scholarly journals Characterization of a dual-beam, dual-camera optical imaging polarimeter

2020 ◽  
Vol 494 (4) ◽  
pp. 4676-4686
Author(s):  
Manisha Shrestha ◽  
Iain A Steele ◽  
Andrzej S Piascik ◽  
Helen Jermak ◽  
Robert J Smith ◽  
...  
Keyword(s):  
Optical Imaging ◽  
Data Reduction ◽  
High Sensitivity ◽  
Cmos Technology ◽  
Low Noise ◽  
Reduction Algorithm ◽  
Dual Beam ◽  
Instrumental Polarization ◽  
Transient Sources

ABSTRACT Polarization plays an important role in various time-domain astrophysics to understand the magnetic fields, geometry, and environments of spatially unresolved variable sources. In this paper we present the results of laboratory and on-sky testing of a novel dual-beam, dual-camera optical imaging polarimeter (MOPTOP) exploiting high sensitivity, low-noise CMOS technology, and designed to monitor variable and transient sources with low systematic errors and high sensitivity. We present a data reduction algorithm that corrects for sensitivity variations between the cameras on a source-by-source basis. Using our data reduction algorithm, we show that our dual-beam, dual-camera technique delivers the benefits of low and stable instrumental polarization (<0.05 per cent for lab data and <0.25 per cent for on sky data) and high throughput while avoiding the additional sky brightness and image overlap problems associated with dual-beam, single-camera polarimeters.

Design and Characterization of a Low-Noise Front-End Readout ASIC in 0.18- $\mu$ m CMOS Technology for CZT/Si-PIN Detectors

2018 ◽  
Vol 65 (5) ◽  
pp. 1203-1211 ◽  
Author(s):  
W. Gao ◽  
S. Li ◽  
Y. Duan ◽  
P. Huang ◽  
Z. Li ◽  
...  
Keyword(s):  
Cmos Technology ◽  
Low Noise ◽  
Front End

scholarly journals Commissioning Results of a New Polarimeter: Denver University Small Telescope Polarimeter (DUSTPol)

2014 ◽  
Vol 10 (S305) ◽  
pp. 200-206
Author(s):  
T. M. Wolfe ◽  
R. Stencel ◽  
G. Cole
Keyword(s):  
Data Reduction ◽  
Interaction Parameters ◽  
Small Telescope ◽  
Dual Beam ◽  
Instrumental Polarization ◽  
Active Stars ◽  
Optical Wavelengths

AbstractDUSTPol is a dual-beam polarimeter that operates in optical wavelengths, and was built to promote the study of linear polarimetry with smaller telescopes. DUSTPol's performance has demonstrated low instrumental polarization at 0.05 ± 0.02%. This poster presents commissioning results as well as early science observations, and describes software used for data reduction. Recent polarimetric results of RS CVn systems and Wolf-Rayet stars, discussed herein, indicate shape and interaction parameters. By promoting the development of similar polarimeters at other institutions, DUSTPol will serve to establish new collaborative surveys of cool active stars, as well as systems showing evidence of containing complex stellar environments.

scholarly journals Design and Optimization of a Low Power Pressure Sensor for Wireless Biomedical Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
J. Sosa ◽  
Juan A. Montiel-Nelson ◽  
R. Pulido ◽  
Jose C. Garcia-Montesdeoca
Keyword(s):  
Blood Pressure ◽  
Power Consumption ◽  
Low Power ◽  
Pressure Sensor ◽  
Biomedical Applications ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Cmos Technology ◽  
Low Noise ◽  
Least Significant Bit

A blood pressure sensor suitable for wireless biomedical applications is designed and optimized. State-of-the-art blood pressure sensors based on piezoresistive transducers in a full Wheatstone bridge configuration use low ohmic values because of relatively high sensitivity and low noise approach resulting in high power consumption. In this paper, the piezoresistance values are increased in order to reduce by one order of magnitude the power consumption in comparison with literature approaches. The microelectromechanical system (MEMS) pressure sensor, the mixed signal circuits signal conditioning circuitry, and the successive approximation register (SAR) analog-to-digital converter (ADC) are designed, optimized, and integrated in the same substrate using a commercial 1 μm CMOS technology. As result of the optimization, we obtained a digital sensor with high sensitivity, low noise (0.002 μV/Hz), and low power consumption (358 μW). Finally, the piezoresistance noise does not affect the pressure sensor application since its value is lower than half least significant bit (LSB) of the ADC.

scholarly journals A PVT-Robust Super-Regenerative Receiver with Background Frequency Calibration and Concurrent Quenching Waveform

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1119 ◽  
Author(s):  
Yin ◽  
Fu ◽  
El-Sankary
Keyword(s):  
Data Stream ◽  
Input Data ◽  
Phase Error ◽  
Random Phase ◽  
High Sensitivity ◽  
Cmos Technology ◽  
Low Noise ◽  
Center Frequency ◽  
Noise Performance ◽  
Frequency Calibration

A process-voltage-temperature (PVT)-robust, low power, low noise, and high sensitivity, super-regenerative (SR) receiver is proposed in this paper. To enable high sensitivity and robust-PVT operation, a fast locking phase-locked-loop (PLL) with initial random phase error reduction is proposed to continuously adjust the center frequency deviations of the SR oscillator (SRO) without interrupting the input data stream. Additionally, a concurrent quenching waveform (CQW) technique is devised to improve the SRO sensitivity and its noise performance. The proposed SRO architecture is controlled by two separate biasing branches to extend the sensitivity accumulation (SA) phase and reduce its noise during the SR phase, compared to the conventional optimal quenching waveform (OQW). The proposed SR receiver is implemented at 2.46 GHz center frequency in 180 nm SMIC CMOS technology and achieves better sensitivity, power consumption, noise performance, and PVT immunity compared with existent SR receiver architectures.

scholarly journals Polarimetric imaging mode of VLT/SPHERE/IRDIS

2020 ◽  
Vol 633 ◽  
pp. A63 ◽  
Author(s):  
J. de Boer ◽  
M. Langlois ◽  
R. G. van Holstein ◽  
J. H. Girard ◽  
D. Mouillet ◽  
...  
Keyword(s):  
Linear Polarization ◽  
Data Reduction ◽  
Correction Method ◽  
High Contrast ◽  
Polarization Effects ◽  
Instrumental Polarization ◽  
Polarimetric Imaging ◽  
Imaging Mode ◽  
Instrument Configuration

Context. Polarimetric imaging is one of the most effective techniques for high-contrast imaging and for the characterization of protoplanetary disks, and it has the potential of becoming instrumental in the characterization of exoplanets. The Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument installed on the Very Large Telescope (VLT) contains the InfraRed Dual-band Imager and Spectrograph (IRDIS) with a dual-beam polarimetric imaging (DPI) mode, which offers the capability of obtaining linear polarization images at high contrast and resolution. Aims. We aim to provide an overview of the polarimetric imaging mode of VLT/SPHERE/IRDIS and study its optical design to improve observing strategies and data reduction. Methods. For H-band observations of TW Hydrae, we compared two data reduction methods that correct for instrumental polarization effects in different ways: a minimization of the “noise” image (Uϕ), and a correction method based on a polarimetric model that we have developed, as presented in Paper II of this study. Results. We use observations of TW Hydrae to illustrate the data reduction. In the images of the protoplanetary disk around this star, we detect variability in the polarized intensity and angle of linear polarization that depend on the pointing-dependent instrument configuration. We explain these variations as instrumental polarization effects and correct for these effects using our model-based correction method. Conclusions. The polarimetric imaging mode of IRDIS has proven to be a very successful and productive high-contrast polarimetric imaging system. However, the instrument performance is strongly dependent on the specific instrument configuration. We suggest adjustments to future observing strategies to optimize polarimetric efficiency in field-tracking mode by avoiding unfavorable derotator angles. We recommend reducing on-sky data with the pipeline called IRDAP, which includes the model-based correction method (described in Paper II) to optimally account for the remaining telescope and instrumental polarization effects and to retrieve the true polarization state of the incident light.

The Blue Light Defects Activation in A-Si:H Pin Photodiode as a Biosensor

2020 ◽  
Vol 843 ◽  
pp. 64-69 ◽  
Author(s):  
Vera Gradišnik ◽  
Darko Gumbarević
Keyword(s):  
Energy Distribution ◽  
Blue Light ◽  
Energy Gap ◽  
Point Of Care ◽  
High Sensitivity ◽  
Cmos Technology ◽  
State Density ◽  
Low Noise ◽  
Defect States ◽  
Lab On Chip

The microfluidic Lab-On-Chip (LOC) systems, based on the CMOS technology, today grow rapidly based on requirement of the Point-of-care-testing (POCT). It is a need for a high sensitive biotransducers, as a part of biosensors to be integrated on LOC system. To detect low-level of light emitted by an analyte, promising material and devices are a p-i-n a-Si:H photodiodes. The observed absorbance of blue light in human cells HeLa (cervical carcinoma) induct H2O2 in same cells and consequently, chemical reaction with NO, detected as chemiluminescence signal by the photodiode, as well as formation of cytotoxic singlet oxygen. On the other side a-Si:H p-i-n photodiode has a high sensitivity on blue light at low-light intensity, good spectral responsivity and small reflectance for blue light, low dark current, low-noise in the range of low reverse bias voltages. The photoconductivity of a-Si:H p-i-n photodiode is influenced by the native and light induced localized state density and their energy distribution in the energy gap of intrinsic a-Si:H. It is observed that the defect states of i-layer at various bias voltages contribute to the detection of HeLa cells chemiluminescence. The optical bias dependence of modulated photocurrent method (OBMPC) using the blue LED light is applied to clarify the energy gap density of state nature and energy distribution, respectively in a-Si:H p-i-n photodiode i-layer.

scholarly journals Layered CMOS SPADs for Low Noise Detection of Charged Particles

2021 ◽  
Vol 8 ◽  
Author(s):  
Lodovico Ratti ◽  
Paolo Brogi ◽  
Gianmaria Collazuol ◽  
Gian-Franco Dalla Betta ◽  
Pier Simone Marrocchesi ◽  
...  
Keyword(s):  
Layer Structure ◽  
Charged Particles ◽  
Single Layer ◽  
Cmos Technology ◽  
Low Noise ◽  
Dark Count ◽  
Face To Face ◽  
Layer Structures ◽  
Beneficial Impact

This paper reports the characterization of SPAD arrays fabricated in a 150 nm CMOS technology in view of applications to the detection of charged particles. The test vehicle contains SPADs with different active area and operated with different quenching techniques, either passive or active. The set of devices under test (DUTs) consists of single-tier chips, about 30 mm2 in area, with dual-tier structures where two chips are face-to-face bump bonded to each other. In the dual-layer structure obtained in this way, the coincidence signal between overlapping SPAD pairs is read out, with a beneficial impact on the dark count noise performance. The DUT characterization was mainly focused on studying the breakdown voltage in the single-layer arrays and the dark count rate (DCR), measured in different working conditions, in both the single- and the dual-layer structures. Comparison between the DCR performance of the two configurations clearly emphasizes the advantage of the coincidence readout architecture.

Characterization of a Microfabricated Differential Scanning Calorimeter

2015 ◽  
Author(s):  
Shuyu Wang ◽  
Shifeng Yu ◽  
Lei Zuo
Keyword(s):  
Differential Scanning Calorimeter ◽  
High Performance ◽  
Drug Stability ◽  
High Sensitivity ◽  
Sample Volume ◽  
Small Time ◽  
Low Noise ◽  
Noise Equivalent Temperature Difference ◽  
Parallel Measurement

Calorimeters are critical tools for structural based drug design and drug stability assessment. Current pharmaceutical industry is seeking for high throughput calorimeters to reduce the research time and expenditure. MEMS-based calorimeter is a potential solution for it, since they are miniaturized to detect the enthalpy change during macro molecular interaction with smaller amount of samples, shorter time and could easily enable parallel measurement. Consequently, we present a Differential Scanning Calorimeter (DSC) that requires 2μL sample volume. It has high thermal insulation (1210μW/K), small time constant (6.95s) and high sensitivity (7.5V/W). The low noise equivalent temperature difference (NETD) could lead to 130nW of power resolution. These characterization results indicate the device could be potentially applied for macromolecular interaction application and increase the throughput with high performance.

Ultrastructural identification of three types of sensory setae on copepod antennae

1995 ◽  
Vol 53 ◽  
pp. 956-957
Author(s):  
T. M. Weatherby ◽  
P.H. Lenz
Keyword(s):  
Phase Locking ◽  
Membrane Surface ◽  
Reaction Times ◽  
High Sensitivity ◽  
Structural Features ◽  
Calanoid Copepods ◽  
Marine Food Webs ◽  
Dendritic Membrane ◽  
Ultrastructural Characterization

Crustaceans, as well as other arthropods, are covered with sensory setae and hairs, including mechanoand chemosensory sensillae with a ciliary origin. Calanoid copepods are small planktonic crustaceans forming a major link in marine food webs. In conjunction with behavioral and physiological studies of the antennae of calanoids, we undertook the ultrastructural characterization of sensory setae on the antennae of Pleuromamma xiphias.Distal mechanoreceptive setae exhibit exceptional behavioral and physiological performance characteristics: high sensitivity (<10 nm displacements), fast reaction times (<1 msec latency) and phase locking to high frequencies (1-2 kHz). Unusual structural features of the mechanoreceptors are likely to be related to their physiological sensitivity. These features include a large number (up to 3000) of microtubules in each sensory cell dendrite, arising from or anchored to electron dense rods associated with the ciliary basal body microtubule doublets. The microtubules are arranged in a regular array, with bridges between and within rows. These bundles of microtubules extend far into each mechanoreceptive seta and terminate in a staggered fashion along the dendritic membrane, contacting a large membrane surface area and providing a large potential site of mechanotransduction.

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