Pneumatic CellのFlexible Mirrorの感度に対する影響
1959 年 28 巻 7 号 p. 415-419
詳細
1959 年 28 巻 7 号 p. 415-419
The flexible mirror of a pneumatic cell is the important part that affects the sensitivity of the cell. The mirror involves two main factors: the tension and the reflectivity. The performance of the cell becomes the better, the weaker the tension and the higher the reflectivity, but the weakening of the tension by reducing the mass of evaporated metal would result in the lowering of reflectivity of the mirror which in turn lowers the gain of the optical system. The detecting sensitivity is thus represented by the product of the said two factors, each of which is governed by the thickness of the evaporated metal film, suggesting that there are optimum conditions assigned to the mirror as enumerated below.
1) The most favourable thickness of the collodion base film is 50mμ_??_100mμ for the tension of about 3100 dynes/cm.
2) The tension of the mirror for practical use is of the order of 104 dynes/cm which corresponds to the restoring power of about 105 dynes/cm.
3) The ambient temperature affects the tension, weakening it by about 200 dynes/cm per degree rise of the temperature between 5°C and 15°C.
4) The reflectivity of the mirror increases rapidly with the thickness of evaporated antimony film until about 20mμ, approaching thereafter gradually to 65% as the film thickenss.
5) The optimum thickness of antimony film on the flexible mirror is about 20mμ provided that the transmitted rays do not disturb the gas temperature.
