A method for measuring the surface topography of an object including the following steps: a) providing source radiation and dividing the source radiation into illumination radiation and reference radiation, b) illuminating the surface of the object with illumination radiation in a planar illumination field, the surface of the object being illuminated simultaneously with more than one spatial radiation mode and the radiation modes of the illumination being spatially and temporally coherent, but with a fixed phase difference from one another, and c) overlaying the reference radiation on illumination radiation back-scattered at the surface of the object, and detecting an interference signal of the overlaid radiation with a detector. Steps a) to c) are carried out for at least two different, fixed wavelengths. The surface topography of the object is determined by means of digital holography.

A quick subpixel absolute positioning device and method are introduced. The method includes the steps of (A) capturing a real-time speckle pattern of a target surface; (B) providing a coarse-precision speckle coordinate pattern and a plurality of fine-precision speckle coordinate patterns, wherein the coarse-precision speckle coordinate pattern and the fine-precision speckle coordinate patterns include a coordinate value; (C) comparing the real-time speckle coordinate pattern with the coarse-precision speckle coordinate pattern by an algorithm and then comparing the real-time speckle coordinate pattern with the fine-precision speckle coordinate patterns to obtain a coordinate value, wherein each said coarse-precision speckle coordinate pattern corresponds to a set of fine-precision speckle coordinate patterns, and the fine-precision speckle coordinate patterns are obtained when the coarse-precision speckle coordinate pattern is captured again and then captured repeatedly according to a fixed fine-precision displacement distance. Accordingly, the subpixel positioning is attained by quick comparison and manifests high precision.

Disclosed are systems and methods to extract information about the size and shape of an object by observing variations of the radiation pattern caused by illuminating the object with coherent radiation sources and changing the wavelengths of the source. Sensing and image-reconstruction systems and methods are described for recovering the image of an object utilizing projected and transparent reference points and radiation sources such as tunable lasers. Sensing and image-reconstruction systems and methods are also described for rapid sensing of such radiation patterns. A computational system and method is also described for sensing and reconstructing the image from its autocorrelation. This computational approach uses the fact that the autocorrelation is the weighted sum of shifted copies of an image, where the shifts are obtained by sequentially placing each individual scattering cell of the object at the origin of the autocorrelation space.

The present invention relates to the technical field of full-field laser vibration measurement systems, and specifically relates to a full-field Z-direction displacement measurement system. Dynamic measurement is achieved on the basis of the traditional laser shearing speckle interferometry by using a spatial domain phase shift method. The homogeneity and similar measurement accuracy of the laser shearing speckle interferometry and the Doppler interferometry are further used to help the laser shearing speckle interferometry to implement absolute displacement measurement by using the single-point time domain Doppler interferometry. By means of the improvements in these aspects, the measurement system of the present invention can achieve full-field Z-direction displacement measurement, high-precision full-field absolute value vibration measurement and transient depth measurement, can have important applications in depth measurement, three-dimensional sensing, vibration measurement in aerospace and the depth measurement in new material characterization detection and other fields, and has very important applications in fields involving vibration optimization of complex structures such as the automotive development industry, the mechanical industry, the equipment manufacturing industry in China, etc.

The invention describes a device (1) for characterizing the rough profile of a tissue sample comprising: a laser source (2) that illuminates the surface (100) of the tissue; a photodetector (3) that receives the light backscattered by the surface (100) of the tissue; and further a displacement means (4) configured to alternate between a first position wherein a rotating ground glass (5) is disposed within the path of the laser beam towards the surface (100), a second position wherein a rotating half wave blade (6) is disposed within the path of the laser beam towards the surface (100); and a third position wherein within the path of the laser beam towards the surface (100) neither the ground glass plate (5) nor the half wave blade (6) are arranged, or the half wave blade (6) is arranged in a fixed non-rotating position.

Disclosed are systems and methods to extract information about the size and shape of an object by observing variations of the radiation pattern caused by illuminating the object with coherent radiation sources and changing the wavelengths of the source. Sensing and image-reconstruction systems and methods are described for recovering the image of an object utilizing projected and transparent reference points and radiation sources such as tunable lasers. Sensing and image-reconstruction systems and methods are also described for rapid sensing of such radiation patterns. A computational system and method is also described for sensing and reconstructing the image from its autocorrelation. This computational approach uses the fact that the autocorrelation is the weighted sum of shifted copies of an image, where the shifts are obtained by sequentially placing each individual scattering cell of the object at the origin of the autocorrelation space.

Image processing device (50) of the present invention comprises: an enhancement processing means (51) that enhances a speckle pattern in an ocular fundus tomographic image; a region-of-interest setting means (52) that sets a desired region in the ocular fundus tomographic image with the enhanced speckle pattern as a region-of-interest; a feature value extracting means (53) that extracts a feature value of the speckle pattern in the region-of-interest; and a disease determining means (54) that makes disease determination for an ocular fundus on the basis of the feature value. Image processing method of the present invention comprises: a step (S3) of enhancing a speckle pattern in an ocular fundus tomographic image; a step (S4) of setting a desired region in the ocular fundus tomographic image with the enhanced speckle pattern as a region-of-interest; a step (S5) of extracting a feature value of the speckle pattern in the region-of-interest; and a step (S6) of making disease determination for an ocular fundus on the basis of the feature value.

Speckle contrast optical tomography system provided with at least one point source and multiple detectors, means for providing different source positions, the point source having a coherence length of at least the source position-detector distance and means for arranging the source position-detector pairs over a sample to be inspected, the system being further provided with means for measuring the speckle contrast; the speckle contrast system of the invention thus capable of obtaining 3D images.

A downhole tool system includes a bottom hole assembly that includes a connector; a laser head; a light source; a sensing assembly; and a controller. The connector is configured to couple to a downhole conveyance run into a wellbore to a reservoir rock formation. The laser head is configured to emit a laser beam toward the reservoir rock formation at a fixed frequency. The light source emitter is configured to emit a light beam toward the reservoir rock formation. The sensing assembly includes at least one optical receiver configured to (1) receive a reflected laser beam and a reflected light beam, and (2) interfere the reflected laser beam with the reflected light beam. The controller is configured to perform operations including generating a speckle interferogram based on the interference; and determining an angular displacement and an axial displacement of the wellbore based on the speckle interferogram.

A downhole tool system includes a bottom hole assembly that includes a connector; a laser head; a light source; a sensing assembly; and a controller. The connector is configured to couple to a downhole conveyance run into a wellbore to a reservoir rock formation. The laser head is configured to emit a laser beam toward the reservoir rock formation at a fixed frequency. The light source emitter is configured to emit a light beam toward the reservoir rock formation. The sensing assembly includes at least one optical receiver configured to (1) receive a reflected laser beam and a reflected light beam, and (2) interfere the reflected laser beam with the reflected light beam. The controller is configured to perform operations including generating a speckle interferogram based on the interference; and determining an angular displacement and an axial displacement of the wellbore based on the speckle interferogram.