130 results about "Speckle contrast" patented technology

A projection video display includes at least one laser for delivering a light beam. The display includes a beam homogenizer and a condenser lens. A scanning arrangement is provided for scanning the light in beam in a particular pattern over the condenser lens in a manner that effectively increases the beam divergence. The scanned beam is homogenized by a beam homogenizer and a spatial light modulator is arranged to receive the homogenized scanned light beam and spatially modulate the beam in accordance with a component of an image to be displayed. Projection optics are projecting the homogenized scanned light beam onto a screen. The scanning provides that the homogenized scanned light beam at the screen has a coherence radius less than the original coherence radius of the beam. The reduced coherence radius contributes to minimizing speckle contrast in the image displayed on the screen. The screen includes one or more features providing a further contribution to minimizing speckle contrast in the displayed image. In one example, the screen includes a transparent cell containing a liquid having light scattering particles in suspension.

Methods and apparatus for measuring perfusion using transmission laser speckle imaging are provided. The apparatus comprises a coherent light source and a detector configured to measure transmitted light associated with an unfocused image at one or more locations. The coherent light source and detector are positioned in a transmission geometry. The apparatus further comprises means for securing the coherent light source and the detector to the tissue sample in a fixed transmission geometry relative to the tissue sample. The apparatus may further comprise at least one processor to receive information from the detector and process detected variations in transmitted light intensity to determine a single metric of perfusion. The method may comprise the steps transilluminating a tissue sample with coherent light, recording spatial and / or temporal variations in the transmitted light signal, determining speckle contrast value(s), and computing a metric of perfusion.

A projection video display includes at least one laser for delivering a light beam. The display includes a beam homogenizer and a condenser lens. A scanning arrangement is provided for scanning the light in beam in a particular pattern over the condenser lens in a manner that effectively increases the beam divergence. The scanned beam is homogenized by a beam homogenizer and a spatial light modulator is arranged to receive the homogenized scanned light beam and spatially modulate the beam in accordance with a component of an image to be displayed. Projection optics are projecting the homogenized scanned light beam onto a screen. The scanning provides that the homogenized scanned light beam at the screen has a coherence radius less than the original coherence radius of the beam. The reduced coherence radius contributes to minimizing speckle contrast in the image displayed on the screen. The screen includes one or more features providing a further contribution to minimizing speckle contrast in the displayed image. In one example, the screen includes a transparent cell containing a liquid having light scattering particles in suspension.

An optical system (100) comprises a coherent light source (101) and optical elements for directing light from the source to a target (1001). The optical elements include at least one diffusing element (141, 161) arranged to reduce a coherence volume of light from the source and a variable optical property element (151). A control system (1021) controls the variable optical property element such that different speckle patterns are formed over time at the target (1001) with a temporal frequency greater than a temporal resolution of an illumination sensor or an eye (1011) of an observer so that speckle contrast ratio in the observed illumination is reduced. The variable optical property element (151) may be a deformable mirror with a vibrating thin plate or film.

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.

Provided are a laser speckle contrast imaging method, a laser speckle contrast imaging system, and an apparatus which includes the laser speckle contrast imaging system. The laser speckle contrast imaging system includes a laser light source configured to irradiate laser beams toward a subject, the laser beams having a plurality of wavelength bands and different surface transmittances with respect to the subject. An imaging unit is configured to acquire speckle images by capturing images of speckles by using an image sensor, the speckles being formed when the irradiated laser beams are scattered from the subject. A signal processor is configured to convert the acquired speckle images into speckle contrast images and to acquire a compensated speckle contrast image by compensating for a change caused by a movement of the subject.

A system and method for reducing peak power of a laser pulse and reducing speckle contrast of a single pulse comprises a plurality of elements oriented to split and delay a pulse or pulses transmitted from a light emitting device. The design provides the ability to divide the pulse into multiple pulses by delaying the components relative to one another. Reduction of speckle contrast entails using the same or similar components to the power reduction design, reoriented to orient received energy wherein angles between the optical paths are altered such that the split or divided light energy components strike the target at different angles or different positions. An alternate embodiment for reducing speckle contrast is disclosed wherein a single pulse is passed in an angular orientation through a grating to create a delayed portion of the pulse relative to the leading edge of the pulse.

A selectable high dynamic laser speckle blood flow imaging device and method include a laser source, a sample fixing table, a beam expander, a half-mirror, a first CCD camera, a second CCD camera anda stepping motor. Continuous acquisition of original speckle images using multi-exposure acquisition is carried out, which solves the shortcoming of the traditional laser speckle contrast imaging method that the original speckle image is captured by a fixed exposure time. In addition, the present invention provides a dual imaging system. The whole body blood flow image is obtained by the focusingsystem, the local area is enlarged by the zoom system to obtain the angiographic image with more blood vessel information, and the images obtained by the two optical systems are fused to obtain the angiographic image with higher imaging resolution. It will be of great significance in the fields of early diagnosis of diseases, disease analysis and dynamic monitoring of drug efficacy in vivo.

A method of operating a laser source comprising is provided. The method reduces speckle contrast in a projected image by creating a plurality of statistically independent speckle patterns. The method comprises generating a plurality of sub-beams that define an optical mode. The method further comprises controlling the phase of selected sub-beams to continuously sequence the laser source through a plurality of orthogonal optical modes. The plurality of orthogonal modes create a corresponding number of statistically independent speckle patterns, thus reducing speckle contrast in a image projected using the laser source by time averaging.

Apparatus for generating optical radiation includes a laser, which is configured to operate in multiple transverse modes simultaneously so as to generate an input beam, which is characterized by a first speckle contrast. The transverse modes of the input beam are optically mixed so as to generate an output beam have a second speckle contrast, which is substantially less than the first speckle contrast.

A non-invasive method for measuring blood flow in principal vessels of a heart of a subject is provided. The method includes illuminating a region of interest in the heart with a coherent light source, wherein the coherent light source has a wavelength of from about 600 nm to about 1100 nm; sequentially acquiring at least two speckle images of the region of interest in the heart during a fixed time period, wherein sequentially acquiring the at least two speckle images comprises acquiring the at least two speckle images in synchronization with motion of the heart of the subject; and electronically processing the at least two acquired speckle images based on the temporal variation of the pixel intensities in the at least two acquired speckle images to generate a laser speckle contrast imaging (LSCI) image and determine spatial distribution of blood flow rate in the principal vessels and quantify perfusion distribution in tissue in the region of interest in the heart from the LSCI image.

Blood flow rates can be calculated using diffuse speckle contrast analysis in spatial and time domains. In the spatial domain analysis, a multi-pixel image sensor can be used to detect a spatial distribution of speckles in a sample caused by diffusion of light from a coherent light source that is blurred due to the movement of scatterers within the sample (e.g., red blood cells moving within a tissue sample). Statistical analysis of the spatial distribution can be used to calculate blood flow. In the time domain analysis, a slow counter can be used to obtain time-series fluctuations in light intensity in a sample caused by diffusion of light in the sample that is smoothened due to the movement of scatterers. Statistical analysis of the time-series data can be used to calculate blood flow.

The invention discloses a speckle-free three primary color laser light source. The light source includes an infrared laser module, a green laser module, a blue laser module, a power transmitting fiber; a collimating lens, one diffuser which is spun by a motor; one converging lens which is intended for converging multiple beams of laser rays; and one rectangular optical integrator which is intended for outputting even rectangular speckles. The invention also discloses a laser projection system. According to the invention, the method for eliminating laser speckles emphasizes on conducting speckle elimination on green laser that is sensitive to human eyes, and has visible effects. The speckle-free laser light source, by adopting three primary colors special optical fiber coupling and clustering power synthesis technology, realizes high-brightness small optical expansion and even laser output. The laser projection system adopts the speckle-free laser light source of the invention, can effectively reduce the laser speckle contrast ratio of a projection picture, and increases the quality of the projected display image.

A projector includes a light source module, a diffuser for diffusing the light beam emitting from the light source module, and a fluorescent plate. The light source module includes a light source capable of emitting a first light beam, a dichroic device for diverging the first light beam into a second light beam and a third light beam, and a reflector with a moving frequency exceeding 20 Hz configured for reflecting the third light beam. The fluorescent plate is configured for converting the light beam passing through the diffuser into at least three kinds colored light beams.

The invention relates to a laguerre-gaussian beam-based speckle contrast imaging measurement device and a laguerre-gaussian beam-based speckle contrast imaging measurement method. The device comprises a continuous wave laser; after being reflected by a total reflective mirror, a light beam emitted by the continuous wave laser irradiates on a collimating beam expander; after that, the light beam becomes linearly polarized light by a polarizer and then irradiates on a beam splitting prism; after passing through the beam splitting prism, the light beam is divided into two beams, wherein one path is reflected light, and the other path is transmission light; the reflected light beam irradiates on a spatial light modulator, and the light beam reflected by the spatial light modulator irradiates on a diaphragm after passing through the beam splitting prism and an analyzer again; after passing through the diaphragm, the light beam irradiates on a sample to be tested; after being scattered by the sample to be tested, the light beam is converged by an imaging lens, and then an image is formed in a charge coupled device (CCD) camera; after that, the image is stored in a computer, and the image contrast value can be calculated; when a light path is difficult to adjust, the speckle size is adjusted by changing the characteristics of the illumination beam, so that the method has the characteristics of being flexible and reliable; the method is widely applied to the fields such as hemorheology monitoring, plant growth condition monitoring, etc.

Laser scanner projection systems that reduce the appearance of speckle in a scanned laser image are provided. The laser projection system includes a visible light source having at least one laser, a scanning element and a system controller. The system controller is programmed to generate a scanned laser image. The system further includes a first lens that focuses a scanned output beam onto an intermediate image and a second lens that projects the intermediate image onto a projection surface. A periodic phase mask having a period that is approximately equal to or greater than the beam waist diameter of the scanned output beam is positioned at the intermediate laser image. The period of the periodic phase mask is such that the projection of the scanned output beam jumps progressively from pixel to pixel, thereby reducing speckle contrast in the scanned laser image.

The invention discloses a multi-mode imaging system for observing cerebral cortex functions of moving animals, comprising a light source device, an image transferring optical fiber, a light transferring optical fiber, a spectroscope, an intrinsic signal imaging part, a laser speckle contrast imaging part, a fluorescence Imaging part, an animal activity room, an image acquisition card, a computer, wherein the light source device generates three light sources needed by an imaging mode, the image transferring optical fiber is used for transferring the cerebral cortex images to a spectroscope when the animals moves around freely; the light transferring optical fiber transfers the light of the light source to the cerebral cortex of the aminals; the spectroscope divides imaging light beam transferred by the image transferring optical fiber into three beams and carries out intrinsic signal imaging, laser speckle contrast imaging and fluorescence Imaging; the intrinsic signal imaging part is used for the intrinsic signal imaging; the laser speckle contrast imaging part for laser speckle contrast imaging; the fluorescence Imaging part is used for fluorescence Imaging; the animal activity room is used for the experiment animals to move freely; the image acquisition card is used for image acquisition and the computer for system control and image receiving and processing.In the invention, optical fiber light and image transferring can be used to multi-mode imaging when the animals are conscious and active and the invention comprises intrinsic signal imaging, laser speckle contrast imaging and fluorescence Imaging.

An embodiment in accordance with the present invention provides a system and method for imaging living tissue and processing laser speckle data anisotropically to calculate laser speckle contrast preferentially along the direction of blood flow. In the present invention, raw laser speckle images are obtained and processed resulting in the anisotropic laser speckle images. The system and method involve the determination of the direction of blood flow for every pixel within the region of interest (primary pixel) and subsequent extraction of a set of secondary pixels in the spatio-temporal neighborhood of the primary pixel that is anisotropic in the direction of blood flow. Speckle contrast is then calculated for every primary pixel as the ratio of standard deviation and mean of all secondary pixels in this anisotropic neighborhood and collectively plotted using a suitable color mapping scheme to obtain an anisotropic laser speckle contrast image of the region of interest.

The present disclosure describes, among other things, a reduced speckle contrast microelectromechanical system. One exemplary embodiment includes micromechanical structures configured to form a uniform reflective surface on a substrate, an elastic substance coupled to the substrate, and an energy source that applies a voltage to the elastic substance to alter the shape of the surface of the substrate, for example, by about 10% to about 25% of a wavelength of light projected onto the substrate at a frequency of at least 60 Hz. Another exemplary embodiment includes micromechanical structures formed on a surface of a substrate, a reflective diaphragm connected to the substrate, an elastic substance coupled to the diaphragm, and an energy source that applies a voltage to the elastic substance to vibrate the diaphragm at a frequency of at least 60 Hz.

An image projector having one or more broadband lasers designed to reduce the appearance of speckle in the projected image via wavelength diversification. In one embodiment, a broadband laser has an active optical element and a nonlinear optical element, both located inside a laser cavity. The broadband laser generates an output spectrum characterized by a spectral spread of about 10 nm and having a plurality of spectral lines corresponding to different spatial modes of the cavity. Different individual spectral lines effectively produce independent speckle configurations, which become intensity-superimposed in the projected image, thereby causing a corresponding speckle-contrast reduction.

Examination of the structure and function of blood vessels is an important means of monitoring the health of a subject. Such examination can be important for disease diagnoses, monitoring specific physiologies over the short- or long-term, and scientific research. This disclosure describes technology and various embodiments of a system and method for imaging blood vessels and the intra-vessel blood flow, using at least laser speckle contrast imaging, with high speed so as to provide a rapid estimate of vessel-related or blood flow-related parameters.

The invention discloses a phase modulator performance parameter testing device based on beam coherent combination. The phase modulator performance parameter testing device comprises a laser (1), a 1*2 optical beam splitter (2), a first optical fiber, a second optical fiber, a third optical fiber and a fourth optical fiber, a phase modular (4), a first optical collimator, a second optical collimator, a beam combining lens (6), a beam splitter prism (7), a first microobjective, a second microobjective, a digital camera (9), a pinhole (10), a photoelectric detector (11), a frequency response tester (12) and a computer (13). The phase modulator performance parameter testing device simplifies measurement of phase modulator performance parameters and can measure all phase modulators with optical fiber interfaces. Simultaneously, the device can roughly estimate and accurately measure resonant frequency. When accuracy requirements are not high, the digital camera is used for observing far field speckle contrast to obtain the resonant frequency simply and rapidly; and when the accuracy requirements are high, accurate resonant frequency is obtained through analysis and calculation of signals acquired by the photoelectric detector.

The invention discloses a speckle generating device and a speckle generating method with an adjustable contrast value. The speckle generating device comprises a continuous wave laser, wherein a light beam zoom unit, a polarizer, a diaphragm, a spatial light modulator, an analyzer, a Fourier lens and a CCD (Charge Coupled Device) camera are sequentially arranged in the forward direction of a light beam of the continuous wave laser; speckle field information generated by the spatial light modulator is imaged by the CCD camera and then is stored in a computer; the spatial light modulator and the CCD camera are connected with the computer respectively; an image on the spatial light modulator is written by the computer; the light beam zoom unit is used for controlling the beam waist size of a laser beam emitted to the spatial light modulator; the spatial light modulator is positioned on a front focal plane of the Fourier lens; the CCD camera is positioned on a rear focal plane of the Fourier lens. Moreover, the speckle generating device has the advantages of simple principle, simple device, online adjustment and the like and can be widely applied to the fields of laser speckle illumination microscopy technologies, speckle contrast value testing technologies and the like.

The invention discloses a scanning dark field laser speckle blood flow imaging method and device. Biological tissue is illuminated by means of space localized linear or dotted laser beams, scanning is conducted along the surface of the tissue to be tested, and the whole area to be tested is traversed. During each time of scanning, a laser speckle image reflected by the whole area to be tested (containing the area directly illuminated by the laser beams and the surrounding area not directly illuminated) is acquired by an area array CCD or CMOS camera through an optical imaging system, the laser speckle contrast corresponding to each pixel is calculated, and then the laser speckle image is converted into a blood flow image. Pixel weighted averaging is conducted on the blood flow images obtained by scanning the illumination laser beams at different positions, so that the final two-dimensional blood flow distribution image of the biological tissue in the area to be tested is obtained. The method and device have the advantages that the contribution of diffusion photons subjected to multiple scattering in the tissue to imaging is expanded, and detection depth is improved compared with a traditional laser speckle blood flow imaging method adopting broad-beam laser illumination.

A projection device includes a diffuser and a light source system. The light source system includes a light source, a dichroic element, an actuator, and a reflector. The light source generates a light beam that is directed to the dichroic element. The dichroic element forms first and second individual light beams from the light beam. The first individual light beam is transmitted to the diffuser. The second individual light beam is reflected from the reflector to the diffuser. The actuator is fixed to the reflector and has a removal frequency exceeding 20 Hz.

The invention relates to a speckle measuring and evaluating method in laser projection display. A power spectrum density function of a speckle pattern is utilized to evaluate the effect of speckle elimination, and the method comprises the steps that: three one-dimensional physical quantities which are respectively a radial power spectrum density rPSD, an angle power spectrum density aPSD and a total power spectrum density tPSD are defined for the speckle pattern to be measured and evaluated, wherein the three one-dimensional physical quantities respectively reflect speckle granularity, anisotropy and speckle severity in the pattern; and the calculated values of the above three physical quantities are analyzed to provide a speckle measuring and evaluating result. Compared with speckle contrast, the method can analyze the speckle pattern more comprehensive, the speckle severity in the pattern is evaluated, the speckle granularity is measured, and the differences of different speckle elimination methods in speckle elimination in all directions are evaluated. The invention has a great significance on the comparison of different speckle elimination methods and the application of a laser projection display technology.

A speckle contrast reducing method for a laser scanning projection system includes the following steps. Firstly, a laser beam is provided. The laser beam is projected on a projection surface according to a first scanning trajectory, thereby generating a first image frame. Sequentially, the laser beam is projected on the projection surface according to a second scanning trajectory, thereby generating a second image frame at an image refresh rate. Moreover, the second scanning trajectory of the second image frame is shifted by a displacement from the first scanning trajectory of the first image frame along a slow-axis direction.

Non-invasive methods for determining blood flow distribution in a region of interest are provided. The method includes illuminating a region of interest of a subject with a coherent light source; sequentially acquiring at least two speckle images of the region of interest, wherein sequentially acquiring the at least two speckle images comprises acquiring the at least two speckle images in synchronization with motion of the heart of the subject; and electronically processing the at least two acquired speckle images based on the temporal variation of the pixel intensities in the at least two acquired speckle images to generate a laser speckle contrast imaging (LSCI) image, determine distribution of blood flow speed in principal vessels and quantify perfusion distribution in tissue in the region of interest from the LSCI image. The LSCI image enables detection of different blood flow speeds.