32results about How to "Suppress backscatter" patented technology

The invention discloses a photon fence system for monitoring on security protection of perimeter at night. The system comprises: a pulsing laser, which is used for emitting a laser pulse to carry out illumination on an object; a gated imaging device, which is used for controlling exposure time by a pulse width of a gated pulse; a time schedule controller, which is used for controlling time delay between the gated pulse and the laser pulse; and a computer, which is used for carry out controlling, image processing and displaying on the pulsing laser, the gated imaging device and the time schedule controller. According to the system provided in the invention, a pulsing laser is utilized as a light source and a gated imaging device is employed as a detector; time delay between a gated pulse and a laser pulse is controlled so as to establish a photon fence in space, wherein the photon fence is invisible for human eyes; therefore, when an invading object passed through the photon fence, image information of the invading object is collected and background outside the photon fence and a non-invading object are removed by filtering, so that non-background extraction on the invading object is realized.

The invention discloses a novel topological photonic crystal structure and an optical waveguide, and a unit cell of the novel topological photonic crystal structure is formed by arranging six identical dielectric cylinders into two independent regular triangle units and has C3 rotational symmetry. A plurality of structural states of the crystal structure all have a dual Dirac cone cell, and energyband inversion and topological phase transition are achieved by stretching and compressing at least one of the two triangular units on the basis of each cell state having a dual Dirac cone, and a large topological non-mediocre photonic band gap is opened. An optical waveguide is also constructed based on the crystal structure, the topological non-mediocre photonic crystal (PC3) and the topological mediocre photonic crystal (PC1) are combined to support optical unidirectional transmission at the interface to inhibit backscattering, the transmission efficiency is extremely high, the immunity tostructural defects is strong, and three different structural defects can be perfectly passed.

The purpose of the present invention is to provide a fluorescent-light-source device in which, when a wavelength conversion member is exposed to excitation light, backscattering of said excitation light is minimized and fluorescent light generated inside the wavelength conversion member is utilized effectively and emitted to the outside with high efficiency, yielding a high light-emission efficiency. This fluorescent-light-source device is characterized by the provision of a wavelength conversion member in the form of a florescent material that is excited by excitation light. This fluorescent-light-source device is further characterized in that: a periodic structure comprising substantially cone-shaped protrusions arrayed in a periodic fashion is formed on an excitation-light-receiving surface on the wavelength conversion member; the aspect ratio of said periodic structure, namely the quotient of the heights of the protrusions and the period of the periodic structure, is at least 0.2; and said period falls within a range within which fluorescent light emitted by the florescent material is diffracted.

A process for producing a light-diffusing element is provided by which a light-diffusing element having a high haze and high diffusing properties and reduced in backward scattering can be produced at low cost with high productivity. The process for producing a light-diffusing element comprises a step in which a matrix-forming material comprising a resin-ingredient precursor and an ultrafine-particle ingredient is brought into contact with fine light-diffusing particles, a step in which at least some of the precursor is infiltrated into an inner part of the fine light-diffusing particles, and a step in which the precursor that has infiltrated into the inner part of the fine light-diffusing particles and the precursor that has not infiltrated into the fine light-diffusing particles are simultaneously polymerized to form a matrix comprising the resin ingredient and the ultrafine-particle ingredient and simultaneously form a concentration gradation region in the vicinity of the inner side of the surface of the fine light-diffusing particles.

The invention relates to an optical nano antenna, in particular to a silicon nanosphere trimer-based unidirectional optical nano antenna structure. The antenna structure is formed by three nanospheresin an X=Y axis symmetric form; the diameters D of the three nanospheres are 200-280 nm; the distances between the nanospheres located on the two sides of the symmetric axis and the nanosphere locatedat the center of the symmetric axis are 0; and the material of the nanospheres is a high dielectric material silicon. The structure can be used for adjusting the far-field direction characteristics;the wave vectors of incident waves are parallel to the x axis direction; and the polarization is parallel to the y axis direction. By utilizing a multistage decomposition method for analysis, the structure not only supports electric dipole and magnetic dipole resonance, but also supports electric quadrupole and annular dipole resonance; and through the coupling of the resonance modes, the far-field unidirectional scattering of the high dielectric material silicon nanosphere trimer structure is realized. Solid theoretical foundation is provided for realizing far-field unidirectional controllable nano antennas.

There is provided an extremely thin light diffusing film, which has strong light diffusibility, has suppressed backscattering, and is excellent in productivity. The light diffusing film includes: a first region having a first refractive index; a substantially spherical shell-shaped refractive index modulation region surrounding the first region; and a second region having a second refractive index, the region being positioned on a side of the refractive index modulation region opposite to the first region. The light diffusing film has a light diffusion half-value angle of 30° or more and a thickness of 4 μm to 25 μm, and satisfies the following expressions (1) and (2):

y≦0.011x (30≦x≦60)  (1)

y≦0.0275x−0.99 (60<x)  (2)

where x represents the light diffusion half-value angle (°) and y represents a backscattering ratio (%), the expressions (1) and (2) each representing a relationship between a numerical value for the light diffusion half-value angle and a numerical value for the backscattering ratio.

The invention discloses a short coherent illumination and polarization combined underwater long-distance optical imaging device and method. The system comprises a short coherent laser, an optical imaging system, a polarizer and an analyzer, wherein a polarizer is arranged at the image side end of the short coherent laser, the analyzer is arranged at the object side end of the optical imaging system, a laser emitted by the short coherent laser enters an imaging target through the polarizer, the imaging target is arranged in a water body environment, and a reflected light beam of the imaging target is transmitted to the optical imaging system through the analyzer.

The invention discloses a double-ring parallel resonant gyro system and a double-closed-loop digital demodulation method thereof. The system comprises a tunable laser, outgoing light of the tunable laser is split into clockwise light and anticlockwise light through a signal beam splitter, the clockwise light and the anticlockwise light sequentially enter an acousto-optic frequency shifter, an electro-optic modulator, an optical fiber coupler, a hollow photonic band gap optical fiber resonant cavity, a photoelectric detector and a digital lock-in amplifier respectively, and frequency closed-loop feedback is formed through the tunable laser and the acousto-optic frequency shifter respectively. According to the double-ring hollow photonic band gap optical fiber structure, clockwise and anticlockwise light waves are respectively propagated in the independent resonant cavities without mutual influence, so that the temperature stability is improved, and nonreciprocal effect noises such as anoptical Kerr effect, Rayleigh backscattering and the like are effectively inhibited. According to the double-closed-loop digital demodulation method, optical frequencies in a clockwise optical path and an anticlockwise optical path are locked at respective transmission resonant frequencies, so that the system works in a linear region, and the linear range of angular velocity detection of the system and the linearity of a scale factor are effectively improved.

The invention discloses a wake flow detection device based on time-dependent single photon counting and an operation method of the wake flow detection device, and belongs to the field of laser underwater wake flow target detection. The device includes a laser emitting assembly, a laser receiving assembly and an information processing assembly, wherein the laser emitting assembly and the laser receiving assembly are both electrically connected with the information processing assembly, and the laser emitting assembly is used for irradiating bubbles in wake flow with laser and synchronously transmitting an initial electric signal to the information processing assembly; the laser receiving assembly is used for receiving reflected light reflected by the bubbles in the wake flow and synchronously transmitting a termination electric signal to the information processing assembly; and the information processing assembly is used for receiving the initial electric signal transmitted by the laser transmitting assembly and the termination electric signal transmitted by the laser receiving assembly, completing photon flight time interval measurement and time-dependent single photon counter analysis, and finally calculating to obtain a target distance. According to the invention, detection of underwater weak wake flow echo signals can be realized, and the technical limitation of low sensitivity in the prior art is overcome.

An object of the present invention is to provide a light diffusing element having a high haze value, strong diffusibility, a smooth surface, and suppressed backscattering. The light diffusing element of the present invention includes: a matrix including a resin component and ultrafine particle components; and light diffusing fine particles dispersed in the matrix, in which part of the resin component permeates the light diffusing fine particles, and a permeation range of the resin component in the light diffusing fine particles is 90% or more with respect to an average particle diameter of the light diffusing fine particles in the light diffusing element, and in which the light diffusing element has an arithmetic average surface roughness Ra of 0.04 μm or less.

The invention relates to a single-photon three-dimensional imaging system and an imaging method thereof. The imaging system comprises a transceiving common-aperture light path, a laser emission unit,a single-photon detection unit, a scanning galvanometer unit and a data processing system, the transceiving common-aperture light path comprises a perforated reflector, and laser emitted by the laseremitting unit enters the transceiving common-aperture light path through a through hole of the perforated reflector; an echo light signal is reflected by the reflecting surface of the perforated reflector and then enters the single-photon detection unit; the scanning galvanometer unit is arranged on a transceiving common-aperture light path and controls and adjusts the laser transmitting directionand the echo light signal receiving direction; and the data processing system performs three-dimensional image reconstruction according to the data of the emergent laser and the echo light signal. Alaser transceiving common-aperture scheme is adopted, the structure is compact, and the reliability is high.