Spectral Radiance Factor Research Articles

Research on ClO2 as a Fluorescence-Reducing Agent: A Simple Method to Evaluate the Treatment Effect Based on Color Measurement

The reducing effects of fluorescent whitening agent-treated cotton under the action of chlorine dioxide were studied. Various factors were studied, including pH value, temperature, ClO2 concentration, and treating time. Furthermore, a simple method to evaluate the effect of fluorescence-reducing agent (ClO2) was proposed. By measuring the spectral radiance factor of the samples, the total absorption energy, total emission energy, and fluorescence quantum efficiency were calculated. It is demonstrated that fluorescence quantum efficiency could be used as a criterion to judge the fluorescence-reducing effect of ClO2.

Comparison measurements of 0∶45 radiance factor and goniometrically determined diffuse reflectance

A comparison between the absolute gonioreflectometric scales at the Helsinki University of Technology (TKK) and the Physikalisch-Technische Bundesanstalt (PTB) has been accomplished. Six different reflection standards were measured for their 0:45 spectral radiance factor between 250 and 1650 nm in 10 nm intervals. Also, the 0:d reflectance factor between 400 and 1600 nm in 100 nm intervals was determined from goniometric reflectance measurements over polar angles with subsequent integration within the hemisphere above the sample. Goniometric comparisons covering such an extensive wavelength range and also several different sample materials are rarely implemented. For all but one sample, the difference between the results obtained at the TKK and the PTB was, with the exception of a couple of measurement points, within the expanded uncertainty (k = 2) of the comparison at least up to a wavelength of 1400 nm. All differences between the measurement results can be understood, except for one translucent sample in the visible wavelength range. The effect of sample translucency was found to be significant in the NIR wavelength region. Also, a general tendency of an increase of the TKK values relative to the PTB values in the UV region was observed. Possible causes for this phenomenon are discussed.

New method for measuring an optical property of a sample treated by FWA

AbstractIn this article, a new method for measuring a total spectral radiance factor of a FWA‐treated sample illuminated by a specific standard illuminant is introduced. The method replaces an unstable real fluorescent standard by a bi‐spectral luminescent radiance factor data, which works as a virtual fluorescent standard (VFS) by knowing spectral intensity distributions of illuminations applied to the sample. The method utilizes two illuminations I1 and I2 whose relative spectral intensity distributions are different from each other and synthesizes a virtual illumination presenting the identical fluorescent spectral radiance factor to that presented by the standard illuminant with the VFS of the specific bi‐spectral luminescent radiance factor by linearly combining I1 and I2 with the suitable weighting factors. The applicability of the method is examined in principle by comparing ISO brightness and CIE whiteness index of fluorescent standard paper as a test sample obtained by this new method to the assigned values. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 195–200, 2007

Correlation recognition of objects from multispectral data

A formalized description of the process of forming and processing spectral patterns in multispectral optoelectronic observation systems is given. The spectral radiance factors are given for various objects, along with the results of calculations of the recognition criterion for various observation conditions. A preliminary analysis has been carried out of the possibilities of correlation-extremal recognition of terrestrial industrial installations on the basis of the multispectral data that have been obtained. © 2004 Optical Society of America

Quantum efficiency of fluorescent dyes in cloth

Based on an additional hypothesis of the Kubelka‐Munk theory, different equations describing the propagation of fluorescent light in cloth are proposed and a much simpler formula relating to the quantum efficiency of fluorescent dyes with spectral radiance factor is obtained. The polyester, wool and cotton samples were dyed with disperse and acid fluorescent dyes in the laboratory. With the spectral radiance factor of fluorescent samples measured via the two‐mode method, the quantum efficiencies are evaluated in terms of the new formula. These show good agreement to quantum efficiencies calculated using an alternative formula.

Spectral estimation and color appearance prediction of fluorescent materials

Bore-Kuen LeeFeng-Chi ShenChung-Hua UniversityDepartment of Electrical Engineering30 Tung ShiangHsinchu City 300TaiwanE-mail: bklee@chu.edu.twChun-Yen ChenIndustrial Technology Research InstituteOpto-Electronics and SystemsLaboratoriesBuilding 51, 195-8Section 4Chung Hsing RoadHsinchu County 310TaiwanAbstract. We present a low-cost, efficient, and industrially acceptablemethod to estimate the reflected and fluorescent spectral radiance fac-tors of a fluorescent object based on spectrophotometric data withoutusing a monochromator. With the measured spectral data, the coeffi-cients of the truncated Fourier series used to approximate these twospectral radiance factors are estimated using a weighted least squarealgorithm. The weighting function is defined as the sum of the CIE 1931standard x¯, y¯, and z¯color matching functions, so that the color differ-ence is minimized from the viewpoint of human vision. Three fluorescentsamples are used to verify our algorithm by predicting their color appear-ances under different sources.

Spectrophotometer CM-3630

Minolta has developed a new spectrophotometer CM-3630 for pulp and paper having several unique features. Specially its new technology for the adjustment of the relative UV content in the illumination, called NUVC (Numerical UV control), enables the instantaneous adjustment with no moving part, while a traditional Gaertner-Griesser method, in which a UV eliminating filter is mechanically inserted to the optimal position in the flux for the desired relative UV content, requires a time-consuming procedure. Beside this advantage, NUVC enables the UV adjustment not only for a single index such as ISO brightness or CIE Whiteness but also for both CIE Whiteness and Tint and even for Total Spectral Radiance Factor from which all colorimetric indices are derived.

Metrology of fluorescent retroreflective materials and its relationship to their daytime visibility

This paper describes aspects of fluorescence that relate to high-visibility retroreflective materials used for visual signaling and markings. Full colorimetric characterization of these materials requires separation of the fluorescent and non-fluorescent components. Quantification of the individual components allows for accurate prediction of performance under the various conditions of illumination and viewing encountered in practical applications. When measuring retroreflective materials, it has been found that measurement geometry has a significant influence on the reflected spectral radiance factors. For fluorescent retroreflective materials, the reflected component is more sensitive than the fluorescent component to geometric restraints. Therefore, geometric specifications and tolerances are critical in the measurement of these materials. Assessment of the relative visibility and conspicuity of fluorescent materials requires an understanding of the relationship between the spectral illumination and the total luminance factor of the specimen. Precise calculation of the total luminance factor under the varying conditions of illumination encountered in outdoor signing and marking applications is possible using the complete bispectral radiance factor array. The relationship between calculated results and field measurements is described. For routine quality control and material specification a more abridged metrology making use of the fluorescence luminance factor ( Y F) has been found useful. Y F for CIE illuminant D65 can be used to assess the fluorescent content and durability of fluorescent materials used in signing applications. Y F has also been found to correlate with the increased visibility performance of fluorescent signs under poor daytime visibility conditions. The introduction of Y F into materials specifications is beginning to take place.

Design and testing of a two-monochromator reference spectrofluorimeter for high-accuracy total radiance factor measurements

A two-monochromator reference spectrofluorimeter has been developed at the National Research Council of Canada in accordance with International Commission on Illumination and American Society for Testing and Materials colorimetry standards to permit high-accuracy total spectral radiance factor measurements of fluorescent materials. This fully automated instrument employs a xenon-arc light source, all-reflective optics, two grating monochromators with order-sorting filters, a cooled photomultiplier tube analyzing detector, and a calibrated silicon photodiode monitor detector. The instrument operating range is 250-1050 nm with a selectable bandpass (optimized for a 5-nm resolution), and the measurement geometry is 45 degrees annular illumination and 0 degrees viewing (45/0). We describe the instrument's design, testing, and verification procedures. Systematic errors that have been determined and corrected for include instrument polarization, beam nonuniformity, wavelength shifts, stray light, and system drift. The wavelength accuracy and reproducibility are estimated to better than +/-0.1 and +/-0.03 nm, respectively. The photometric short-term repeatability and long-term reproducibility are estimated to be better than +/-0.15% and +/-0.5%, respectively. The overall photometric accuracy is better than 1% of the value over a wide range of reflectances, and the reproducibility of the color specification of a fluorescent material is better than 0.25 DeltaE(ab) units.

Colorimetry of durable fluorescent retroreflective materials

AbstractThe development of durable daylight fluorescent retroreflective sheetings has led us to investigate some of the factors that influence color measurement of these materials. the colorimetry of retroreflective materials is particularly sensitive to measurement geometry. the added aspect of fluorescence increases the spectral uncertainties, making appearance measurements even more difficult. the visual properties used to describe fluorescent retroreflective materials should include chromaticity, lightness, peak spectral radiance factor, nighttime color, and color stability on exposure. A number of test methods exist for these measurements; however, practical experience in applying these methods to fluorescent materials shows significant variation in the resulting measured values. Colorimetric measurements on commercial instruments using 45/0 (0/45) geometry, a simulated D65 illuminant, and the CIE 2° standard observer yield results that are inadequate for precise quality control of durable fluorescent retroreflective materials. the uncertainty can be reduced by the use of transfer standards, provided that the standard is similar to the sample in both hue and fluorescent emission. Ultimately, the wide availability of commercial 2‐monochromator spectrocolorimeters will be required. © 1995 John Wiley & Sons, Inc.

Match prediction of highly fluorescent colors

AbstractColor formulation of fluorescent materials is not feasible with the usual methods used for nonfluorescent colors. Realizing the need for certain textiles that are dyed with fluorescent colorants, a technique was developed based on using certain dual‐monochromator measurements of the spectra of fluorescent colorants. to accomplish this formulation, a new spectral quantity independent of illuminant was developed for all fluorescent colorants. This is termed RELEX, which describes the relative excitation of the colorant. When this quantity is weighted by the spectral power distribution for a specific illuminant and factored for absorption by all ingredients in a mixture of colorants, the proper fluorescent emission is obtained, which can be added to the spectral reflected radiance factor, βs, for that mixture. Consequently, match prediction can be done for spectral radiance factor, βT, curves of fluorescent materials using an iterative estimation algorithm.

歯の色彩学的研究 歯肉および歯髄が歯冠の発色に及ぼす影響

Effects of the gingiva and pulp on natural teeth color were studied in order to determine the mechanism of crown coloring. Namely, teeth color was measured in 30 left maxillary central incisors of young subjects using a spectroradiometer under the following 4 different conditions:(1) free from artificial matters, (2) wearing of a masking plate, (3) undergoing infiltration anesthesia, and (4) simultaneous loading of (2) and (3).The results obtained are as follows:1. In the cervical area, the gingiva showed a greater effect than did the pulp.2. In the middle area, the pulp showed a little effect, but the gingiva exercised practically no effect.3. In the incisal area, neither gingiva nor pulp influenced teeth color.4. These results revealed that the spectral radiance factor of a natural teeth increased as the wavelength increased, showing a characteristic inflection point at about 580 nm, and that the gingiva and pulp had different effects on crown coloring among different areas.

Visible and near IR albedo measurements of ice/dust mixtures

The surface energy budget is an important input parameter for modelling the dynamical processes of the KOSI samples. In order to calculate the absorbed fraction of the irradiation the directional‐hemispherical albedo of the samples must be known. The albedo is calculated from the spectral radiance factor in the wavelength range from .36 μm to 2.5 μm. All samples were analysed before and after the experiments. The spectra of the experiments KOSI 3,4 and 6 have been measured under three different illumination geometries.During the KOSI sublimation experiments a dust mantle 1 to 5 millimeter thick formes on top of the samples. This changes the spectrophotometric properties of the sample surfaces in terms of scattering characteristics and water ice absorptions at 1.5 μm. and 2.0 μm. Water ice absorptions observed after the experiment may be partly due to frost contamination.

Spectral radiance factors: Measurement by a gonioradiometric method

An experimental procedure is given for measuring the distribution of light intensity reflected by materials commonly used in interiors. Measurements are carried out in the spectral domain, using a spectrophotometer as detector. They are restricted to the plane of incidence. Preliminary results for grazing incidence show that these materials do not generally behave as uniform diffusers. This conclusion could be important in lighting simulations where the Lambert law is always used extensively. The specular component tends to desaturate the colour of the sample.

歯の分光放射輝度率による色彩学的研究 上顎前歯部について

This research used the spectroradiometer (Pritchard Model 1980 B) to measure the spectral radiance factors of women's maxillary anterior teeth. The following conclusions were reached: 1. The spectral distributions of the anterior teeth were all similar at the cervical, middle, and incisal areas respectively. Their spectral distributions ran in parallel at an almost equal distance, with the curves for the central incisor at the top, below which were those for the lateral incisor and the canine, respectively. 2. The spectral distribution of each area of the central incisor, lateral incisor, and the canine showed their respective distribution curves. The trends of these curves were almost the same for all areas of each tooth. 3. The spectral distribution of each measured portion for women resembled the corresponding portion for men. However, with the central incisor, the spectral distribution curves for women were in a higher position than those for men. With the lateral incisor and the canine, the spectral distribution curves for men were in a higher position than those for women. 4. The spectral distribution of the cervical area showed some absorptional bands, which were identical to those of hemoglobin. 5. Research of the spectral distribution of natural teeth is judged to be helpful in resolving the problem of metamerism.

Committee Report on Specifying Method of Color Rendering Property.

The research committee on color rendering specification (July 1985 — March 1988) of the IEIJ was organized to contribute the work of the CIE for preparing the third edition of the method for specifying the color rendering property of light sources, relating to the revision of the Japanese Industrial Standard (JIS) method. It proposed to CIE TC1-12 (Relative color rendering) statistical average data of actual spectral radiance factors of foliage colors and Japanese women’s complexions as candidates for new test-color samples. For color rendering index calculation, a combination of CIELAB space, Nayatani non-linear model for chromatic adaptation and Watarai’s chroma normalizing equation was proposed. Since TC1-12 dissolved without completing the draft for the third edition, the committee changed its aim for the preparation of a revised JIS method in accordance with the CIE second edition.

Intercomparison on measurement of (total) spectral radiance factor of luminescent specimens

AbstractThis article is based on a CIE Technical Report that describes an intercomparison of measurements of the (total) spectral radiance factor (SRF) of luminescent materials. Seven luminescent specimens were provided as painted panels: two were white containing fluorescent whitening agents and five were chromatic [green, yellow, orange (two), and red]. The SRFs were measured with direct specimen illumination by a source simulating CIE D65. The SRFs that would have been obtained under D65 illumination were calculated by a method selected from among those previously studied by the committee. Data sets from four laboratories (one supplying two sets) gave useful results. The mean CIELAB color difference from the mean of the five data sets was 2.6 units averaged over all data sets and specimens, with a range among specimens from 1.9 to 3.4 units and among data sets from 1.5 to 4.2 units. The mean color difference from the results of an arbitrary reference laboratory was 3.6 units averaged over all data sets and specimens, with a range among specimens from 3.0 to 4.2 units and a range among data sets from 2.1 to 5.3 units. Maximum values of the SRFs varied considerably among the data sets, from 11.4% to 33.6% among the samples. It was the CIE Technical Committee's feeling that these results are representative of the present state of the art for this measurement, despite the relatively poor performance seen.

The influence of spectral bandpass on accuracy of tristimulus data

AbstractWhen calculating tristimulus values from spectral radiance factors which were measured with a spectral bandpass of 10 nm, using data from the same specimen measured with a spectral bandpass of 1 nm and calculated with a 1‐nm interval as standard, and evaluating the significance of the difference in tristimulus values with the CIELAB color difference formula, it is highly probable that a 1‐nm calculation interval will give no greater accuracy than a 10‐nm calculation interval. For this reason it is recommended that the CIE reconsider their approval of the deletion of the 10‐nm calculation interval from the new edition of Publication CIE 15.

Simplified match formulation for fluorescent color specimens

AbstractMatch formulation for fluorescent color specimens is much more difficult than for nonfluorescent color specimens, because both the reflected radiation and the fluorescent radiation must be taken into account. A simple method is described that allows match formulation for fluorescent colors within a small region around an initial color. This method uses a correction matrix and tries to minimize the differences in x, y, and Y and not the differences in the spectral radiance factors. The calculated match formulae are composed of four components, which can be fluorescent or non‐fluorescent enamels. The mode of operation of the method described is demonstrated for green, yellow, and red fluorescent color specimens.

Fluorescence and kubelka‐munk theory

AbstractAn expression is derived for the spectral radiance factor of a thick sample of material which scatters and absorbs light, and to which has been added a fluorescent dye. It is also shown how to work backwards, calculating absorption and emission spectra of the dye from measurements on dyed and undyed samples. This theory has practical application in colorant formulation, and examples using up to three dyes to colour paper are discussed.