Abstract: Disclosed herein is an apparatus comprising: a radiation absorption layer comprising an electrode; a counter; a controller configured to cause a number registered by the counter to change, in response to an absolute value of an electrical signal on the electrode equaling or exceeding an absolute value of a second threshold during a time delay that is started from a time at which the absolute value of the electrical signal equals or exceeds an absolute value of a first threshold.

Abstract: Disclosed herein is a detector having a pixel in a substrate and configured to detect radiation particles incident thereon; a first guard ring in the substrate, surrounding the pixel, and comprising a first doped semiconductor region in the substrate and a first electrically conductive layer in electrical contact to the first doped semiconductor region; a second guard ring in the substrate, surrounding the first guard ring, and comprising a second doped semiconductor region in the substrate and a second electrically conductive layer in electrical contact to the second doped semiconductor region. The first electrically conductive layer overhangs the first doped semiconductor region toward an interior of the first guard ring by a greater extent than the second electrically conductive layer overhangs the second doped semiconductor region toward an interior of the second guard ring.

Abstract: Disclosed herein is an apparatus suitable for detecting X-ray, comprising: an X-ray absorption layer comprising an electrode; an electronics layer, the electronics layer comprising: a substrate having a first surface and a second surface, an electronics system in or on the substrate, an electric contact on the first surface, and a first via extending from the first surface toward the second surface; wherein the electrode is electrically connected to the electric contact; wherein the electronics system comprises a controller connected in series with and between the electric contact and the first via.

Abstract: Disclosed herein is a system comprising: a first X-ray detector in a first layer; a second X-ray detector in a second layer; wherein the first X-ray detector comprises a first X-ray absorption layer and a first electronics layer; wherein the second X-ray detector comprises a second X-ray absorption layer and a second electronics layer; wherein the first X-ray detector is mounted to a first surface of a first printed circuit board; wherein the second X-ray detector is mounted to a first surface of a second printed circuit board, or to a second surface of the first printed circuit board opposite to the first surface of the first printed circuit board; wherein gaps in the second X-ray absorption layer are shadowed by the first X-ray absorption layer.

Abstract: Disclosed herein is a method and apparatus for determining time of arrival of incident photons. The time of arrival may be determined with high time accuracy based on the times a voltage across a capacitor being charged by charge carriers generated from the incident photons at which the voltage reaches a plurality of thresholds, respectively, and the stable value of the voltage.

Abstract: Disclosed herein is a method comprising: attaching a plurality of chips to a substrate, wherein each of the chips comprises only one pixel configured to detect radiation. Disclosed herein is a method comprising: attaching a wafer to a substrate, wherein the substrate comprises discrete electrodes, wherein the wafer comprises a radiation absorption layer and a plurality of electrical contacts, wherein each of the electrical contacts is connected to at least one of the discrete electrodes; identifying a defective area of the wafer; replacing a portion of the wafer with a chip configured to absorb radiation, the portion comprising the defective area.

Abstract: Disclosed herein is a radiation detector, comprising: a radiation absorption layer comprising an electrode; a voltage comparator that compares a voltage of the electrode to a first threshold; a counter that registers a number of photons of radiation absorbed by the radiation absorption layer; a controller; and a voltmeter. The controller is configured to start a time delay from a time at which the voltage comparator determines that an absolute value of the voltage equals or exceeds an absolute value of the first threshold. The controller is configured to cause the voltmeter to measure the voltage upon expiration of the time delay. The controller is configured to determine the number of photons by dividing the voltage measured by the voltmeter by a voltage that a single photon would have caused on the electrode. The controller can cause the number registered by the counter to increase by the number of photons.

Abstract: Disclosed herein is an apparatus comprising: an array of avalanche photodiodes (APDs) or an absorption region comprising a semiconductor single crystal such as a CdZnTe single crystal or a CdTe single crystal. The apparatus may be configured to absorb radiation particles incident on an absorption region of the APDs or the semiconductor single crystal and to generate charge carriers. The apparatus may comprise an electrode comprising silver nanoparticles and being electrically connected to the absorption region of the APDs or the semiconductor single crystal. For the APDs, each of the APDs may comprise an amplification region, which may comprise a junction with an electric field in the junction. The electric field may be at a value sufficient to cause an avalanche of charge carriers entering the amplification region, but not sufficient to make the avalanche self-sustaining. The junctions of the APDs may be discrete.

Abstract: Disclosed herein is an apparatus comprising: a first radiation source configured to produce a first divergent beam of radiation toward an object; a second radiation source configured to produce a second divergent beam of radiation toward the object; and an image sensor. The image sensor, the first radiation source and the second radiation source are configured to rotate around the object, and relative positions among the image sensor, the first radiation source and the second radiation source are fixed during rotation around the object. The method of using the apparatus is also disclosed herein.

Abstract: Disclosed herein is a detector, comprising: a radiation absorption layer comprising an electric contact; a filter electrically connected to the electric contact and configured to attenuate signals from the electric contact below a first cutoff frequency; an integrator electrically connected to the filter and configured to integrate signals from the filter over a period of time.

Abstract: Disclosed herein is a method and apparatus for determining time of arrival of incident photons. The time of arrival may be determined with high time accuracy based on characteristics of the rate of change of a voltage across a capacitor being charged by charge carriers generated from the incident photons.

Abstract: Disclosed herein is an apparatus suitable for light scanning. The apparatus comprises a light source and a photonic crystal. The light source is configured to direct a light beam along an optical axis toward the photonic crystal. The photonic crystal is configured to direct the light beam along a direction at an angle relative to the optical axis. The angle is a function of wavelength of the light beam. The apparatus may also comprise a partial toroid lens configured to diverge the light beam received from the photonic crystal. The light source of the apparatus may be configured to change the wavelength continuously across a range of wavelengths.

Abstract: Disclosed herein is a radiation detector configured to absorb radiation particles incident on a semiconductor single crystal of the radiation detector and to generate positive charge carriers and negative charge carriers in the semiconductor single crystal. The semiconductor single crystal may be a cadmium zinc telluride (CdZnTe) single crystal or a cadmium telluride (CdTe) single crystal. The radiation detector comprises a first electrical contact in electrical contact with the semiconductor single crystal and a second electrical contact surrounding the first electrical contact or the semiconductor single crystal. The first electrical contact is configured to collect the negative charge carriers. The second electrical contact is configured to cause the positive charge carriers to drift out of the semiconductor single crystal.

Abstract: Disclosed herein is a system comprising: an optical system with a focal plane; an apparatus at the focal plane; a filter; wherein the apparatus comprises an array of vertical-cavity surface-emitting lasers (VCSELs) on a first substrate and an array of detectors on a second substrate, the detectors configured to detect laser beams that are emitted by the VCSELs and backscattered by an object; wherein the first substrate is mounted to the second substrate and is configured to allow the laser beams that are emitted by the VCSELs and backscattered by the object to transmit through the first substrate and reach the detectors; wherein the filter is configured to prevent light other than the laser beams from passing.

Abstract: Disclosed herein is a computed tomography system, comprising: a table with a hole therein, wherein the table is configured to support a person lying face down thereon, with at least one of the person's breasts projecting through the hole; an X-ray source; an X-ray detector comprising a plurality of pixels; wherein the X-ray source is configured to rotate around the at least one of the person's breasts.

Abstract: An apparatus suitable for detecting X-ray is disclosed. In one example, the apparatus comprises an X-ray absorption layer comprising a first pixel and a second pixel, and a controller. The controller is configured for determining that carriers generated by a single X-ray photon are collected by the first pixel and the second pixel. The controller is also configured for determining energy of the single X-ray photon based on a first voltage detected from the first pixel and a second voltage detected from the second pixel. The first voltage and the second voltage are caused by the single X-ray photon.

Abstract: Disclosed herein is an X-ray imaging system suitable for detecting x-ray, comprising: a first X-ray detector, and a second X-ray detector; wherein the first X-ray detector is configured to move relative to the second X-ray detector; wherein a spatial resolution of the first X-ray detector is higher than a spatial resolution of the second X-ray detector; wherein a detection area of the first X-ray detector is smaller than a detection area of the second X-ray detector. Also described herein is a method of X-ray imaging using the X-ray imaging system.

Abstract: An apparatus suitable for detecting X-ray is disclosed. In one example, the apparatus comprises an X-ray absorption layer and a controller. The X-ray absorption layer comprises a first pixel and a second pixel. The controller is configured for determining that carriers generated by a first X-ray photon are collected by the first pixel and the second pixel, and resetting signals associated with the carriers collected by the first pixel and the second pixel.

Abstract: Disclosed herein is an apparatus, which comprises an optical waveguide, a first and second waveguide couplers. The optical waveguide may be configured to receive light from an end surface of the optical waveguide. The first waveguide coupler may be coupled, at a first coupling strength, to a first portion of the optical waveguide. The second waveguide coupler may be coupled, at a second coupling strength, to a second portion of the optical waveguide. Attenuation of the light at the first portion is smaller than attenuation of the light at the second portion. The first coupling strength is smaller than the second coupling strength. The first waveguide coupler and the second waveguide coupler each comprises a surface comprising sites configured to attach a probe.

Abstract: Disclosed herein is an apparatus comprising: an insertion tube configured to be inserted into a human; a metal target disposed inside the insertion tube and configured to emit X-ray by receiving radiation.