72 results about "Liquid crystal tunable filter" patented technology

A hyper-spectral imaging filter has serial stages along an optical signal path with angularly distributed birefringent retarders and polarizers forming interference filters. The retarders can include tunable birefringent elements such as liquid crystals controlled in unison, fixed retarders and / or combined tunable and fixed birefringences. Distinctly different periodic transmission spectra are provided by different filter stages, each having multiple retarders, in particular with some stages having broad bandpass peaks at wide spectral spacing and other stages have very narrow closely spaced peaks. The respective spectra include at least one tunably selectable band at which the transmission spectra of the filter stages coincide, whereby the salutary narrow bandpass and wide spectral spacing ranges of different stages apply together, resulting in a high finesse wavelength filter suitable for spectral imaging.

A near-infrared spectrum imaging system for diagnosis of the depth and the area of burn skin necrosis comprises a spectrum imager and a computer controlled system. The spectrum imaging system comprises a light source (101), an optical lens (102), a filter (103), a driving controller (105a, 105b, 104), and a CCD camera (106). The filter (103) uses a wide-spectrum liquid crystal tunable filter (LCTF) or an acousto-optic tunable filter (AOTF) that obtain 1100-2500 nm waveband spectral signals of burn skin necrosis tissue of a target region. A compute controlled system is internally provided with a universal module, a data module, a spectrum correction module, a spectrum matching module, and a burn wound three-dimensional synthesizing module. The spectrum imager obtains spectral image data of burn skin necrosis tissue of a target region and inputs the data into the computer controlled system, and the computer controlled system performs image analysis and processing of the data; the depth and the area of burn of the target region can be obtained by means of spectral matching and recognition on a spectral reflectance curve corresponding to each image pixel in an spectral image and a standard spectral reflectance curve in a burn skin necrosis spectral database in a data module, and the data is synthesized into a three-dimensional image for display.

A hyper-spectral imaging filter has serial stages along an optical signal path with angularly distributed birefringent retarders and polarizers forming interference filters. The retarders can include tunable birefringent elements such as liquid crystals controlled in unison, fixed retarders and / or combined tunable and fixed birefringences. Distinctly different periodic transmission spectra are provided by different filter stages, each having multiple retarders, in particular with some stages having broad bandpass peaks at wide spectral spacing and other stages have very narrow closely spaced peaks. The respective spectra include at least one tunably selectable band at which the transmission spectra of the filter stages coincide, whereby the salutary narrow bandpass and wide spectral spacing ranges of different stages apply together, resulting in a high finesse wavelength filter suitable for spectral imaging.

A SWIR hyperspectral imaging filter has serial stages along an optical signal path with angularly distributed birefringent retarders and polarizers. The retarders can include active retarders such as tunable liquid crystal birefringent elements, passive retarders such as fixed retarders, and / or combinations thereof. Distinctly different periodic transmission spectra are provided by different filter stages, each having multiple retarders, in particular with some stages having broad bandpass peaks at wide spectral spacing and other stages have very narrow closely spaced peaks. The respective spectra include at least one tunably selectable band at which the transmission spectra of the filter stages coincide, whereby the salutary narrow bandpass and wide spectral spacing ranges of different stages apply together, resulting in a high finesse wavelength filter suitable for spectral imaging. The filter may be configured to provide faster switching speed and increased angle of acceptance and may operate in the rage of approximately 850-1700 nm.

A detector (110) for determining a position of at least one object is proposed. The detector (110) comprises: at least one angle dependent optical element (130) adapted to generate at least one lightbeam (131) having at least one beam profile depending on an angle of incidence of an incident light beam (116) propagating from the object (112) towards the detector (110) and illuminating the angle dependent optical element (130), wherein the angle dependent optical element (130) comprises at least one optical element selected from the group consisting of: at least one optical fiber, in particular at least one multifurcated optical fiber, in particular at least one bifurcated optical fiber; at least one diffractive optical element; at least one angle dependent reflective element, at least onediffractive grating element, in particular a blaze grating element; at least one aperture stop; at least one prism; at least one lens; at least one lens array, in particular at least one microlens array; at least one optical filter; at least one polarization filter; at least one bandpass filter; at least one liquid crystal filter, in particular a liquid crystal tunable filter; at least one short-pass filter; at least one long-pass filter; at least one notch filter; at least one interference filter; at least one transmission grating; at least one nonlinear optical element, in particular one birfringent optical element; at least two optical sensors (113), wherein each optical sensor (113) has at least one light sensitive area (121), wherein each optical sensor (113) is designed to generateat least one sensor signal in response to an illumination of its respective light-sensitive area by the light beam (131) generated by the angle dependent optical element (130); at least one evaluationdevice (133) being configured for determining at least one longitudinal coordinate z of the object (112) by evaluating a combined signal Q from the sensor signals.

A SWIR hyperspectral imaging filter has serial stages along an optical signal path with angularly distributed birefringent retarders and polarizers. The retarders can include active retarders such as tunable liquid crystal birefringent elements, passive retarders such as fixed retarders, and / or combinations thereof. Distinctly different periodic transmission spectra are provided by different filter stages, each having multiple retarders, in particular with some stages having broad bandpass peaks at wide spectral spacing and other stages have very narrow closely spaced peaks. The respective spectra include at least one tunably selectable band at which the transmission spectra of the filter stages coincide, whereby the salutary narrow bandpass and wide spectral spacing ranges of different stages apply together, resulting in a high finesse wavelength filter suitable for spectral imaging. The filter may be configured to provide faster switching speed and increased angle of acceptance and may operate in the rage of approximately 850-1700 nm.

A VIS-NIR hyperspectral imaging filter has serial stages along an optical signal path with angularly distributed birefringent retarders and polarizers. The retarders can include active retarders such as tunable liquid crystal birefringent elements, passive retarders such as fixed retarders, and / or combinations thereof. Distinctly different periodic transmission spectra are provided by different filter stages, each having multiple retarders, in particular with some stages having broad bandpass peaks at wide spectral spacing and other stages have very narrow closely spaced peaks. The respective spectra include at least one tunably selectable band at which the transmission spectra of the filter stages coincide, whereby the salutary narrow bandpass and wide spectral spacing ranges of different stages apply together, resulting in a high finesse wavelength filter suitable for spectral imaging. The filter may be configured to provide faster switching speed and increased angle of acceptance and may operate in the rage of approximately 400-1100 nm.

The invention is a system and method for obtaining interference and optical coherence tomography images from an object. The system comprises a wideband source, an optical mask for extending the depth of field, a a liquid crystal tunable filter and a phase modulator all of which are uniquely integrated in a Linnik interferometer microscope. The system has several imaging modes: in the time domain mode the device may operate either with wideband illumination or with quasi monochromatic illumination. The monochromatic illumination can be varied in wavelength along a wide spectral region thus allowing true spectroscopic imaging in high resolution and with high speed. Due to the liquid crystal tunable filter and the optical mask, the frequency domain mode is also accessible. The method of obtaining the optical coherence tomography images, both in the time and in the frequency domains, using the liquid crystal retarder is described in detail.

An external-cavity tunable laser with a flexible wavelength grid tuning function comprises a resonant cavity, collimating lenses, an optical isolator, and an output optical fiber. The resonant cavity comprises a semiconductor gain chip, a beam expander collimating lens, a combined liquid crystal tunable filter assembly, and a reflecting mirror. A current injected to the semiconductor gain chip is converted to broadband spontaneously radiating photons through electrical-to-optical conversion, and the photons are spread along a waveguide toward two sides. A part of photons with special frequencies go back and forth multiple times in the resonant cavity to form a laser after a threshold condition is met. The laser is collimated by the collimating lens, passes through the optical isolator, is coupled by the collimating lens, and enters the output optical fiber.