Showing papers on "Photodiode published in 2001"

Optoelectronics and Photonics: Principles and Practices

Abstract: (NOTE: Each chapter concludes with Questions and Problems.) 1. Wave Nature of Light. Light Waves in a Homogeneous Medium. Refractive Index. Group Velocity and Group Index. Magnetic Field, Irradiance and Poynting Vector. Snell's Law and Total Internal Reflection (TIR). Fresnel's Equations. Multiple Interference and Optical Resonators. Goos-Hanchen and Optical Tunneling. Temporal and Spatial Coherence. Diffraction Principles. 2. Dielectric Waveguides and Optical Fibers. Symmetric Planar Dielectric Slab Waveguide. Modal and Waveguide Dispersion in the Planar Waveguide. Step Index Fiber. Numerical Aperture. Dispersion in Single Mode Fibers. Bit-Rate, Dispersion, Electrical and Optical Bandwidth. The Graded Index Optical Fiber. Light Absorption and Scattering. Attenuation in Optical Fibers. Fiber Manufacture. 3. Semiconductor Science and Light Emitting Diodes. Semiconductor Concepts and Energy Bands. Direct and Indirect Bandgap Semiconductors: E-k Diagrams. pn Junction Principles. The pn Junction Band Diagram. Light Emitting Diodes. LED Materials. Heterojunction High Intensity LEDs. LED Characteristics. LEDs for Optical Fiber Communications. 4. Stimulated Emission Devices Lasers. Stimulated Emission and Photon Amplification. Stimulated Emission Rate and Einstein Coefficients. Optical Fiber Amplifiers. Gas Laser: The He-Ne Laser. The Output Spectrum of a Gas Laser. LASER Oscillation Conditions. Principle of the Laser Diode. Heterostructure Laser Diodes. Elementary Laser Diode Characteristics. Steady State Semiconductor Rate Equation. Light Emitters for Optical Fiber Communications. Single Frequency Solid State Lasers. Quantum Well Devices. Vertical Cavity Surface Emitting Lasers (VCSELs). Optical Laser Amplifiers. Holography. 5. Photodetectors. Principle of the pn Junction Photodiode. Ramo's Theorem and External Photocurrent. Absorption Coefficient and Photodiode Materials. Quantum Efficiency and Responsivity. The pin Photodiode. Avalanche Photodiode. Heterojunction Photodiodes. Phototransistors. Photoconductive Detectors and Photoconductive Gain. Noise in Photodetectors. 6. Photovoltaic Devices. Solar Energy Spectrum. Photovoltaic Device Principles. pn Junction Photovoltaic I-V Characteristics. Series Resistance and Equivalent Circuit. Temperature Effects. Solar Cells Materials, Devices and Efficiencies. 7. Polarization and Modulation of Light. Polarization. Light Propagation in an Anisotropic Medium: Birefringence. Birefringent Optical Devices. Optical Activity and Circular Birefringence. Electro-Optic Effects. Integrated Optical Modulators. Acousto-Optic Modulator. Magneto-Optic Effects. Non-Linear Optics and Second Harmonic Generation. Notation and Abbreviations. Index. CD-ROM: Optoelectronics and Photonics Contents.

A monolithic active pixel sensor for charged particle tracking and imaging using standard VLSI CMOS technology

Abstract: A novel Monolithic Active Pixel Sensor (MAPS) for charged particle tracking made in a standard CMOS technology is proposed. The sensor is a photodiode, which is readily available in a CMOS technology. The diode has a special structure, which allows the high detection efficiency required for tracking applications. The partially depleted thin epitaxial silicon layer is used as a sensitive detector volume. Semiconductor device simulation, using either ToSCA based or 3-D ISE-TCAD software packages shows that the charge collection is efficient, reasonably fast (order of 100 ns), and the charge spreading limited to a few pixels only. A first prototype has been designed, fabricated and tested. It is made of four arrays each containing 64×64 pixels, with a readout pitch of 20 μm in both directions. The device is fabricated using standard submicron 0.6 μm CMOS process, which features twin-tub implanted in a p-type epitaxial layer, a characteristic common to many modern CMOS VLSI processes. Extensive tests made with soft X-ray source ( 55 Fe) and minimum ionising particles (15 GeV/ c pions) fully demonstrate the predicted performances, with the individual pixel noise (ENC) below 20 electrons and the Signal-to-Noise ratio for both 5.9 keV X-rays and Minimum Ionising Particles (MIP) of the order of 30. This novel device opens new perspectives in high-precision vertex detectors in Particle Physics experiments, as well as in other application, like low-energy beta particle imaging, visible light single photon imaging (using the Hybrid Photon Detector approach) and high-precision slow neutron imaging.

III nitrides and UV detection

Abstract: III nitrides have become the most exciting challenge in optoelectronic materials in the last decade. Their intrinsic properties and an intense technological effort have made possible the fabrication of reliable and versatile detectors for short wavelengths. In this work, materials and devices issues are considered to provide a full picture of the advances in nitride UV photodetection. First, basic structures like photoconductors, Schottky, p-i-n and metal-semiconductor-metal photodiodes and phototransistors are compared, with emphasis on their specific properties and performance limitations. The efforts in the design and fabrication of more advanced detectors, in the search for higher quantum efficiency, contrast, signal-to-noise or speed operation, are reviewed afterwards. Metal-insulator-semiconductor diodes, avalanche photodetectors and GaN array detectors for UV imaging are also described. Further device optimization is linked with present materials issues, mainly due to the nitride quality, which is a direct result of the substrate used. The influence of substrates and dislocations on detector behaviour is discussed in detail. As an example of AlGaN photodetector applications, monitoring of the solar UV-B radiation to prevent erythema and skin cancer is presented.

Monolithic capillary electrophoresis device with integrated fluorescence detector.

Abstract: A monolithic capillary electrophoresis system with integrated on-chip fluorescence detector has been microfabricated on a silicon substrate. Photodiodes in the silicon substrate measure fluorescence emitted from eluting molecules. The device incorporates an on-chip thin-film interference filter that prevents excitation light from inhibiting the fluorescence detection. A transparent AZO conducting ground plane is also used to prevent the high electric fields used for the separation from interfering with the photodiode response. Separations of DNA restriction fragments have been performed in these devices with femtogram detection limits using SYBR Green I intercalating dye.

Enhanced photogeneration of carriers in a semiconductor via coupling across a nonisothermal nanoscale vacuum gap

Abstract: Enhanced generation of carriers when a thermophotovoltaic cell is placed in submicron proximity to a heated surface is demonstrated using custom-designed InAs photodiodes and special silicon-based heater chips produced using microelectromechanical system techniques. The short-circuit current of the photocells is shown to increase sharply (up to fivefold) when the spacing between the heater and photodiode surfaces is reduced, while at the same time, the heater temperature decreases, consistent with increased radiative transfer between the two surfaces. By varying the spacing sinusoidally (at up to 1 kHz), it is demonstrated that the increase in the short-circuit current occurs in phase with the decrease in separation, thereby ruling out thermal effects. It is argued that the increase in short-circuit current is due to increased evanescent coupling of blackbody radiation from the hot surface to the cold photocell, consistent with recent theoretical predictions. The demonstration of this effect is the initia...

Phase fluorometric dissolved oxygen sensor

Abstract: The design and performance of a ruggedised dissolved oxygen (DO) probe, which is based on phase fluorometric detection of the quenched fluorescence of an oxygen-sensitive ruthenium complex, is reported. The complex is entrapped in a porous hydrophobic sol–gel matrix that has been optimised for this application. The LED excitation and photodiode detection are employed in a dipstick probe configuration, with the oxygen-sensitive film coated on a disposable PMMA disc, which in turn is designed to guide light into the film by total internal reflection. A key element of the design is the common mode rejection of phase between the signal and reference channels, requiring careful selection of the relevant optoelectronic components. The advantages of the phase fluorometric approach over intensity measurement are highlighted. The phase detection electronics exhibits excellent long-term stability with a temperature coefficient of 0.00087. The sensor response exhibits excellent signal-to-noise ratio (SNR) and reversibility and has been corrected for both temperature and pressure. The limit of detection (LOD) is typically 0.15 hPa or 6 ppb. The sensor has many potential applications but it has been designed primarily for application in waste-water monitoring.

A low-power low-noise ultrawide-dynamic-range CMOS imager with pixel-parallel A/D conversion

Abstract: A CMOS image sensor with pixel-parallel analog-to-digital (A/D) conversion fabricated with different array sizes and photodiode types in a three-metal 0.5-/spl mu/m process is presented. Nominal power dissipation is 40 nW per pixel at V/sub DD/=3.3 V. A/D conversion results from sampling a free-running photocurrent-controlled oscillator to give a first-order /spl Sigma/-/spl Delta/ sequence. The sensor displays dynamic range capability of greater than 150000:1 and exhibits fixed pattern noise correctable to within 0.1% of signal.

Ambient light detection technique for an imaging array

Abstract: This invention is directed to a method and apparatus for determining the level of ambient light impinging on a selected number of pixels in an imaging array where each pixel includes a photodiode. The ambient light may be determined by resetting the pixels in the array and by detecting current flow through the photodiodes in a selected number of the pixels as they are being reset. Alternately, the ambient light may be determined by resetting a selected number of the pixels in the array and by detecting current flow through the photodiodes in the selected number of the pixels as they are being reset. The photodiodes are reset by applying a reverse bias voltage across them and the current flow is detected by measuring the current flow through a resistance in parallel to the selected photodiodes. The selected number of pixels may be divided into one or more groups each having at least one pixel, and the pixels in each group may be arranged in specific patterns within the array. The array may be laid out in rows and columns, and the groups may be located in predetermined rows or columns. When only a selected number of pixels are reset and these pixels are divided into groups, the groups may be sequentially reset to permit differentiation between the groups.

High-performance p-i-n Ge on Si photodetectors for the near infrared: from model to demonstration

Abstract: We have investigated the integration of Ge p-i-n and n-i-p heterojunction photodiodes on Si. Recognizing the crucial role of interface defects at the Ge-Si interface on the performance of photodetectors, we have designed and fabricated high-performance n-i-p Ge photodiodes on p/sup +/-Si substrates. These photodiodes exhibit short-circuit responsivities of 0.3 and 0.2 A/W at 1.3 and 1.55 /spl mu/m, respectively, reverse dark currents of 20 mA/cm/sup 2/ and response times of 800 ps.

Waveguide avalanche photodiode operating at 1.55 μm with a gain-bandwidth product of 320 GHz

Abstract: An In/sub 0.52/Al/sub 0.48/As-In/sub 0.53/Ga/sub 0.47/As waveguide avalanche photodiode with a record gain-bandwidth product of over 320 GHz has been demonstrated. A bandwidth of 28 GHz was achieved at low gains with low excess noise and a quantum efficiency of 16% at 1.55 /spl mu/m.

Area sensor and display apparatus provided with an area sensor

Abstract: An area sensor of the present invention has a function of displaying an image in a sensor portion by using light-emitting elements and a reading function using photoelectric conversion devices. Therefore, an image read in the sensor portion can be displayed thereon without separately providing an electronic display on the area sensor. Furthermore, a photoelectric conversion layer of a photodiode according to the present invention is made of an amorphous silicon film and an N-type semiconductor layer and a P-type semiconductor layer are made of a polycrystalline silicon film. The amorphous silicon film is formed to be thicker than the polycrystalline silicon film. As a result, the photodiode according to the present invention can receive more light.

Laser diode optical transducer assembly for non-invasive spectrophotometric blood oxygenation monitoring

Abstract: A non-invasive near infrared spectrophotometric monitoring transducer assembly includes a housing member, which is adhered directly on a patient's skin. The housing member contains a prism coupled to a flexible and lightweight single core optical light guide, which provides a means of transferring narrow spectral bandwidth light from multiple distant laser diodes of different wavelengths by use of a multi-fiber optic light combining assembly. Different wavelengths are needed to monitor the level of blood oxygenation in the patient. The assembly also contains a planar light guide mounted on the prism located in the housing member, which light guide contacts the patient's skin when the housing member is adhered to the patient's skin. The light guide controls the spacing between the prism and the patient's skin, and therefore controls the intensity of the area on the patient's skin which is illuminated by the laser light. The housing member contains a photodiode assembly, which detects the infrared light at a second location on the skin to determine light absorption. The photodiode assembly is preferably shielded from ambient electromagnetic interference (EMI) by an optically transparent EMI attenuating window. This rigid window placed over the photodiode also provides a planar interface between the assembly and the skin, improving optical coupling and stability as well as reducing the capacitive coupling between skin and the photodiode resulting in further EMI attenuation. The housing may be associated with a disposable sterile hydrogel coated adhesive envelope, or pad, which when applied to the patient's skin will adhere the housing to the patient's skin. The transducer assembly will thus be reusable, and skin-contacting part of the device, i.e., the envelope or pad can be discarded after a single use. The assembly also includes a laser safety interlock means, which is operable to turn off the laser light output in the event that the assembly accidentally becomes detached from the patient's skin.

256-channel bidirectional optical interconnect using VCSELs and photodiodes on CMOS

Abstract: Two-dimensional parallel optical interconnects (2-D-POIs) are capable of providing large connectivity between elements in computing and switching systems Using this technology we have demonstrated a bidirectional optical interconnect between two printed circuit boards containing optoelectronic (OE) very large scale integration (VLSI) circuits The OE-VLSI circuits were constructed using vertical cavity surface emitting lasers (VCSELs) and photodiodes (PDs) flip-chip bump-bonded to a 035-/spl mu/m complementary metal-oxide-semiconductor (CMOS) chip The CMOS was comprised of 256 laser driver circuits, 256 receiver circuits, and the corresponding buffering and control circuits required to operate the large transceiver array This is the first system, to our knowledge, to send bidirectional data optically between OE-VLSI chips that have both VCSELs and photodiodes cointegrated on the same substrate

GaN avalanche photodiodes operating in linear-gain mode and Geiger mode

Abstract: For solar-blind ultraviolet detection, AlGaN avalanche photodiodes (APDs) that operate in Geiger mode can outperform conventional AlGaN photodiodes in sensitivity and should compare favorably to photomultiplier tubes. Toward this goal, we report GaN APDs that operate in the linear-gain mode and in the Geiger mode. The APDs were fabricated from high-quality GaN epitaxial layers grown by hydride vapor phase epitaxy. The GaN layer structure consisted of a Zn-doped /spl pi/ layer, an unintentionally doped n layer, and a Si-doped n+ layer-all on top of a thick GaN unintentionally doped n layer on a sapphire substrate. Capacitance-voltage (C-V) measurements on photodiodes fabricated from some of these layers show that field strengths between 3 and 4 MV/cm are sustainable in the depletion region at voltages slightly below the observed breakdown of /spl sim/80 V. Both mesa-etched and planar devices exhibited avalanche gains of 10 in linear-gain mode and /spl sim/10/sup 6/ in Geiger mode when top illuminated with a 325 nm HeCd laser. Raster measurements of the photoresponse show highly uniform response in gain mode that becomes slightly more inhomogeneous in Geiger mode.

Back-illuminated photodiodes for computed tomography detectors

Abstract: A CT scanner (10) includes a reconstruction processor (42) for reconstructing an image from digital signals from detector arrays (20). Each detector array includes scintillation crystals (22) arranged in an array for converting x-ray radiation into light. An array of back-illuminated photo diodes (24) is mounted beneath the scintillation crystal array for converting the light emitted from the scintillation crystals into electrical charge. The electrical charge from the back-illuminated photodiodes is transmitted via a path (54, 56) orthogonal to the detector array (20) to signal processing circuitry (66). The back-illuminated photodiode has a side (28) which is in optical communication with the crystal array (22) and which is optically transmissive to photons of light emanating from the crystal. The converted electrical charge leaves the photodiode via electrical connections (32, 38) or bump bonds (62, 72) on the photodiode (24). This arrangement allows a plurality of paths (54, 56) through the substrate (52) supporting the photodiode to provide electrical connectivity from the array (20) to processing circuitry (66), reducing or eliminating the bottleneck of electrical leads from conventional arrays.

An asymmetric twin-waveguide high-bandwidth photodiode using a lateral taper coupler

Abstract: We describe a high-bandwidth high-responsivity low-polarization sensitivity p-i-n photodiode based on an integratable asymmetric twin-waveguide structure. Incident light is collected by a diluted large-fiber guide followed by transfer to a thin-coupling waveguide using a low-loss lateral-taper coupler. The light is finally absorbed by the uppermost In/sub 0.53/Ga/sub 0.47/As layer. The device has a responsivity of (0.75/spl plusmn/0.03) ampere per watt and a polarization sensitivity of /spl les/0.4 dB. The measured electrical 3 dB bandwidth is /spl ges/40 GHz. The responsivity is comparable with the best 40-GHz waveguide p-type-intrinsic-n-type photodiodes, while the twin-waveguide design provides a single-epitaxial growth step and a simple means of fabrication with possibility for monolithic integration of the photodiodes with other optical components, such as semiconductor optical amplifiers and in-plane waveguide filters.

X-y address type solid state image sensor and its fabricating method

Abstract: PROBLEM TO BE SOLVED: To solve the problem of such a pixel structure as the incident light is taken into a photodiode through an interconnect layer that a part of light condensed through a microlens is sputtered by the interconnect. SOLUTION: In an X-Y address type solid state image sensor, represented by a CMOS image sensor, an interconnect layer 38 is formed on one side of a silicon layer 31 in which a photodiode layer 37 is formed and visible light is taken in from the other side of the silicon layer 31, i.e., the side opposite to the interconnect layer 38 (rear surface side). Since such a rear surface light receiving type pixel structure is employed, the interconnect layer can be formed without taking account of the light receiving face and the degree of freedom is increased in the interconnection of pixels.

Two-dimensional analysis of double-layer heterojunction HgCdTe photodiodes

Abstract: In this paper, the performance of P-on-n double-layer heterojunction (DLHJ) HgCdTe photodiodes at temperature 77 K is analyzed theoretically. Calculation has been performed for the backside-illuminated configuration. The effect of photodiode base layer geometry on quantum efficiency and R/sub o/A product is analyzed. Also, the effect of lateral collection of diffusion current and photocurrent on photodiode parameters has been shown. Moreover the dependence of the p-n junction position within heterostructure on the band-gap energy profiles and photodiode performance is presented. Finally, the influence of the composition gradient and p-side doping concentration on photodiode parameters is described briefly.

CMOS image sensor and manufacturing method thereof

Abstract: A CMOS image sensor and a manufacturing method thereof are disclosed, by which the sensitivity characteristics of the photodiode and the operation characteristics of the MOS transistor are improved and easy and low-cost manufacturing is realized. The CMOS image sensor comprises a photodiode having a light reception surface covered by a multi-layered antireflection film which is formed by alternately depositing two or more kinds of insulating films whose refractive indexes are different; and at least one MOS transistor having diffusion layers which respectively function as source and drain areas, wherein a silicide layer is formed on each diffusion layer. The photodiode and the MOS transistor are provided on a common substrate and are electrically connected with each other.

High-performance InAs/GaSb superlattice photodiodes for the very long wavelength infrared range

Abstract: We report on the demonstration of high-performance p-i-n photodiodes based on type-II InAs/GaSb superlattices with 50% cut-off wavelength λc=16 μm operating at 80 K. Material is grown by molecular beam epitaxy on GaSb substrates with excellent crystal quality as evidenced by x-ray diffraction and atomic force microscopy. The processed devices show a current responsivity of 3.5 A/W at 80 K leading to a detectivity of ∼1.51×1010 cmHz1/2/W. The quantum efficiency of these devices is about 35% which is comparable to HgCdTe detectors with a similar active layer thickness.

Geometry optimization of interdigitated Schottky-barrier metal–semiconductor–metal photodiode structures

Abstract: The optimum geometry of an interdigitated Schottky-barrier metal–semiconductor–metal photodetector (MSM-PD) is discussed. From the calculated MSM-PD capacitance and transit time of optically generated carriers, the response time and quantum efficiency are evaluated and analysed. We propose a simple scaling rule to achieve the best high-speed response of the MSM detector. The optimum interelectrode spacing for interdigitated MSM-PD has been established. The potential of different semiconductor materials for high-speed MSM detectors is examined.

A CMOS photosensor array for 3D imaging using pulsed laser

Abstract: A 32×2 pixel optical time of flight range sensor in standard 0.5 μm CMOS acquires up to 20k BD-images/s combines CDS, S&H, multiple double short time integration, a high-speed synchronous shutter, and a phase synchronizer enabling exposures <30 ns with <5.2 W/m/sup 2/ NEP. This CMOS imager chip for 3D imaging applications contains a photodiode array and the aforementioned features enable optical TOF measurements of laser pulses reflected from a target. The 42 mm/sup 2/ chip dissipates 330 mW.

The breakdown flash of Silicon Avalance Photodiodes - backdoor for eavesdropper attacks?

Abstract: Silicon avalanche photodiodes are the most sensitive photodetectors in the visible to near infrared region. However, when they are used for single photon detection in a Geiger mode, they are known to emit light on the controlled breakdown used to detect a photoelectron. This fluorescence light might have serious impacts on experimental applications like quantum cryptography or single-particle spectroscopy. We characterized the fluorescence behaviour of silicon avalanche photodiodes in the experimentally simple passive quenching configuration and discuss implications for their use in quantum cryptography systems.

Quantifying spatial localization of optical mapping using Monte Carlo simulations

Abstract: Optical mapping techniques used to study spatial distributions of cardiac activity can be divided into two categories; (1) broad-field excitation method, in which hearts stained with voltage or calcium sensitive dyes are illuminated with broad-field excitation light and fluorescence is collected by image or photodiode arrays; (2) laser scanning method, in which illumination uses a scanning laser and fluorescence is collected with a photomultiplier tube. The spatial localization of the fluorescence signal for these two methods is unknown and may depend upon light absorption and scattering at both excitation and emission wavelengths. We measured the absorption coefficients (/spl mu//sub a/), scattering coefficients (/spl mu//sub s/), and scattering anisotropy coefficients (g) at representative excitation and emission wavelengths in rabbit heart tissue stained with di-4-ANEPPS or co-stained with both Rh237 and Oregon Green 488 BAPTA 1. Monte Carlo models were then used to simulate absorption and scattering of excitation light and fluorescence emission light for both broad-field and laser methods in three-dimensional tissue. Contributions of local emissions throughout the tissue to fluorescence collected from the tissue surface were determined for both methods. Our results show that spatial localization depends on the light absorption and scattering in tissue and on the optical mapping method that is used. A tissue region larger than the laser beam or collecting area of the array element contributes to the optical recordings.

Method of fabricating heterojunction photodiodes integrated with cmos

Abstract: A method in which thin-film p-i-n heterojunction photodiodes are formed by selective epitaxial growth/deposition on pre-designated active-area regions of standard CMOS devices. The thin-film p-i-n photodiodes are formed on active areas (for example n+-doped), and these are contacted at the bottom (substrate) side by the 'well contact' corresponding to that particular active area. There is no actual potential well since that particular active area has only one type of doping. The top of each photodiode has a separate contact formed thereon. The selective epitaxial growth of the p-i-n photodiodes is modular, in the sense that there is no need to change any of the steps developed for the 'pure' CMOS process flow. Since the active region is epitaxially deposited, there is the possibility of forming sharp doping profiles and band-gap engineering during the epitaxial process, thereby optimizing several device parameters for higher performance. This new type of light sensor architecture, monolithically integrated with CMOS, decouples the photo-absorption active region from the MOSFETs, hence the bias applied to the photodiode can be independent from the bias between the source, drain, gate and substrate (well) of the MOSFETs.

Monolithic circuit of active quenching and active reset for avalanche photodiodes

Abstract: It is an integrated circuit capable of determining the quenching and the reset of an avalanche photodiode operating in Geiger mode so as to detect single photons falling on the surface of said photodiode. The circuit scheme used makes possible to reduce the size of the circuit down to a single semiconductor chip, to reduce the power dissipation and to reduce the cost of the circuit, at the same time keeping the performance at good level.

High-resolution CMOS imaging detector

Abstract: A 2.5 cm by 5 cm, 512 by 1024 pixel CMOS photodiode array detector designed specifically for digital radiography will be described. All necessary scanning and readout circuitry is integrated within the detector. The small pixel spacing of 48 µm allows the imager to easily achieve the 10 lp/mm resolution required for the targeted interventional mammography application. Direct coupling to the scintillator and a pixel fill factor of more than 80% leads to high DQE over a large range of exposure values. The detector exhibits very low dark current of about 30 pA/cm 2 at room temperature, which allows for low-noise operation and long integration times. Read noise of less than 200 electrons rms and a saturation level of 2.8x10 6 electrons combine for a large dynamic range greater than 80 dB. The conversion gain of the detector is 0.5 µV/electron. Combined with a Gd 2O2S scintillator, the imager achieves up to 25% MTF at 10 lp/mm and a DC detective quantum efficiency of 50%. The detector design is optimized for x-ray energies between 10 kV and 50 kV, but can be retrofitted with different scintillator screens to cover a large range of imaging applications up to 160 kV.