Yasuo Nakagawa

Calibration of 254-nm irradiance based on the silicon photodiode self-calibration technique

A method of calibrating the germicidal irradiance (254 nm) based on the silicon photodiode self-calibration technique has been developed. The absolute responsivity of silicon photodiodes at 254 nm was determined by the self-calibration technique at 633 nm combined with the relative spectral responsivity measurement in the 220-780-nm region based on a standard thermal detector. By using pure 254-nm radiation, the responsivity at 254 nm was transferred to a working standard detector with a sensitivity of onlyt ~254 nm. The irradiance values measured by this detector are compared with those measured with conventional methods; for one method we used an absolutely calibrated thermal detector; for another method we used a monochromator with a spectral irradiance standard. They agreed to within a 3% difference.

Electrically controllable optical attenuator with high deposition rate IrOxitx film

Abstract An electrically controllable optical attenuator was constructed with a solid type electrochromic (EC) device consisting of an “iridium oxide (IrO x )/ion conductive polymer film (PSSA)/WO 3 ” structure. A sputtered iridium oxide film (SIROF) was successfully applied as the EC material to get a uniform absorption change in a wide range of wavelengths (350–1500 nm). It was also shown that a low temperature deposition technique makes it possible to achieve a high depostion rate for the SIROF as well as improved transparency in the bleached state.

Characteristics of the Relatively Large Aparture Thermopile on Chopping Operation

Very low frequency chopping operation of thermopile, which has relatively large aparture and time constant, has been studied and compared with dc mode. Amplification of very low frequency (0.1•`0.3 Hz) is carried out with a digital lock-in system and a usual dc amplifier. Under chopping operation, apparent sensitivity falls with frequency increasing, but noise are also reduced, so detectivity at 0.2 Hz is 107 W-1cm Hz-1/2, which is 1.2 times greater than dc mode. Drift free operation is realised with dc drift component cut off. Linearity and uniformity of receiving area are similar to dc mode. Temperature coefficient of sensitivity has been improved and obtained value is -0.15%/•Ž at 19-29•Ž (about one half of that in dc mode).

Relative Spectral Distribution of Tungsten Coil Lamps

Our studies have been made on the relative spectral distribution over a visible region of coiled fi lament tungsten lamps compared with M-shaped coiled filament lamps. In three laboratories, precise measurement was made with a significant variety of lamp types. All data obtained were reduced into specific curves against the graybody distribution.General standard lamps for luminous intensity and also tungsten-halogen lamps having a single coil and coiled coil filament showed almost unique distribution. This was noted to be the same as that of the M-shaped lamp. A small discrepancy was observed in the shortest wavelength region between the samples and M-shaped lamp. The lower values in the M-shaped lamp were found to have been resulted from the larger absorption of its glass bulb. The type “JC” small projection lamp was the only exception in this case. It has a rather rough and scattered distribution similar to that of the ribbon filament lamp.This paper also presents the numerical analysis and further discussion on the overall emissivity of the coiled filament.