223results about How to "Speckle reduction" patented technology

In accordance with the invention, a low coherence interferometer is used to non-invasively monitor the concentration of glucose in blood by shining a light over a surface area of human or animal tissue, continuously scanning the light over a two dimensional area of the surface, collecting the reflected light from within the tissue and constructively interfering this reflected light with light reflected along a reference path to scan the tissue in depth. Since the reflection spectrum is sensitive to glucose concentration at particular wavelengths, measurement and analysis of the reflected light provides a measure of the level of glucose in the blood. The measurement of glucose is taken from multiple depths within blood-profused tissue, and sensitivity is preferably enhanced by the use of multiple wavelengths. Noise or speckle associated with this technique is minimized by continuously scanning the illuminated tissue in area and depth.

A laser imaging system with reduced speckle is disclosed. The laser imaging system includes spatially superpositioned 1-D arrays or alternatively 2-D arrays of independent emitters of laser radiation, with each emitter having a spectral bandwidth Δλi centered at some arbitrary wavelength λ0i. The elements of the array are allowed, by design, to have a slightly different central wavelength, thereby creating an ensemble bandwidth ΔΛ which is much greater than the bandwidth Δλi of any individual emitter in the array. The resulting increased bandwidth reduces speckle in a displayed image.

The invention relates to techniques for speckle reduction in holographic optical systems, in particular holographic image display systems. We describe a holographic image display system for displaying an image holographically on a display surface, the system including: a spatial light modulator (SLM) to display a hologram; a light source to illuminate said displayed hologram; projection optics to project light from said illuminated displayed hologram onto said display surface to form a holographically generated two-dimensional image, said projection optics being configured to form, at an intermediate image surface, an intermediate two-dimensional image corresponding to said holographically generated image; a diffuser located at said intermediate image surface; and an actuator mechanically coupled to said diffuser to, in operation, move said diffuser to randomise phases over pixels of said intermediate image to reduce speckle in an image displayed by the system.

A method and apparatus for reducing speckle uses polarization averaging. A polarizing beam splitter divides a first polarized laser output into a second polarized laser output and a third polarized laser output. A plurality of mirrors creates an optical path difference between the second and third polarized laser outputs. The optical path difference is at least about a coherence length for the first polarized laser output. The second and third polarized laser outputs are combined into a fourth laser output, which illuminates a depolarizing screen. If a human eye or an optical system having a intensity detector views the depolarizing screen, the eye or the intensity detector will detect reduced speckle, which results from uncorrelated speckle patterns created by the second polarized laser output and the third polarized laser output. A first alternative embodiment of the invention functions without the optical path difference being at least about the coherence length. In the first alternative embodiment, a piezoelectric transducer varies an optical path length by at least about a half wavelength of the first polarized laser output. By varying the optical path length by a sufficient frequency, the eye or the intensity detector will detect the reduced speckle. A second alternative embodiment combines two orthogonally polarized laser outputs, from two lasers, into a combined laser output. The combined laser output illuminates the depolarizing screen. A third alternative embodiment rotates the first laser output with a rotation frequency to form a rotating polarized laser output, which illuminates the depolarizing screen.

A display system for providing a user viewable visible image, includes a view screen for receiving organic laser light and having a diffusing optical element so that the view screen, in response to organic laser light, produces a viewable visible image, wherein the diffusing optical element includes a viewing angle greater than 160° in a first viewing direction and greater than 100° in a second viewing direction orthogonal to the first direction; one or more organic laser light sources arranged in an array with each such laser light source including a vertical cavity design and means for projecting and modulating the intensity of the organic laser light from the array onto the view screen in a pattern to cause a visual image to be produced by the view screen; and means associated with the view screen for reducing speckle in the organic laser light.

A method and system for reducing speckle in an image produced from a coherent source of radiation is provided. The method includes coupling a source beam received from a coherent optical source into an optical fiber. A position of at least a portion of the fiber may be modulated using a ditherer. The source beam may be refracted by a lens after it is decoupled from the optical fiber, such that the source beam is aimed at a microlens diffuser. In accordance with a particular embodiment, the source beam may be projected from the microlens diffuser onto a spatial modulator. The spatial modulator may be positioned to project the source beam via an imaging lens, to a target.

A method and apparatus for reducing speckle due to MSL, without any loss of resolution, by averaging over different angles of the incident light at low input resolution, while collecting the backscattered light at a full resolution of a lens is described. The present invention allows discrimination against the speckle due to coherent MSL.

A method and apparatus that reduces laser speckle by using stimulated Raman scattering in an optical fiber. The pulse repetition frequency of the laser is adjusted to control aspects of the laser light such as color or despeckling. In DLP projection systems, an optical monitor may be used to send information to a bit sequence, and the bit sequence may control the pulse repetition frequency of the laser based on the optical monitor signal.

A laser projector having a configurable spatial light modulator (SLM) adapted to display various spatial modulation patterns and redirect illumination from a laser to form an image on the viewing screen. The laser projector drives the SLM to change spatial modulation patterns at a rate that causes the corresponding sequence of projected images to fuse to mitigate appearance of speckle in the resulting fused image. The SLM can be designed to redirect the illumination using either diffraction or specular reflection of light from the displayed spatial modulation pattern. In one embodiment, the SLM is a MEMS device having an array of individually addressable mirrors supported over a substrate and adapted to move (e.g., translate and / or rotate) with respect to the substrate.

Disclosed herein are systems and related methods for reducing speckle on display screen. More specifically, screen vibration is used to reduce speckle, and in accordance with the disclosed principles, the vibration may be achieved by using wave-based actuation (e.g., acoustic or electromagnetic waves) to vibrate the screen. In an exemplary embodiment, a speckle reducing system may comprise at least one actuating element located proximate to, but not in physical contact with, a display screen. In addition, the at least one actuating element may be configured to generate waves directed towards the display screen. When the waves impact the display screen, the waves impart vibration to the display screen.

The present invention relates to non-contact optical scanning of an object for generation of a three-dimensional surface model of the scanned object. In particular the invention relates to a scanner for obtaining the three-dimensional geometry of at least a part of the surface of an object, said scanner comprising: —at least one light source, preferably a laser light source with adjustable power, —projection means for directing light from the at least one light source to a moving spot on the surface of the object, —at least one image sensor adapted to record at least one image of at least a part of the surface, —detection means, other than the at least one image sensor, for monitoring at least a part of the light reflected from the surface, —regulation means for adjusting the intensity of the at least one light source based on the amount of light reflected from the surface, and—means for transforming the at least one image to a three-dimensional model of the surface.

Speckle, a factor reducing image quality in optical coherence tomography (“OCT”), can limit the ability to identify cellular structures that are important for the diagnosis of a variety of diseases. Exemplary embodiments of the present invention can facilitate an implementation of an angular compounding, angular compounding by path length encoding (“ACPE”) for reducing speckle in OCT images. By averaging images obtained at different incident angles, with each image encoded by path length, ACPE maintains high-speed image acquisition and implements minimal modifications to OCT probe optics. ACPE images obtained from tissue phantoms and human skin in vivo demonstrate a qualitative improvement over traditional OCT and an increased signal-to-noise ratio (“SNR”). Accordingly, exemplary embodiments of an apparatus probe catheter and method can be provided for irradiating a sample. In particular, an interferometer may forward forwarding an electromagnetic radiation. In addition, a sample arm may receive the electromagnetic radiation, and can include an arrangement which facilitates a production of at least two radiations from the electromagnetic radiation so as to irradiate the sample. Such exemplary arrangement can be configured to delay a first radiation of the at least two radiations with respect to a second radiation of the at least two radiations.

The invention discloses a double-color laser light source which comprises a blue laser and a red laser which emit blue laser light and red laser light respectively; and a fluorescent wheel, the surface of which is coated with green fluorescent powders, wherein the green fluorescent powders emit green fluorescence when excited by the blue laser light. The double-color laser light source also comprises a speckle dissipation system. The speckle dissipation system comprises a first diffusion portion which is controlled to rotate, is arranged in a beam shaping optical path of the blue laser light and red laser light and is used for diffusing the blue laser light and the red laser light; and a second diffusion portion which is controlled to rotate, is arranged before a blue laser light, red laser light and green fluorescence incident light bar, and is used for at least penetrating the blue laser light and the red laser light sequentially and forming blue light and red light output. The double-color laser light source can effectively reduce speckle effect and improve display quality of projected images.

An ultrasound diagnosis apparatus of the present invention has: an image generator configured to execute transmission / reception of ultrasound waves to chronologically generate ultrasound image data of plural frames; a multiresolution decomposition part configured to hierarchically perform multiresolution decomposition on the ultrasound image data to acquire first-order to nth-order (n represents a natural number of 2 or more) low-band decomposition image data and first-order to nth-order high-band decomposition image data; a feature amount calculator configured to calculate a feature amount based on the acquired low-band decomposition image data; a filtering processor configured to perform a filtering operation on the calculated feature amount; and a multiresolution composition part configured to execute multiresolution composition using the low-band decomposition image data and high-band decomposition image data to generate a composite image. Thus, the apparatus can efficiently reduce change in speckle / noise in the temporal direction and perform a process without a time phase delay.

The invention relates to a laser-based light source comprising a laser device (1) adapted for generating laser light of a predetermined laser wavelength and emitting this laser light as a laser beam; a light-conversion device (2) for converting at least part of the laser light into converted light; a laser-output sensor (7) for determining a laser-output signal proportional to the output of laser light emitted by the laser device (1); a converted-light sensor (6) for determining a converted-light signal proportional to the output of converted light emitted by the light-conversion device (7); and a controller (9) which is adapted for receiving the laser-output signal and the converted-light signal, for determining a safe-to-operate parameter, based on the laser-output signal and the converted-light signal, and for controlling the operation of the laser-based light source, based on a comparison of the safe-to-operate parameter with a at least one predefined threshold. In this way, a laser-based light source is proposed which enables reliable eye-safety in an easy way.

A method and system for reducing speckle in an image produced from a coherent source of radiation is provided. The method includes coupling a source beam received from a coherent optical source into an optical fiber. A position of at least a portion of the fiber may be modulated using a ditherer. The source beam may be refracted by a lens after it is decoupled from the optical fiber, such that the source beam is aimed at a microlens diffuser. In accordance with a particular embodiment, the source beam may be projected from the microlens diffuser onto a spatial modulator. The spatial modulator may be positioned to project the source beam via an imaging lens, to a target.

X-ray mammography has been the standard for breast cancer screening for three decades, but offers poor statistical reliability; it also requires a radiologist for interpretation, employs ionizing radiation, and is expensive. The combination of multiple independent tests, performed effectively at the same time and co-registered, can produce substantially more reliable detection performance than that of the individual tests. The multi-sensor approach offers greatly improved reliability for detection of early breast tumors, with few false positives, and also can be designed to support machine decision, thus enabling screening by general practitioners and clinicians; it avoids ionizing radiation, and can ultimately be relatively inexpensive.

An external cavity laser may be swept rapidly in frequency and cavity length to prevent formation of modes providing improved spectral response and light characteristics.

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.

We describe a holographic image projector, comprising: a laser light source to provide light at a laser wavelength; a first spatial light modulator (SLM) to display a hologram, wherein said first SLM is illuminated by said laser light source; intermediate image optics to provide a first intermediate real image plane at which a real image produced by said hologram displayed on said first SLM is formed; a wavelength-conversion material located at said first intermediate real image plane to convert said laser wavelength to at least a first output wavelength different to said laser wavelength; and second optics to project light from said real image at said output wavelength to provide a displayed image.

For displaying a color image by recombination of several single color images, parasitic noise like speckles due to scattering within the system, in particular when laser light is involved, with the invention a significant improvement with a low number of parts can be realized by use of a color wheel that comprises in radially divided zones refractive elements for redirecting light beams incoming at different impinging angles and redistributing elements, e.g. a hologram, that provide for a defined output beam in an optical axis. The sequence of the individual light processing zones on the color wheel are synchronized with respective laser sources. The invention combines the functionality of plural elements, reduces speckles and avoids losses.

A laser projector having a configurable spatial light modulator (SLM) adapted to display various spatial modulation patterns and redirect illumination from a laser to form an image on the viewing screen. The laser projector drives the SLM to change spatial modulation patterns at a rate that causes the corresponding sequence of projected images to fuse to mitigate appearance of speckle in the resulting fused image. The SLM can be designed to redirect the illumination using either diffraction or specular reflection of light from the displayed spatial modulation pattern. In one embodiment, the SLM is a MEMS device having an array of individually addressable mirrors supported over a substrate and adapted to move (e.g., translate and / or rotate) with respect to the substrate.

Methods and devices for producing cavitation in tissue are provided. In one embodiment, a low-frequency ultrasound pulse is transmitted into tissue, a high-frequency ultrasound pulse is transmitted into tissue, and a composite waveform is formed in the tissue that has a peak negative pressure value that exceeds an intrinsic threshold for cavitation in the tissue. In some embodiments, the peak negative pressures of the individual ultrasound pulses do not exceed the intrinsic threshold for cavitation. In another embodiment, a plurality of ultrasound pulses at various resonant frequencies are transmitted into tissue, and the time delays between these transmissions are adjusted to allow the ultrasound pulses to align temporally and form a monopolar pulse having a compound peak negative pressure that exceeds an intrinsic threshold for cavitation in the tissue. Systems for performing Histotripsy therapy are also discussed.

A method for detecting the positioning of an entity, comprising the steps of (a) using a projector, which comprises a laser and a MEMS micro mirror arranged to receive light from the laser and which can oscillate about at least one oscillation axis, to project light towards the entity to project an image which is composed of pixels onto the entity, wherein the image has a first density of pixels; (b) changing the density of pixels in the projected image; (c) sensing at least a portion of light of the projected image which is reflected from the entity; and (d) using the sensed portion of light to determine the position of the entity. There is also provided a corresponding device for detecting position. There is also provided a method and device for determining distance which involves using the sensed portion of light to determine the distance between the entity and projector.

A projection display surface for reducing speckle artifacts from a projector having at least one narrow band light source having an incident visible wavelength band, wherein the incident visible wavelength band has an incident peak wavelength and an incident bandwidth, comprising: a substrate having a reflective layer that reflects incident light over at least the incident visible wavelength band; and a fluorescent agent distributed over the reflective layer, wherein the fluorescent agent absorbs a fraction of the light in the incident visible wavelength band and emits light in an emissive visible wavelength band having an emissive peak wavelength and an emissive bandwidth; wherein return light from the projection display surface produced when incident light in the incident visible wavelength band is incident on the projection display surface contains light in both the incident visible wavelength band and emissive visible wavelength band, thereby reducing speckle artifacts.

An illumination apparatus forms, onto a linear array light modulator, a line of illumination that extends in a linear direction. The illumination apparatus has a first laser array with laser emitters for forming a first linear beam array and a second laser array with laser emitters for forming a second linear beam array. An array combiner aligns at least the first and second linear beam arrays in the linear direction and directs the first and second linear beam arrays along a propagation path to form a mixed illumination. At least first and second cylindrical lens elements having power in the linear direction relay the mixed illumination from the propagation path toward the linear array light modulator. At least third and fourth cylindrical lens elements having power in the cross-array direction that is orthogonal to the linear direction focus the mixed illumination onto the linear array light modulator.

A system and a method for creating a stable and reproducible interface of an optical sensor system for measuring blood glucose levels in biological tissue include a dual wedge prism sensor attached to a disposable optic that comprises a focusing lens and an optical window. The disposable optic adheres to the skin to allow a patient to take multiple readings or scans at the same location. The disposable optic includes a Petzval surface placed flush against the skin to maintain the focal point of the optical beam on the surface of the skin. Additionally, the integrity of the sensor signal is maximized by varying the rotation rates of the dual wedge prisms over time in relation to the depth scan rate of the sensor. Optimally, a medium may be injected between the disposable and the skin to match the respective refractive indices and optimize the signal collection of the sensor.

An optical signal generator is configured with an associated control system and driver configured to reduce speckle. Speckle reduction occurs by pulsing the drive signal between a first current level and a second current level. These pulses force the optical signal generator to introduce oscillations into the optical signal. The coherence of the emitted light is reduced during the period of oscillations in the optical signal, which reduces speckle. In one embodiment, the pulsing of the drive signal brings the drive signal down to a level near or below threshold, which in turn intermittently turns off the optical signal output. Returning the optical signal to a desired optical output intensity introduces the speckle reducing oscillation. The pulse frequency, and duty cycle is controlled by a duty cycle control signal to modulate overall optical power and adjust amount of despeckle.