49 results about "Near field scattering" patented technology

This invention involves measurement of optical properties of materials with sub-micron spatial resolution through infrared scattering scanning near field optical microscopy (s-SNOM). Specifically, the current invention provides substantial improvements over the prior art by achieving high signal to noise, high measurement speed and high accuracy of optical amplitude and phase. Additionally, it some embodiments, it eliminates the need for an in situ reference to calculate wavelength dependent spectra of optical phase, or absorption spectra. These goals are achieved via improved asymmetric interferometry where the near-field scattered light is interfered with a reference beam in an interferometer. The invention achieves dramatic improvements in background rejection by arranging a reference beam that is much more intense than the background scattered radiation. Combined with frequency selective demodulation techniques, the near-field scattered light can be efficiently and accurately discriminated from background scattered light. These goals are achieved via a range of improvements including a large dynamic range detector, careful control of relative beam intensities, and high bandwidth demodulation techniques. In other embodiments, phase and amplitude stability are improved with a novel s-SNOM configuration.

This invention involves measurement of optical properties of materials with sub-micron spatial resolution through infrared scattering scanning near field optical microscopy (s-SNOM). Specifically, the current invention provides substantial improvements over the prior art by achieving high signal to noise, high measurement speed and high accuracy of optical amplitude and phase. Additionally, it some embodiments, it eliminates the need for an in situ reference to calculate wavelength dependent spectra of optical phase, or absorption spectra. These goals are achieved via improved asymmetric interferometry where the near-field scattered light is interfered with a reference beam in an interferometer. The invention achieves dramatic improvements in background rejection by arranging a reference beam that is much more intense than the background scattered radiation. Combined with frequency selective demodulation techniques, the near-field scattered light can be efficiently and accurately discriminated from background scattered light. These goals are achieved via a range of improvements including a large dynamic range detector, careful control of relative beam intensities, and high bandwidth demodulation techniques. In other embodiments, phase and amplitude stability are improved with a novel s-SNOM configuration. In other embodiments an absorption spectrum may be obtained directly by comparing properties from a known and unknown region of a sample as a function of illumination center wavelength.

The invention provides a flat top effect estimation method for a near-field radar scattering cross section of a rectangular flat plate. A critical state is reached when the included angle between a connecting line from a radiation source to one end point of the rectangular flat plate and the rectangular flat plate is 90 degrees, and the included angle between the connecting line from the radiation source to the end point of the rectangular flat plate and an R is a critical incident angle Theta, wherein the critical incident angle Theta is equal to arcsin (D / 2R), D is the length of the flat plate and R is the vertical distance from the radiation source to the flat plate, and the width M of the flat top is quantificationally estimated to be twice the corresponding critical incident angle Theta according to a geometric relationship. The invention provides a simple method for estimating the width of the flat top of the near-field RCS (Radar Cross Section), the width of flat top of the near-field RCS is quantificatioinally estimated from the point of the geometric relationship, the blind spot of the field is solved, and the obtained conclusion is more accurate. Moreover, by virtue of the method, a favorable ground is provided for analyzing the near-field scattering flat top phenomenon of the flat plate and a building thereof, and the method is good for the prediction and the analysis on the near-field RCS of various targets with a similar flat plate structure.

The invention discloses a flow two-dimensional velocity field measurement method and device based on near-field scattering, wherein the measurement device includes a laser, a spatial filter, a collimator lens, a lens group, a CCD camera and a computer, and Compared with the prior art, the present invention has the following advantages: the measuring device is quite simple, does not require high centering of the optical path, and can realize effective removal of stray light without adding a complex device for removing central light intensity; The particle size of the tracer particles required by the measurement technology can be smaller than the wavelength of the incident light emitted by the laser, and the concentration of the tracer particles can also be relatively high, which can be applied to the measurement of the two-dimensional velocity field of nanofluid flow; the data analysis of this measurement technology It is simple and fast, can realize online measurement, and adopts the differential processing method to ensure that the accuracy and linearity of the speed measurement method are not limited by the particle size and concentration of the tracer particles.