The principal component analysis was applied to the spectral power distributions of actual fluorescent lamps, and three characteristic functions S_F1 (λ), S_F2 (λ) and S_F3 (λ) were derived. Based on the average spectral power distribution J (λ) and these three characteristic functions, reconstituted spectral power distributions of fluorescent lamps J_Ft (λ) were derived with arbitrary chromaticity coordinates and with arbitrary general color-rendering index by the following equation.
J_Ft (λ) =J(λ) +k₁S_F1 (λ) +k₂S_H2 (λ) +k₃S_F3 (λ)
By use of these spectral power distributions, the following subjects were discussed;
(1) The maximum value of the general color-rendering index was Rα =93.4 for reconstituted fluorescent lamps with the same chromaticity coordnates as those of the CIE standard illuminant C.
(2) The value of σ², variance of deviations in spectral power distributions between the test and the reference illuminant, had its minimum corresponding to the maximum value of the general colorrendering index.
(3) Deviations of chromaticity coordinates of eight test object colors for the general color-rendering index were clarified between the CIE illuminant C and each of reconstituted fluorescent lamps with different values of Rα.
(4) On twelve gray object colors which were metameric with respect to the CIE standard illuminant C and the CIE 1931 standard observer, failures of preserving color match among them were discussed under each of the above reconstituted fluorescent lamps. Average color differences ΔE_M, the measure of the failure of preserving color matching among metameric object colors, have the following simple relations with Rα for the actual fluorescent lamps.
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An infrared radiation thermometer for measuring surface temperature of targets in a normal temperature region has been developed.
The construction, operating mechanism and specification of this instrument and some data obtaind by it are described in this paper.
Two types of measuring head based on different optical systems have been designed and constructed. One is a reflection type using Cassegrain mirrors, and the other a refraction type.
The refraction type contains a germanium objective lens (40mm in focal length, f/1.4) coated on both surfaces with thin films of ZnS (nt=2.5μ), and two kinds of optical band pass filters limited the sensitive region of the instrument in wavelength between 8 and 12μ.
A thermister bolometer as the infrared detector is installed in its compartment which is held at a definite temperature around 30°C by the temperature controlling system and serves as the reference radiant source for the detector.
The measuring radiation temperature range extenss from-70°C to +90°C, especially normal temperature region (10°C-45°C) is most sensitive. Minimum detectable temperature difference is within 0.2deg. at 30°C.
Temperature measurement of a target is affected by its emmisivity and the temperature of the objective lens. Some considerations for probable errors caused by them and the practical correction methods have been discussed.

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