1957 年 4 巻 2 号 p. 40-42
In our privious reports, to measure a distance of 5m, by interference of light waves, we multiplied lengths by ten times in each step . For a distance shorter than lm., how ever, we have already found the possibility of applying twenty times multiplication at a time. In this report, we examine the applicability of the multiplication of more than ten times to a distance of 5m, and succeed to compare a 5m, etalon directly with a 25cm, etalon and even with a 20cm, one respectivery, using normal incident ray and spectroscopic method. These cases correspond to 20 and 25 times multiplications respectively . Although details are not given as to the latter comparison, a check experiment is described performed as to the former comparison. The direct comparison of 5m . and 25 cm, etalons is compared with the indirect one in which a 50cm, etalon is used as an intermediate distance. The result shows the discrepancy of 7×10-8 for the total length between these two comparisons. This inconsistency, however, may be considered inevitable in view of the instability of the atmospheric conditions in the measuring room and of the high and different temperature coefficients of respective etalons. It is confirmed that a distance of 5m, is measurable through only one step of multiplication from the distance of 20cm, which is measurable directly by the light from a Hg-198 lamp.