On the use of conical reflectors in laser displacement interferometry
A laser interferometer with 90/spl deg/ conical reflectors was tested. Reflectors with a conic section of 90/spl deg/ in the meridional plane are of interest in a number of applications, including laser displacement interferometry, especially for measurements in submicrometre range, laser spectroscopy, and multi-pass optical cells.
MEASUREMENT OF THE GRAVITATIONAL CONSTANT USING THE ATTRACTION BETWEEN TWO FREELY FALLING DISCS: A PROPOSAL
The constant of gravitation, G, is the least well-known of the physical constants. A new, independent method of measurement, estimated as having a potential uncertainty at least as small as that achieved by existing methods, would be useful for an improvement in G determination. This experiment is based on the measurement of the relative motion of two freely falling test bodies (discs), caused by their gravitational attraction. The uncertainties are analyzed for two parallel tungsten discs with masses of about 30 kg. The use of test bodies with an incorporated optical system of multipass two-beam interferometers, as well as of multibeam interferometers, is proposed to measure their relative displacement. The estimations were made for laboratory experiment with free fall duration of 0.714 s. In this case, the relative displacement to be measured is about 0.1 μm. These estimates show that relative uncertainties lower than 5 × 10-5 can be obtained in G measurement in a single drop of the test bodies. The pro...
Characteristics of a Fabry–Perot interferometer with two retroreflectors and two beam splitters
An interferometer with two retroreflectors and two beam splitters facing each other can have the characteristics of a Fabry–Perot interferometer. The fringes become sharper as the transmission coefficient of the beam splitter approaches unity. The finesse of the interferometer becomes approximately 150 when the transmission coefficient of the beam splitter is 0.99 and the reflection coefficient of the retroreflector is 1.0. If we apply this interferometer to a gravity gradiometer, the sensitivity of 5.78 × 10−13 s−2 (5.78 × 10−4 E, where E is the unit of gravity gradient) will be possible with the separation of the two retroreflectors of 0.1 m, the laser wavelength of 632 nm, and the laser power of 1 mW