Abstract: A gradient of gravity is defined by a change in the optical path length required to maintain equality in optical path lengths of two beam arms which direct light beams to impinge upon and reflect from two freefalling test masses.

Abstract: A gravity value is measured using two light beams which each reflect from both a freefall test mass and a stationary reference test mass which is inertially supported by a long period isolation device. The optical path lengths of the light beams change equally and oppositely in response to gravity and equally in response to disturbances, resulting in cancellation of the undesirable effects of the disturbances by common mode rejection and in a desirable increase in the number of gravity induced measurement fringes, when the two light beams are combined interferometrically.

Abstract: Incident differently-polarized light beams are separately directed and combined by one or two corner cube structures, each having one or two walls formed as a beam splitter. One incident light beam is passed, while the other incident light beam is reflected.

Abstract: A gravity gradient is measured interferometrically from two polarized light beams having mutually different polarization planes which reflect from opposite surfaces of two freefalling test masses. The two polarized light beams project along matched coincident beam paths and divert from the coincident paths to interact with the freefalling test masses. An enhanced level of common mode rejection of adverse influences arises from traversing the coincident beam paths.

Abstract: A gradient of gravity is defined by a change in the optical path length required to maintain equality in optical path lengths of two beam arms which direct light beams to impinge upon and reflect from two freefalling test masses.

Abstract: A gravity gradient is measured interferometrically from two light beams which each reflect from both of two freefalling test masses. The light beams project in beam arms which remain equal in length as the two test masses freefall except for different effects of gravity on each test mass and any initial relative velocity difference imparted to the test masses. The optical path length of the beam arms also change equally and oppositely during freefall, to amplify the interferometric effect by four times. A high level of common mode rejection eliminates many spurious influences.

Abstract: A test mass used for light beam interferometric gravity characteristic measurement has a center of mass located equidistant and colinear with optical center points of two oppositely reflecting retroreflectors. Rotation of the test mass about its center of mass during freefall changes the path length of the oppositely reflected light beams by equal amounts, thereby achieving common mode cancellation of the effects of test mass rotation when the two reflected light beams are interferometrically combined.

Abstract: A gravity value is measured using two light beams which each reflect from both a freefall test mass and a stationary reference test mass which is inertially supported by a long period isolation device. The optical path lengths of the light beams change equally and oppositely in response to gravity and equally in response to disturbances, resulting in cancellation of the undesirable effects of the disturbances by common mode rejection and in a desirable increase in the number of gravity induced measurement fringes, when the two light beams are combined interferometrically.

Abstract: A gravity gradient is measured interferometrically from two polarized light beams having mutually different polarization planes which reflect from opposite surfaces of two freefalling test masses. The two polarized light beams project along matched coincident beam paths and divert from the coincident paths to interact with the freefalling test masses. An enhanced level of common mode rejection of adverse influences arises from traversing the coincident beam paths.

Abstract: Incident differently-polarized light beams are separately directed and combined by one or two corner cube structures, each having one or two walls formed as a beam splitter. One incident light beam is passed, while the other incident light beam is reflected.

Abstract: A gravity gradient is measured interferometrically from two light beams which each reflect from both of two freefalling test masses. The light beams project in beam arms which remain equal in length as the two test masses freefall except for different effects of gravity on each test mass and any initial relative velocity difference imparted to the test masses. The optical path length of the beam arms also change equally and oppositely during freefall, to amplify the interferometric effect by four times. A high level of common mode rejection eliminates many spurious influences.

Abstract: A test mass used for light beam interferometric gravity characteristic measurement has a center of mass located equidistant and colinear with optical center points of two oppositely reflecting retroreflectors. Rotation of the test mass about its center of mass during freefall changes the path length of the oppositely reflected light beams by equal amounts, thereby achieving common mode cancellation of the effects of test mass rotation when the two reflected light beams are interferometrically combined.

Abstract: A differential gradient of gravity is directly measured from the interferometric combination of two light beams which reflect from pairs of three freefalling test masses. Optical path lengths of two beam arms change relative to one another because of differential gradient of gravity effects the test masses differently simultaneous freefall. The relatively large background of gravity and the gradient of gravity are eliminated from the measurement while simultaneously achieving a high level of common mode rejection of other spurious influences.

Abstract: The present invention provides devices and methods for reducing or eliminating sources of systematic errors in the measurement of absolute gravity or gravity field gradients; specifically, an improved test mass for an interferometer is disclosed that reduces the influence of nearby electromagnetic fields on a freefalling test mass.