Showing papers on "Dynamic range published in 2017"

Full Dynamic-Range Pressure Sensor Matrix Based on Optical and Electrical Dual-Mode Sensing.

Abstract: A pressure-sensor matrix (PSM) with full dynamic range can accurately detect and spatially map pressure profiles. A 100 × 100 large-scale PSM gives both electrical and optical signals by itself without applying an external power source. The device represents a major step toward digital imaging, and the visible display of the pressure distribution covers a large dynamic range.

A High Dynamic-Range Neural Recording Chopper Amplifier for Simultaneous Neural Recording and Stimulation

Abstract: Closed-loop neuromodulation is essential for the advance of neuroscience and for administering therapy in patients suffering from drug-resistant neurological conditions. Neural stimulation generates large artifacts at the recording sites, which easily saturate traditional recording front ends. This paper presents a neural recording chopper amplifier capable of handling in-band artifacts up to 40 mVpp while preserving the accompanying small neural signals. New techniques have been proposed that solve the issues of low input impedance and electrode-offset rejection, which enable a DC input impedance of 300 MΩ and a dynamic range of 69 dB (200 Hz-5 kHz) and 78 dB (1-200 Hz). Implemented in a 40-nm CMOS process, the prototype occupies an area of 0.071 mm2/channel, and consumes 2 μW from a 1.2 V supply. The input-referred noise is 7 μV rms (200 Hz-20 kHz) and 2 μV rms (1-200 Hz). The total harmonic distortion for a 20-mV p input at 1 kHz is -74 dB. This paper improves the linearity by 14-26 dB, dynamic range by 11-28 dB, and input-impedance for chopped front ends by a factor of 11 as compared with the current state of the art, while achieving similar power and noise performance.

Charge-integrating organic heterojunction phototransistors for wide-dynamic-range image sensors

Abstract: Solution-processed phototransistors can substantially advance the performance of image sensors. Phototransistors exhibit large photoconductive gain and a sublinear responsivity to irradiance, which enables a logarithmic sensing of irradiance that is akin to the human eye and has a wider dynamic range than photodiode-based image sensors. Here, we present a novel solution-processed phototransistor composed of a heterostructure between a high-mobility organic semiconductor and an organic bulk heterojunction. The device efficiently integrates photogenerated charge during the period of a video frame then quickly discharges it, which significantly increases the signal-to-noise ratio compared with sampling photocurrent during readout. Phototransistor-based image sensors processed without photolithography on plastic substrates integrate charge with external quantum efficiencies above 100% at 100 frames per second. In addition, the sublinear responsivity to irradiance of these devices enables a wide dynamic range of 103 dB at 30 frames per second, which is competitive with state-of-the-art image sensors. A solution-processed organic phototransistor is operated at 100-frame-per-second rates with external quantum efficiencies above 100%. Dynamic range as high as 103 dB was shown for 30-frame-per-second operation.

Multi-event waveform-retrieved distributed optical fiber acoustic sensor using dual-pulse heterodyne phase-sensitive OTDR.

Abstract: We demonstrate a novel type of distributed optical fiber acoustic sensor, with the ability to detect and retrieve actual temporal waveforms of multiple vibration events that occur simultaneously at different positions along the fiber. The system is realized via a dual-pulse phase-sensitive optical time-domain reflectometry, and the actual waveform is retrieved by heterodyne phase demodulation. Experimental results show that the system has a background noise level as low as 8.91×10−4 rad/√Hz with a demodulation signal-to-noise ratio of 49.17 dB at 1 kHz, and can achieve a dynamic range of ∼60 dB at 1 kHz (0.1 to 104 rad) for phase demodulation, as well as a detection frequency range from 20 Hz to 25 kHz.

A kilo-pixel imaging system for future space based far-infrared observatories using microwave kinetic inductance detectors

Abstract: spectrum will require very large arrays of ultra-sensitive detectors in combination with high multiplexing factors and effcient lownoise and low-power readout systems. We have developed a demonstrator system suitable for such applications. Methods. The system combines a 961 pixel imaging array based upon Microwave Kinetic Inductance Detectors (MKIDs) with a readout system capable of reading out all pixels simultaneously with only one readout cable pair and a single cryogenic amplifier. We evaluate, in a representative environment, the system performance in terms of sensitivity, dynamic range, optical efficiency, cosmic ray rejection, pixel-pixel crosstalk and overall yield at an observation centre frequency of 850 GHz and 20% fractional bandwidth. Results. The overall system has an excellent sensitivity, with an average detector sensitivity hNEPdeti = 3 - 10

Multi-Purpose Fully Differential 61- and 122-GHz Radar Transceivers for Scalable MIMO Sensor Platforms

Abstract: This paper describes a multi-purpose radar system suitable for applications with different requirements on dynamic range, resolution, and miniaturization degree. It utilizes a scalable sensor platform that includes a wideband 30.5-GHz voltage-controlled oscillator (VCO) as well as 61- and 122-GHz transceivers (TRXs) in a silicon-germanium BiCMOS technology. The proposed architecture enables the cascading of multiple TRXs and allows the implementation of MIMO radar systems in two different frequency bands by using a single VCO. The higher transmit output power of 11.5 dBm as well as receive gain of 24 dB make the 61-GHz TRX suitable for applications requiring a high dynamic range. The lower wavelength allows the integration of on-chip antennas in the 122-GHz TRX and enables, thus, a high miniaturization degree. The higher LO scaling factor makes the 122-GHz TRX also more attractive for high-resolution applications. A sweep bandwidth of 2.5 GHz generated by the VCO is scaled up to 10 GHz and results in a range resolution of 3 cm. The proposed TRXs are equipped with binary phase shift keying modulators as well as an I/Q receiver and can be utilized to build a flexible software-defined radar platform for range and distant-selective vibration sensors utilizing frequency-modulated continuous wave as well as pseudo-random noise radar techniques.

Sub-ppb nitrogen dioxide detection with a large linear dynamic range by use of a differential photoacoustic cell and a 3.5 W blue multimode diode laser

Abstract: A sub-ppb level photoacoustic spectroscopy (PAS)-based sensor for nitrogen dioxide (NO2) detection was developed by means of a 3.5 W CW multimode diode laser emitting at 447 nm. A differential photoacoustic cell was designed to match the imperfect laser beam and reduce the external acoustic as well as the electromagnetic noise. The diode laser power, gas flow and pressure of the sensor were optimized, which resulted in a NO2 sensor system with a detection limit of 54 pptv with a 1-s averaging time and an excellent linear dynamic range over > three orders of magnitude. The impact of water vapor as the catalyst on the photoacoustic signal amplitude was also investigated. Continuous measurements covering an eight-day period were performed to demonstrate the stability and robustness of the reported PAS-based NO2 sensor system.

Dynamic range expansion based on image statistics

Abstract: As the dynamic range of displays keeps increasing, there is a need for reverse tone mapping methods, which aim at expanding the dynamic range of legacy low dynamic range images for viewing on higher dynamic range displays. While a number of strategies have been proposed, most of them are designed for well-exposed input images and are not optimal when dealing with ill-exposed (under- or over-exposed) content. Further, this type of content is more prone to artifacts which may arise when using local methods. In this work, we build on an existing, automatic, global reverse tone mapping operator based on a gamma expansion. We improve this method by providing a new way for automatic parameter calculation from the image statistics. We show that this method yields better results across the whole range of exposures.

A Dynamic Zoom ADC With 109-dB DR for Audio Applications

Abstract: This paper presents the first dynamic zoom ADC. Intended for audio applications, it achieves 109-dB DR, 106-dB signal-to-noise ratio, and 103-dB SNDR in a 20-kHz bandwidth, while dissipating only 1.12 mW. This translates into the state-of-the-art energy efficiency as expressed by a Schreier FoM of 181.5 dB. It also achieves the state-of-the-art area efficiency, occupying only 0.16 mm2 in the 0.16- $\mu \text{m}$ CMOS. These advances are enabled by the use of concurrent fine and coarse conversions, dynamic error-correction techniques, and a dynamically biased inverter-based operational transconductance amplifier.

Pixel-by-pixel local dimming for high-dynamic-range liquid crystal displays

Abstract: We propose a high dynamic range (HDR) liquid crystal display (LCD) with pixel-level local dimming. The device structure consists of a pixelated LCD dimming panel to control the backlight intensity entering the master LCD panel. According to our analysis and test cell experiment, this dual-panel display system possesses exceedingly high contrast ratio (> 1,000,000:1) and high bit-depth (> 14 bits) at merely 5 volts. Meanwhile, to mitigate the Moire effect induced by the cascaded thin-film transistor (TFT) backplanes, we separate the two LCD panels with a polarization-dependent scattering film. The pros and cons of this HDR display are discussed.

Ultrahigh-Resolution Optical Vector Analysis Based on Optical Single-Sideband Modulation

Abstract: Knowing magnitude, phase, and polarization responses is of great importance for fabrication and application of optical devices. A large variety of parameters such as insertion loss, dispersion, group delay, polarization-dependent loss, and polarization mode dispersion can be obtained based on these responses. Conventional approaches achieve the optical spectral responses by sweeping the wavelength of a laser source. Restricted by the low-wavelength accuracy and poor wavelength stability of the wavelength-swept laser source, the resolution of the optical vector analyzers (OVAs) are usually poor (>1.6 pm). To achieve ultrahigh resolution measurement, an OVA based on optical single-sideband (OSSB) modulation has been proposed and developed, which potentially has a sub-Hz resolution. However, electrical-to-optical and optical-to-electrical conversions are required to implement the electrical frequency sweeping and to detect the phase and magnitude information in the electrical domain, which limits the spectral measurement range, accuracy, and dynamic range. In the past decade, great efforts have been devoted to deal with these problems. In this paper, techniques for constructing high-performance OSSB-based OVAs are discussed with an emphasis on the system architectures and operation principles for improving the spectral measurement range, accuracy, and dynamic range of the measurement system. Possible future research directions are also discussed.

High dynamic, high resolution and wide range single shot temporal pulse contrast measurement.

Abstract: A novel apparatus for the single-shot measurement of the temporal pulse contrast of modern ultra-short pulse lasers is presented, based on a simple yet conceptual refinement of the self-referenced spectral interferometry (SRSI) approach The introduction of the spatial equivalent of a temporal delay by tilted beams analyzed with a high quality imaging spectrometer, enables unprecedented performance in dynamic, temporal range and resolution simultaneously Demonstrated consistently in simulation and experiment at the front-end of the PW laser Draco, the full range of the ps temporal contrast defining the quality of relativistic laser-solid interaction could be measured with almost 80 dB dynamic range, 18ps temporal window, and 18fs temporal resolution Additionally, spatio-temporal coupling as in the case of a pulse front tilt can be quantitatively explored

Continuous-wave 1550 nm operated terahertz system using ErAs:In(Al)GaAs photo-conductors with 52 dB dynamic range at 1 THz

Abstract: Telecom-wavelength compatible photoconductors benefit strongly from the large amount and affordability of telecom lasers and components but there are demanding requirements on material development. We demonstrate continuous-wave (CW) photomixing with a setup that only uses ErAs:In(Al)GaAs devices with a peak dynamic range (DNR) of 78 dB and a bandwidth of ∼3.65 THz at an integration time of 300 ms and only 26 mW laser power on each device. The ErAs:InGaAs receiver further features a factor of two lower noise equivalent power (NEP) than a state-of-the-art photoconductor, despite an antenna mismatch.

A 1.4-m $\Omega$ -Sensitivity 94-dB Dynamic-Range Electrical Impedance Tomography SoC and 48-Channel Hub-SoC for 3-D Lung Ventilation Monitoring System

Abstract: A wearable electrical impedance tomography (EIT) system is proposed for the portable real-time 3-D lung ventilation monitoring. It consists of two types of SoCs, active electrode (AE)-SoC and Hub-SoC, mounted on wearable belts. The 48-channel AE-SoCs are integrated on flexible printed circuit board belt, and Hub-SoC is integrated in the hub module which performs data gathering and wireless communication between an external imaging device. To get high accuracy under the variation of conductivity, the dual-mode current stimulator provides the optimal frequency for time difference-EIT and frequency difference-EIT with simultaneous 4 k–128 kHz impedance sensing. A wide dynamic range instruments amplifier is proposed to provide 94 dB of wide dynamic range impedance sensing. In addition, the 48-channel AE system with the dedicated communication and calibration is implemented to achieve 1.4- $\text{m}\Omega $ sensitivity of impedance difference in the in vivo environment. The AE-/Hub-SoCs occupy 3.2 and 1.3 mm2 in 65-nm CMOS technology and consume $124~\mu \text{W}$ and 1.1 mW with 1.2 V supply, respectively. As a result, EIT images are reconstructed with 90% of accuracy, and up to 10 frames/s real-time 3-D lung images are successfully displayed.

Strain Dynamic Range Enlargement of Slope-Assisted BOTDA by Using Brillouin Phase-Gain Ratio

Abstract: A novel technique to enlarge the dynamic range of strain measurement for slope-assisted Brillouin optical time domain analysis (SA-BOTDA) is proposed by introducing a new parameter called Brillouin phase-gain ratio, which combines Brillouin phase shift and Brillouin gain. With the new technique, the dynamic range of strain measurement can be enlarged, and the pump-power-dependency problem mitigated. In the experiment, a 100-MHz frequency span of linear slope is demonstrated with a 25-ns pump pulse, which is 3.3 times of that in conventional SA-BOTDA, and a dynamic strain with a large amplitude of about 1000 μe is successfully measured.

A 2-GS/s 8-bit Time-Interleaved SAR ADC for Millimeter-Wave Pulsed Radar Baseband SoC

Abstract: This paper presents a 2-GS/s 8-bit 16 $\times$ time-interleaved (TI) analog-to-digital converter (ADC) for a millimeter-wave pulsed radar baseband system-on-chip (SoC). To suppress sampling timing errors among sub-ADCs, a foreground timing-skew calibration technique with small additional circuits is proposed. Measured spurious-free dynamic range and signal-to-noise distortion ratio at 1-GHz full Nyquist is, therefore, enhanced by 16 and 11 dB, respectively. Unlike conventional calibration techniques based on redundant ADCs or complicated digital calculations, additional circuit components are only several small resistors and a capacitor, resulting in only 0.4% area penalty. This area saving enables the compact integration of the radar baseband SoC with digital beamforming, where eight-channel TI-ADCs occupy the dominant chip area otherwise. Even though this is foreground, no system performance is sacrificed because the calibration sequence is closed loop and fast enough to be executed during an existing calibration interval in a periodic beam transmission sequence. The TI-ADCs are embedded on industrial SoC in a 40-nm CMOS process. The power consumption including the input buffer and the reference buffer is 54.2 mW from a 1.1-V supply, and figure of merit is 355 fJ/conversion step.

High-speed microstrip multi-anode multichannel plate detector system

Abstract: High-speed detector systems with high dynamic range and pulse width characteristics in the sub-nanosecond regime are mandatory for high resolution and highly sensitive time-of-flight mass spectrometers. Typically, for a reasonable detector area, an impedance-matched anode design is necessary to transmit the registered signal fast and distortion-free from the anode to the signal acquisition system. In this report, a high-speed microstrip multi-anode multichannel plate detector is presented and discussed. The anode consists of four separate active concentric anode segments allowing a simultaneous readout of signal with a dynamic range of about eight orders of magnitude. The impedance matched anode segments show pulse width of about 250 ps, measured at full width at half maximum, and rise time of ∼170 ps, measured with an oscilloscope with a sampling rate of 20 GS/s and 4 GHz analogue bandwidth. The usage of multichannel plates as signal amplifier allowed the design of a lightweight, low power consuming, and compact detector system, suitable, e.g., for the integration into space instrumentation or portable systems where size, weight, and power consumption are limited parameters.

No-scanning 3D measurement method using ultrafast dimensional conversion with a chirped optical frequency comb.

Abstract: A simultaneously high-precision, wide-range, and ultrafast time-resolution one-shot 3D shape measurement method is presented. Simultaneous times of flight from multiple positions to a target encoded in a chirped optical frequency comb can be obtained from spectral interferometry. We experimentally demonstrate a one-shot imaging profile measurement of a known step height of 480 µm with µm-level accuracy. We further demonstrate the extension of the dynamic range by measuring in one shot a large step height of 3 m while maintaining high accuracy using the accurate pulse-to-pulse separation of the optical frequency comb. The proposed method with its large dynamic range and measurement versatility can be applied to a broad range of applications, including microscopic structures, objects with large size or aspect ratio, and ultrafast time-resolved imaging. This study provides a powerful and versatile tool for 3D measurement, where various ranges of measurement performances can be tailored to demand.

An 84 dB dynamic range 62.5–625 kHz bandwidth clock-scalable noise-shaping SAR ADC with open-loop integrator using dynamic amplifier

Abstract: This paper proposes a noise shaping SAR ADC with open-loop integrator using dynamic amplifier. The proposed integrator for a delta-sigma modulator requires low-gain open-loop amplifiers, therefore low power dynamic amplifier can be used. Moreover, binary-mode dynamic element matching is proposed to overcome the nonlinearity of a capacitor DAC. An SNDR of 83.5 dB, a power consumption 273.4 μW, and a Schreier figure of merit of 173 dB with a bandwidth of 250 kHz is achieved. In addition, clock scalability has been confirmed for a wide sampling-rate range of 2.5 MS/s to 25 MS/s.

Stabilized Fiber-Optic Fabry–Perot Acoustic Sensor Based on Improved Wavelength Tuning Technique

Abstract: A fiber-optic Fabry–Perot acoustic sensor system based on an improved wavelength tuning stabilization technique is presented. The stabilization is achieved by wavelength periodically tuning using a tunable distributed feedback laser. The performance of the developed sensor system was verified by tests. Experimental results demonstrate that the sensitivity, the dynamic range, and the min detectable sound pressure level (SPL) are 92 mV/Pa, 96 dB, and 7 dB-SPL at 1 kHz, respectively. The sensor is suitable for weak acoustic sensing.

Demonstration of Real-Time Burst-Mode Digital Coherent Reception With Wide Dynamic Range in DSP-Based PON Upstream

Abstract: This paper proposes a real-time burst-mode coherent receiver (BMCR) that enables wide dynamic range reception for future passive optical network (PON) applications, wherein two key burst-mode components are implemented; an automatic gain controlled semiconductor optical amplifier (AGC-SOA) for optical power equalization and a real-time digital signal processor (DSP) with a frame detection (FD) function. The AGC-SOA greatly increases the receiver dynamic range by reducing the impact of quantization errors in the analogue-to-digital conversion used for DSP-based signal demodulation while the FD function detects burst frame arrivals for frame-by-frame optimization of tap weights of an adaptive filter in the DSP. Successful real-time reception of 20 Gb/s single polarization quadrature phase shift keying burst signals with wide dynamic range of 22.0 dB is experimentally demonstrated. New system configurations of the DSP-based coherent PONs using the BMCR and wavelength plans assigned to the new systems are also proposed to offer a smooth migration from existing PONs.

Comparison of linear intrascan and interscan dynamic ranges of Orbitrap and ion-mobility time-of-flight mass spectrometers.

Abstract: Rationale The linear intrascan and interscan dynamic ranges of mass spectrometers are important in metabolome and residue analysis. A large linear dynamic range is mandatory if both low and high abundance ions have to be detected and quantitated in heavy matrix samples. These performance criteria, as provided by modern high resolution mass spectrometry, were systematically investigated. Methods The comparison included two generations of Orbitraps, and an ion mobility quadrupole time-of-flight (Q-TOF) system In addition, different scan modes, as provided by the utilized instruments, were investigated. Calibration curves of different compounds covering a concentration range of five orders of magnitude were measured to evaluate the linear interscan dynamic range. The linear intrascan dynamic range and the resulting mass accuracy were evaluated by repeating these measurements in the presence of a very intense background. Results Modern HRMS instruments can show linear dynamic ranges of five orders of magnitude. Often, however, the linear dynamic range is limited by the detection capability (sensitivity and selectivity) and by the electrospray ionization. Orbitraps, as opposed to TOF instruments, show a reduced intrascan dynamic range. This is due to the limited C-trap and Orbitrap capacity. The tested TOF instrument shows poorer mass accuracies than the Orbitraps. In contrast, hyphenation with an ion mobility device seems not to affect the linear dynamic range. Conclusions The linear dynamic range of modern high-resolution mass spectrometry (HRMS) instrumentation has been significantly improved. This also refers to the virtual absence of systematic mass shifts at high ion abundances. The intrascan dynamic range of the current Orbitrap technology may still be a limitation when analyzing complex matrix extracts. On the other hand, the linear dynamic range is not only limited by the detector technology but can also be shortened by peripheral devices, where the ionization and transfer of ions take place.

Towards large dynamic range and ultrahigh measurement resolution in distributed fiber sensing based on multicore fiber.

Abstract: Featuring a dependence of Brillouin frequency shift (BFS) on temperature and strain changes over a wide range, Brillouin distributed optical fiber sensors are however essentially subjected to the relatively poor temperature/strain measurement resolution. On the other hand, phase-sensitive optical time-domain reflectometry (Φ-OTDR) offers ultrahigh temperature/strain measurement resolution, but the available frequency scanning range is normally narrow thereby severely restricts its measurement dynamic range. In order to achieve large dynamic range and high measurement resolution simultaneously, we propose to employ both the Brillouin optical time domain analysis (BOTDA) and Φ-OTDR through space-division multiplexed (SDM) configuration based on the multicore fiber (MCF), in which the two sensors are spatially separately implemented in the central core and a side core, respectively. As a proof of concept, the temperature sensing has been performed for validation with 2.5 m spatial resolution over 1.565 km MCF. Large temperature range (10 °C) has been measured by BOTDA and the 0.1 °C small temperature variation is successfully identified by Φ-OTDR with ~0.001 °C resolution. Moreover, the temperature changing process has been recorded by continuously performing the measurement of Φ-OTDR with 80 s frequency scanning period, showing about 0.02 °C temperature spacing at the monitored profile. The proposed system enables the capability to see finer and/or farther upon requirement in distributed optical fiber sensing.

Superconducting Nonlinear Kinetic Inductance Devices

Abstract: We describe a novel class of devices based on the nonlinearity of the kinetic inductance of a superconducting thin film. By placing a current-dependent inductance in a microwave resonator, small currents can be measured through their effect on the resonator’s frequency. By using a high-resistivity material for the film and nanowires as kinetic inductors, we can achieve a large coefficient of nonlinearity to improve device sensitivity. We demonstrate a current sensitivity of 8 pA/√Hz, making this device useful for transition-edge sensor (TES) readout and other cutting-edge applications. An advantage of these devices is their natural ability to be multiplexed in the frequency domain, enabling large detector arrays for TES-based instruments. A traveling-wave version of the device, consisting of a thin-film microwave transmission line, is also sensitive to small currents as they change the phase length of the line due to their effect on its inductance. We demonstrate a current sensitivity of 5 pA/√Hz for this version of the device, making it also suitable for TES readout as well as other current-detection applications. It has the advantage of multi-gigahertz bandwidth and greater dynamic range, offering a different approach to the resonator version of the device. Finally, we also demonstrate a transmission-line resonator version of the device that combines some of the advantages of the nanowire resonator and the traveling-wave device. This version of the device has high dynamic range but can also be easily multiplexed in the frequency domain. A lumped-element resonator similar to the first device can be placed in a loop configuration to make it sensitive to magnetic fields. We demonstrate an example of such a device whose sensitivity could ultimately reach levels similar to those of state-of-the-art DC SQUIDs, making it potentially useful for many magnetometry applications given its ease of multiplexing. Finally, a similar microwave resonator is shown to exhibit parametric gain of up to 29 dB in the presence of a strong pump tone. The noise performance of this parametric amplifier approaches the quantum limit, making it useful for applications in quantum information and metrology.

Design and Self-Noise of MET Closed-Loop Seismic Accelerometers

Abstract: Molecular electronic transfer (MET) technology offers an alternative approach for the development of accelerometers with high dynamic range and low self-noise. The best performance is achieved by using a force-balancing feedback. However, the operating principles of the feedback sensors has not been reporting yet, also, there is not any comprehensive theoretical model describing sensor noise in the complete operating frequency range. This paper reports on the development of the feedback system for an MET seismic accelerometer, a feedback stability analysis, and an optimization of the signal conditioning feedback electronics to get the highest dynamic range. Also, both the theoretical model and experimental results of such sensors self-noise are presented in the range of 0.1–120 Hz. According to the model and the experimental observation, there are two major contributors into self-noise: convective processes in the electrolyte and electronic noise of the signal operational amplifiers. The research results give better understanding of the molecular electronic accelerometers noise nature and suggest ways to reduce it.

High Dynamic Range X-Ray Detector Pixel Architectures Utilizing Charge Removal

Abstract: Several charge integrating CMOS pixel front ends utilizing charge removal techniques have been fabricated to extend dynamic range for X-ray diffraction applications at synchrotron sources and X-ray free electron lasers (XFELs). The pixels described herein build on the mixed mode pixel array detector (MM-PAD) framework, developed previously by our group to perform high dynamic range imaging. These new pixels boast several orders of magnitude improvement in maximum flux over the MM-PAD, which is capable of measuring a sustained flux in excess of $10{^{8}}$ X-rays/pixel/s while maintaining sensitivity to smaller signals, down to single X-rays. To extend dynamic range, charge is removed from the integration node of the front-end amplifier without interrupting integration. The number of times this process occurs is recorded by a digital counter in the pixel. The parameter limiting full well is, thereby, shifted from the size of an integration capacitor to the depth of a digital counter. The result is similar to that achieved by counting pixel array detectors, but the integrators presented here are designed to tolerate a sustained flux $>10{^{11}}$ X-rays/pixel/s. Pixel front-end linearity was evaluated by direct current injection and results are presented. A small-scale readout ASIC utilizing these pixel architectures has been fabricated and the use of these architectures to increase single X-ray pulse dynamic range at XFELs is discussed briefly.

High Precision Laser Scanning of Metallic Surfaces

Abstract: Speckle noise, dynamic range of light intensity, and spurious reflections are major challenges when laser scanners are used for 3D surface acquisition. In this work, a series of image processing operations, that is, Spatial Compound Imaging, High Dynamic Range Extension, Gray Level Transformation, and Most Similar Nearest Neighbor are proposed to overcome the challenges coming from the target surface. A prototype scanner for metallic surfaces is designed to explore combinations of these image processing operations. The main goal is to find the combination of operations that will lead to the highest possible robustness and measurement precision at the lowest possible computational load. Inspection of metallic tools where the surface of its edge must be measured at micrometer precision is our test case. Precision of heights measured without using the proposed image processing is firstly analyzed to be ±7.6 μm at 68% confidence level. The best achieved height precision was ±4.2 μm. This improvement comes at 24 times longer processing time and five times longer scanning time. Dynamic range extension of the image capture improves robustness since the numbers of saturated or underexposed pixels are substantially reduced. Using a high dynamic range (HDR) camera offers a compromise between processing time, robustness, and precision.