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描述了对水的密度进行绝对测量的熔化石英球体体积的确定。此球体的直径用光学干涉仪测量,即将此球体放置在两个平行标准板之间,而其间距的精确值已知。通过测量每块标准板表面到球体之间的间隙而测得其直径。为了使用精确的分数法,采用了两种波长:频率稳定的 He-Ne 激光器为633nm 及 He-Cd 激光器为441nm。详细阐述了为干涉仪克服熔化石英表面的低反射性而采取的特殊安排。同时,也介绍了一种消除由于石英球体的透明性而引起的伪效应的方法。此直径(大约85mm)测得值的标准偏差为5～12nm,体积上就相当于0.16～0.43ppm(1ppm=1×10~(-6)),此体积的总不确定度估计为0.26～0.48ppm。
Describes the determination of the volume of fused silica spheres that make an absolute measurement of the density of water. The diameter of the sphere is measured with an optical interferometer, placing the sphere between two parallel standard plates with known exact spacing. Its diameter is measured by measuring the gap between the surface of each standard plate and the ball. To use the exact fractional method, two wavelengths are used: a He-Ne laser with a frequency stability of 441 nm for 633 nm and a He-Cd laser. The specific arrangements taken to overcome the low reflectivity of the fused quartz surface by the interferometer are described in detail. At the same time, a method to eliminate the false effect caused by the transparency of the quartz sphere is also introduced. The standard deviation of this diameter (about 85 mm) measured from 5 to 12 nm corresponds to a volume of 0.16 to 0.43 ppm (1 ppm = 1 × 10 -6) and the total uncertainty of this volume is estimated to be 0.26 - 0.48ppm.