Method for speckle mitigation in an interferometric distance meter by determining a pointing direction
AssigneeLeica Geosystems AG
InventorsMarcel Rohner, Yves Salvade
Life of this patent
Estimating the term…
Abstract
A method for speckle mitigation in an interferometric distance meter comprises the steps of transmitting optical radiation with at least one wavelength λ to a target to be surveyed, receiving a portion of the optical radiation scattered back by the target in an optical axis (OA), wherein the optical radiation forms a speckle field, converting the received optical radiation into at least one received signal, determining a true distance to the target from the received signal by absolute or incremental interferometric distance measurements. In the method the true pointing direction relative to the optical axis (OA) is determined, wherein the distance error due to speckle effects is corrected.
Claims16
A method for speckle mitigation in an interferometric distance meter comprising the steps:
- transmitting optical radiation with at least one wavelength λ to a target to be surveyed;
- receiving a portion of the optical radiation scattered back by the target in an optical axis, wherein the optical radiation forms a speckle field;
- converting the received optical radiation into at least one received signal;
- determining a true distance to the target from the received signal by absolute or incremental interferometric distance measurements with compensation of phase decorrelation errors;
- and
- determining a pointing direction of the interferometric measurement to at least one point of the speckle field, relative to the optical axis, wherein the speckle field is at least partially resolved.
An interferometric distance meter comprising:
- a radiation source for transmitting optical radiation with at least one wavelength X to a target to be surveyed;
- a receiver for receiving a portion of the optical radiation scattered back by the target in an optical axis and for converting the received optical radiation into at least one received signal, wherein the receiver is adapted for at least partially resolving a speckle field with a number of K detectors or a scanning device for moving at least one detector relative to the speckle field;
- an interferometer setup;
- and
- a signal processing unit with a distance estimator for determining a true distance to the target from the received signal with compensation of phase decorrelation errors, and a pointing direction estimator for determining pointing directions relative to the optical axis and for at least partially resolving the speckle field.
Dependencies are inferred from the claim text.