<title>Realizing subnanometer accuracy level in gauge block measurements</title>

Abstract

A new fringe-pattern analyzing interferometer, featuring ultimate resolution of a few parts in iOu, stability of readings of about 0. 1 nm and non-excluded systematic uncertainties due to optic effects of less than 1 nm, has been used to study some systematic effects in gauge block length measurements. Measurements on steel and quartz plates are analyzed. Limitations of the present definition of the length of the block are outlined. Stability and reproducibility of the wringing procedure for steel and quartz plates are reported. A new double-ended method in length measurements of gauge blocks has been realized.It includes determination of the corrections for non-ideal optics of the interferometer, curvature of the plate and deformations of the quartz plate due to wringing of the block to its surface. The result of the length measurement is not affected, in the first approximation, by deformation ofthe plate and the quality of wringing.

Scientific basis for traceable dimensional measurements in a nanometer range: methods and concepts

“…The resolution of our comparator was measured earlier using a double frequency HP-laser with 2 MHz frequency difference between the orthogonally polarized modes. It was found to be about 0.5 A° (0.05 nm) [7]. The time stability with some averaging procedure over different fringe patterns was also below 1 A°, or 0.…”

“…It is worthy of note here, that for one measurement of the optical phase change value, eight different interferometric measurements are necessary in the general case. So, the indicated uncertainty level in measurements has been obtained as a result of the very high resolution of the comparator [7], and of the high temporal stability of the temperature and pressure measuring systems. The idea of the establishing experimental relation between the measurements of the mechanical and the optical lengths of a block is very fruitful, and results in a "calibrated" double-sided method [2].…”

“…Wringing number p AGP An important improvement in the accuracy of the length measurements has been achieved after discovery of the possibility of highly reproducible wringing and the development of the new parallax-free methods in optical length measurements [1][2][3][4]. All ofthem are based on the reproducible wringing technique [5][6][7]. Its idea is very simple.…”

<title>Interferometric length and roughness measurements with nanometer accuracy level</title>

“…In some papers [3,5], for selected blocks with smaller deviations in flatness, the variability of the wringing film thickness is reported to be about nm (at 95% confidence level). In this paper, we describe a new approach in the interferometric length measurements that is based on the technique of the reproducible wringing [6][7][8][9]. It gives the opportunity to measure the physical length of the material artifact without the excessive wringing film thickness and results in the accuracy of the phase change measurements at the optical reflection from surface of the material standard of better than I nm.…”

The design of a double ended interferometer (DEI)

“…Other investigations, in particular, by Titov in various papers [8,9], explore the measurements of gauge blocks to sub nm and suggested ways to overcome this phase change deviation. One of the suggestions was wringing with a slave block technique.…”