840 results about "Photon counting" patented technology

In the systems and methods of the present invention a multifocal multiphoton imaging system has a signal to noise ratio (SNR) that is reduced by over an order of magnitude at imaging depth equal to twice the mean free path scattering length of the specimen. An MMM system based on an area detector such as a multianode photomultiplier tube (MAPMT) that is optimized for high-speed tissue imaging. The specimen is raster-scanned with an array of excitation light beams. The emission photons from the array of excitation foci are collected simultaneously by a MAPMT and the signals from each anode are detected using high sensitivity, low noise single photon counting circuits. An image is formed by the temporal encoding of the integrated signal with a raster scanning pattern. A deconvolution procedure taking account of the spatial distribution and the raster temporal encoding of collected photons can be used to improve decay coefficient. We demonstrate MAPMT-based MMM can provide significantly better contrast than CCD-based existing systems.

This invention is directed to a 3-dimensional imaging lidar, which utilizes modest power kHz rate lasers, array detectors, photon-counting multi-channel timing receivers, and dual wedge optical scanners with transmitter point-ahead correction to provide contiguous high spatial resolution mapping of surface features including ground, water, man-made objects, vegetation and submerged surfaces from an aircraft or a spacecraft.

The invention provides methods and apparatus for detecting radiation including x-ray photon (including gamma ray photon) and particle radiation for radiographic imaging (including conventional CT and radiation therapy portal and CT), nuclear medicine, material composition analysis, container inspection, mine detection, remediation, high energy physics, and astronomy. This invention provides novel face-on, edge-on, edge-on sub-aperture resolution (SAR), and face-on SAR scintillator detectors, designs and systems for enhanced slit and slot scan radiographic imaging suitable for medical, industrial, Homeland Security, and scientific applications. Some of these detector designs are readily extended for use as area detectors, including cross-coupled arrays, gas detectors, and Compton gamma cameras. Energy integration, photon counting, and limited energy resolution readout capabilities are described. Continuous slit and slot designs as well as sub-slit and sub-slot geometries are described, permitting the use of modular detectors.

A light wave rangefinder includes a light transmitting optical system for directing a laser pulse at a target, and a light receiving optical system for receiving reflected light from the target, including a Geiger-mode avalanche photodiode (APD) array and a non-imaging optical device. The non-imaging optical device is positioned between the received reflected light and the APD array, and is configured to uniformly distribute the received reflected light across the APD array. The APD array is uniformly illuminated by a single received reflected laser pulse, producing a plurality of Geiger-mode avalanche events.

An optical rangefinder based on time-of-flight measurement, radiates pulsed light toward an object (70), and receives reflected light from the object, the receiver operating in a photon counting mode, so as to generate a pulse for a detected photon. There is a variable probability of a photon detection on the receiver, and a controller (370, 380, 390; 365, 470, 475, 380, 390; 570, 580, 590, 390) controls the photon detection probability of the receiver, based on a light level. By controlling the detection probability according to a light level, the receiver can have an increased dynamic range, and without the expense of using optical components. This can apply even while detecting very weak signals since the receiver can still be in a photon counting mode while the detection probability is controlled. The light level can be indicated by an output of the receiver itself, or by another detector external to the receiver.

A system for detecting and graphically displaying a contents of a fast-moving target object comprises: a radiation source, having a position such that at least a portion of radiation emitted from the radiation source passes through the fast-moving target object, the fast-moving target object having a variable velocity and acceleration while maintaining a substantially constant distance from the radiation source and being selected from the group consisting of: a vehicle, a cargo container and a railroad car; a velocity measuring device configured to measure the variable velocity of the fast-moving target object; a detector array comprising a plurality of photon detectors, having a position such that at least some of the at least a portion of the radiation passing through the target object is received thereby, the detector array having a variable count time according to the variable velocity and a grid unit size; a counter circuit coupled to the detector array for discretely counting a number of photons entering individual photon detectors, the counter circuit measuring a count rate according to a contents within the fast-moving target object; a high baud-rate interface coupled to the counter circuit for sending count information from the counter circuit at a rate fast enough to support real-time data transfer therethrough; and a processor coupled to the velocity measuring device and to the high-baud-rate interface, receiving count information from the high baud-rate interface and generating distortion-free image data in real time as a function of the count information and the variable velocity. A method for using the system is also disclosed.

A CT detector includes a first detector configured to convert radiographic energy to electrical signals representative of energy sensitive radiographic data and a second detector configured to convert radiographic energy to electrical signals representative of energy sensitive radiographic data and positioned to receive x-rays that pass through the first detector. A logic controller is electrically connected to the first detector and the second detector and is configured to receive a logic output signal from the second detector indicative of an amount of a saturation level of the first detector, compare the logic output signal to a threshold value, and output, based on the comparison, electrical signals from the first detector, the second detector, or a combination thereof to an image chain.

A technique is provided for forming a multi-layer radiation detector. The technique includes a charge-integrating photodetector layer provided in conjunction with a photon-counting photodetector layer. In one embodiment, a plurality of photon-counting photosensor elements are disposed adjacent to a plurality of charge-integrating photosensor elements of the respective layers. Both sets of elements are connected to readout circuitry and a data acquisition system. The detector arrangement may be used for energy discriminating computed tomography imaging and similar computed tomography systems.

An X-ray diffraction and X-ray fluorescence instrument for analyzing samples having no sample preparation includes a X-ray source configured to output a collimated X-ray beam comprising a continuum spectrum of X-rays to a predetermined coordinate and a photon-counting X-ray imaging spectrometer disposed to receive X-rays output from an unprepared sample disposed at the predetermined coordinate upon exposure of the unprepared sample to the collimated X-ray beam. The X-ray source and the photon-counting X-ray imaging spectrometer are arranged in a reflection geometry relative to the predetermined coordinate.

A fluorescent signal analyzing apparatus includes an image input unit, a storage unit, an extracting unit, and an analyzing unit. At least one fluorescent image of a sample is input to the input unit. The storage unit stores data on the at least one fluorescent image input to the image input unit. The extracting unit extracts, for each of the fluorescent images, data on a fluorescence intensity in a desired region on the at least one fluorescent image from the data on the at least one fluorescent image stored in the storage unit. The analyzing unit calculates at least one of a correlation and a photon counting histogram for the desired region by use of the data on the fluorescence intensity.

A method for correcting at least one of pileup effects or charge sharing effects in multi-cell photon counting detectors includes determining a correction coefficient using a count rate of an entire spectrum and applying the determined correction to the counts recorded in an energy window of interest.

Methods and means for measuring and adjusting the gain of a photomultiplier tube (PMT), or other photo-detector with electron multiplication gain, for the purpose of achieving accurate light measurement, such as in a luminescent radiation dosimeter reader. With a PMT illuminated by a light emitting diode or other light source, the PMT output signal is measured in two modes, signal integration and photon pulse counting. The measured PMT gain is calculated as the ratio of the integrated signal to the photon pulse count. The PMT high voltage may be adjusted to cause the measured PMT gain to correspond to an established calibration gain value, or the data from the PMT may be adjusted to compensate the deviation of the measured PMT gain from the calibration gain value. The light source may be a controllable light source that can be adjusted to provide a specific photon count rate output as measured by the PMT. This invention provides for maintaining light measurement calibration without requiring temperature stabilization or a fixed light source.

A data acquisition system includes a charge-sensitive amplifier (CSA) configured to receive a charge from an x-ray detector, the CSA includes a high-gain electronic voltage amplifier, an electrical energy storage device coupled with the amplifier, and an electrical resistor coupled with the amplifier. The data acquisition system includes a baseline sampling circuit configured to receive an output from the CSA and to sample a baseline signal from the CSA, at least one discriminator coupled to an output of the CSA and to an output of the baseline sampling circuit, the at least one discriminator configured to output a voltage if the output of the CSA exceeds a threshold, and a counter coupled to an output of the discriminator and configured to output a digital signal indicative of a photon count received at the x-ray detector and based on the output from the CSA and on the signal from the CSA.

A system for time-correlated photon counting. The system uses one or more photon detectors to produce electrical pulses corresponding to photons read from a target. The system uses a discriminator with a first input coupled to a trigger output from a pulsed optical source and a second input for receiving the electrical pulses. A time-to-pulse height converter is used for producing a series of difference signals each with a respective maxima and whose magnitude is related to the time difference between the trigger output and the electrical pulses. In addition, the system employs a pulse shaping electronic circuit for receiving pulsed electrical output and producing a series of one or more characteristic signals. An A/D converter with a first input receives the difference signals and a second input receives part of the characteristic signals. The A/D converter produces a first series of digital signals representing the difference signals and a second series of digital signals representing the characteristics signals. The results of the A/D converter are feed to a multichannel analyzer for time-shifting the first series of digital signals based on at the second series of digital signals so that the maxima for any given difference signals occurs at the same time as the maxima for at least one other part of the series of the difference signals.

A CT imaging system includes a rotatable gantry having an opening to receive an object to be scanned, a first x-ray emission source attached to the rotatable gantry and configured to emit x-rays toward the object, and a second x-ray emission source attached to the rotatable gantry and configured to emit x-rays toward the object. A first detector is configured to receive x-rays that emit from the first x-ray emission source, and a second detector configured to receive x-rays that emit from the second x-ray emission source. A first portion of the first detector is configured to operate in an integration mode and a first portion of the second detector is configured to operate in at least a photon-counting mode.

A time correlated single photon counting system having a programmable delay generator triggered by a laser fire event detector. The system may be used for chemical agent detection based on Rayleigh scattering using optical time domain reflectometry techniques. The system may also be used for Raman detection using frequency to time transformations.

An X-ray apparatus is provided for acquisition of images containing spectral information. An X-ray source and a collimator having multiple slits are operable together with a set of line detectors, the line detectors including linear arrays of photon counting channels. Each of the channels includes a photon conversion channel element which is operable to convert photons to electric pulses. A plurality of pulse counters are operable to count pulses in a plurality of different ranges of pulse strength, where the strength of a pulse depends on the energy of the photon. Further, an arrangement is included for an energy subtracting operation.

A method for analyzing/monitoring the properties of species that are labeled with fluorophores. A detector is used to detect photons emitted from species that are labeled with one or more fluorophores and located in a confocal detection volume. The arrival time of each of the photons is determined. The interval of time between various photon pairs is then determined to provide photon pair intervals. The number of photons that have arrival times within the photon pair intervals is also determined. The photon pair intervals are then used in combination with the corresponding counts of intervening photons to analyze properties and interactions of the molecules including brightness, concentration, coincidence and transit time. The method can be used for analyzing single photon streams and multiple photon streams.

A method for single photon counting transmission computed tomography (CT) is described. The method is based on an apparatus consisting of a radiation source and detectors on an opposite side of the subject from the source. The radiation source is for example an X-ray tube. The detectors are independently connected to parallel, fast, low-noise processing electronics capable of recording and counting individual X-ray photons at very high rate. In one embodiment of the invention, said detector is made of a scintillator coupled to a photodetector. The photodetector can be an avalanche photodiode (APD). The method comprises the steps of: directing the low energy radiation source toward the subject; detecting the radiation transmitted through the subject towards the detectors and recording the position and energy of each individual X-ray photon; rotating the radiation source and detectors around the subject; recording data for each position of the radiation source and detectors around the subject to form projections; and creating a CT image from the recorded projection data. The proposed method allows enhancing CT image contrast and reducing radiation dose to the patient by counting individual X-ray photons.

Following exposure to an external light source, determining: 1) the fertility of an avian egg by measuring the photon intensity (photons per second) of the egg's biophoton and luminescence; and 2) the gender of an avian egg by measuring the photon spectrum of the egg's biophoton emission and luminescence. The external light source is either an incandescent, fluorescent, LED, (pulsed or continuous wave) monochromatic or dichromatic laser light source. The detector of the photon intensity is either a low light sensing photomultiplier tube (PMT), silicon based photon counting sensor, or Geiger-mode avalanche photodiode detector. The detector of the photon spectrum is a spectrometer. Following exposure to the referenced light sources, fertile avian eggs will exhibit a higher intensity of photons than that of unfertilized avian eggs, and avian eggs of the female gender will emit a different spectrum of photons than will avian eggs of the male gender.

An imaging system includes an x-ray source, a detector that receives x-rays emitted from the x-ray source, a DAS configured to count photon hits in the detector that occur at photon energies above at least a low keV threshold, a medium keV threshold, and a high keV threshold, and a computer operably coupled to the DAS. The computer is programmed to vary each of the medium keV threshold and the high keV threshold over a continuous keV range during data acquisition to define low, medium, and high keV bins that are based on the low, medium, and high keV thresholds, obtain photon counts in the low, medium, and high keV bins in a plurality of keV threshold combinations, calculate a noise variance as a function of at least one of the keV thresholds, and identify a noise minimum and low, medium, and high keV thresholds that correspond thereto.