Air refractometer
AssigneeKazumasa Kusaka, Director General of National Institute of Advanced Industrial Science and
InventorsJun Ishikawa, Morimasa Ueda, Hiroki Masuda, Yutaka Kuriyama
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Abstract
An optical measuring light path formed by a vacuum-side laser beam (Pa) as a reference standard and an optical measuring light path formed by a gas-side laser beam (Pb) as a dimension to be measured are coaxially located sandwiching a movable end (optical transparent body 12) of a vacuum container (11) in order to satisfy Abbe's principle requiring linear disposition of the reference standard and the dimension to be measured in measurement direction, thereby reducing measurement error in measuring air refractive index and improving measurement accuracy therefor.
Claims8
An air refractometer, comprising:
- a vacuum container, the length of the vacuum container being variable in longitudinal direction;
- a vacuum-side laser beam advancing inside the vacuum container in the longitudinal direction;
- a vacuum-side laser interferometer using the vacuum-side laser beam;
- a gas-side laser beam parallel to the vacuum-side laser beam and advancing inside a space of a test gas;
- a gas-side laser interferometer using the gas-side laser beam;
- a drive mechanism for driving a movable end of the vacuum container along the longitudinal direction;
- a vacuum-side reflector provided to a vacuum-side of the movable end of the vacuum container for reflecting the vacuum-side laser beam;
- and
- a gas-side reflector provided on a test gas side of the movable end for reflecting the gas-side laser beam,
- a movement of the vacuum-side reflector being measured by the vacuum-side laser interferometer, a movement of the gas-side reflector being measured by the gas-side laser interferometer, the refractive index of the test gas being measured based on the measured values,
- wherein the vacuum-side laser beam and the gas-side laser beam are split from a single laser beam and are respectively introduced to the vacuum-side laser interferometer and the gas-side laser interferometer through a single-mode light-waveguides, the respective laser beams irradiated from the respective single-mode light-waveguides being optical measuring light paths between the respective laser interferometers and the respective reflectors, and
- wherein the optical measuring light path formed by the vacuum-side laser beam and the optical measuring light path formed by the gas-side laser beam are coaxially located sandwiching the movable end of the vacuum container.
Dependencies are inferred from the claim text.