Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Absolute gas refractometer without gas-filling and pumping process
  benefiting from quasi-synthetic wavelength theory   We present a method to measure the refractive index of gas at 633 nm
absolutely, which does not need filling or pumping gas during the measurement.
We develop a quasi-synthetic wavelength (QSW) theory by means of the
configuration of two-frequency Jamin interferometry and vacuum tubes with
specific lengths. With the aid of the QSW theory, we construct a gas
refractometer and demonstrate its performance by the measurement of dry air and
nitrogen gas at different pressures ranging from 80 kPa to 100 kPa. The results
indicate that the refractometer has an uncertainty of better than 1E-7 and a
dynamic range of 3.95E-4.

11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci