochromator, it is a reasonable way to apply the condition of mechan-ically constant slit widths and intervals. Then, the whole visible spectrum is also perfectly obtainable as the values at 161 sampling points.

Theory for radiatively driven harmonic acoustic waves in a confined gas

A detailed theoretical study is made of radiatively driven acoustic waves inside a closed cylindrical tube. The formulation accounts for all the essential phenomena for a gas in vibrational equilibrium—namely, gas motion, longitudinal and radial viscous dissipation, longitudinal and radial heat conduction, and radiative transfer with spectral detail included. An approximate expression is derived for the pressure response. This solution is applicable to arbitrary spectral distribution of the radiative absorption coefficient, under conditions attainable in the laboratory. The solution includes both tuned and untuned acoustic conditions as well as the spectrophone limit—that is, the condition where the length of the tube is much smaller than the length of the acoustic wave. The influence of spectral detail on the pressure response is illustrated by an example that employs a single Lorentz profile to represent an absorption band.

Exact First-, Second-, and Third-Order Photocounting Cumulants for Lognormally Modulated Mixtures of Coherent and Chaotic Radiation

In this paper we investigate the photocount statistics of mixed coherent plus Gaussian light that has suffered lognormal fading, such as produced by the turbulent atmosphere. The Gaussian component need not be stationary, may have an arbitrary spectral distribution, and the mean frequency of the coherent and Gaussian components need not coincide. The first three cumulants of the phototelectric counts for a single detector and for an array of detectors are obtained for arbitrary ratios of counting time to source coherence time, β, while assuming the fading to be fully time correlated over the detection interval. In particular, the cumulants are evaluated for Gaussian light of Lorentzian spectrum. The variation of the cumulants with degree of turbulence and detector separation is exhibited graphically, for several values of β, and ratio of coherent to chaotic component, y. The effect of increasing the degree of turbulence is shown to cause the ratio of the second-order cumulant for Gaussian light to the same cumulant for coherent light to approach a nominal value of 2, indicating the extent to which the fading dominates the counting statistics. As the detector separation is varied, the twofold cumulant exhibits the spatial correlations of the turbulence, when the source radiation alone is assumed to be approximately spatially coherent at the detector array. Furthermore, the cumulants are shown to increase exponentially with the turbulence level σ, the log-intensity standard deviation.

к тЕОРИИ пОглОЩЕНИь М ОЩНых пОтОкОВ ИжлУЧЕ НИь

The equations for a density matrix were used to calculate the radiation absorption of an arbitrary spectral composition and angular distribution. The calculation takes into consideration the saturation effect, the interaction of the absorbing molecues with the surroundings being described by means of the probabilities of non-optical transitions and not by means of approximate relaxation terms. The result are expressions for the absorption coefficient, taking into consideration its dependence on the intensity, spectral composition, direction of propagation and polarization of the radiation, which is absorbed in the region of one and the same absorption curve of the molecule. The relations also contain the dependence of the absorption coefficient on the intensity of the radiation absorbed in the region of other natural frequencies of the molecule and on all the probabilities of non-optical and spontaneous transitions.

Protective glasses for welding.

Measurements are described as a basis for specifications of protective glasses in welding operations. § 2 deals with measurements of the thresholds of ultraviolet and infrared radiation, which produce a just perceptible change in the eye. These measurements were carried out by Fischer, Ver-meulen and Eymers for monochromatic radiation. By means of a harm-factor the equivalent dose of radiation with an arbitrary spectral distribution is calculated. In § 3 measurements of the ultraviolet and infrared radiant flux in welding operations are described and the maximum permissible transmission factor in these spectral regions is determined. § 4 deals with measurements of the visible radiation and the maximum and minimum, values of the visible transmission factor. In § 5a comparison has been made with American, British and German Specifications.