Pair Of Photodiodes Research Articles

Celestial compass sensor mimics the insect eye for navigation under cloudy and occluded skies

Insects use the sun’s position (even when concealed) as a compass for navigation by filtering celestial light intensity and polarisation through their compound eyes. To replicate this functionality, we present a sensor that imitates essential aspects of insect eyes, particularly the fan-like arrangement of polarised light receptors in their dorsal rim area. Our sensor comprises a ring of eight pairs of photodiodes (evaluating two orthogonal orientations of polarised light) to analyse the skylight coming from different directions. Because the layout of our sensor aligns with the polarised light pattern in the sky, a circular-mean model that integrates information spatially across the analysers can estimate the solar azimuth. When using the same sensor design, our model achieves lower compass errors than alternative (and computationally more complex) algorithms, especially under cloudy and occluded skies. Thus, the morphology and processing of the insect celestial compass provide an efficient and robust directional input for navigation.

Self-Powered Gate Drive Circuits With Optical Signal Isolation for In-Vehicle Marx Circuit of Ozonizer

Reducing the cost of a Marx circuit as a high-voltage power supply for nitrogen oxide (NOx) decomposition for diesel vehicles is required. The Marx circuit with MOSFETs has an advantage in size compared to the Marx circuit with gap switches. However, the Marx circuit with MOSFETs needs gate drive circuits on the gate of each MOSFET. The gate signal and drive power must be supplied to each gate with isolation in a low-cost way. However, the transformer for the isolation with high withstand voltage, such as 10 kV or more, is typically high cost because of the low demand. This article proposes the self-powered gate drive circuit using the charging path of the Marx circuit. The proposed gate drive circuit only requires a low withstand voltage because the power for the MOSFET on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n$ </tex-math></inline-formula> th stage is supplied from the ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n -1$ </tex-math></inline-formula> )th stage via a low-voltage transformer. Besides, the gate signal is transmitted through pairs of LEDs and photodiodes instead of high-cost optical fibers. The proposed gate drive circuits are developed and implemented into a prototype of the Marx circuit with an output voltage of 4 kV. From the experiments, it is demonstrated that the proposed drive circuits provide both drive power and gate signal.

Design of a Falling Ball Speed Measuring Instrument in Viscosity Experiment Using Arduino UNO ATmega

Viscosity experiments in universities generally use falling ball method with manual observations. Measuring travel time of iron ball from one point to another manually using a stopwatch can cause a large error. This problem can be solved by designing a digital falling ball viscometer using infrared and photodiode configured with Arduino. Infrared and photodiode pairs are placed in the top and bottom glass tubes to detect the movement of iron ball so that it produces a change in voltage. This voltage change is used to mark start and stop times in time measurement. The time measurement obtained is then used to calculate speed of the ball through the formula for distance between sensors divided by time. Data obtained is then entered into viscosity formula of falling ball method to obtain viscosity value of fluid (oil). The digital falling ball viscometer is accurate when error obtained is less than 5%. The results obtained are the error of the digital viscometer measurement results are better than the error of the manual viscometer. The highest error obtained from the digital viscometer is 4%, while the lowest is 1%. This indicates that the digital falling ball viscometer has a high enough accuracy so that data obtained is in accordance with the reference and can be used as a viscosity experiment tool using falling ball method.

Optical Sensor System for Chemical Flow Rate Monitoring with Direct Nozzle Injection

HighlightsA novel optical sensor system was developed to accurately measure simulated chemical (water with dye) flow rates observed with direct nozzle injection systems for agricultural sprayers.The average error in chemical flow rate estimates was only 2% across a typical range of injection rates.The prototype optical sensor system was capable of detecting dye dilutions to a level of 1:150,000.Abstract. Direct injection systems have the potential to provide several benefits to spray applicators (e.g., easing boom cleanout procedures); however, lag time and proper mixing continue to hinder adoption. Development efforts have typically focused on moving the chemical injection point closer to the nozzle to improve the application rate response. This poses an important challenge for proper metering of the chemical, i.e., accurate measurement of extremely low chemical flow rates. In this study, an optical sensor system was integrated with a typical carrier flowmeter and calibration methodology to measure chemical flow rates for a direct nozzle injection sprayer. The optical sensor used a light-emitting diode (LED) and photodiode pair to measure the absorbance of a dye mixed with a simulated chemical solution. Laboratory tests were conducted to evaluate the measurement accuracy of the system in which sensor output was compared directly to measurements from a spectrophotometer. Results indicated that the calibrated sensor system was able to estimate the simulated chemical flow rate with an average error of 2%. The sensor system was also capable of accurate measurements as the initial concentrations of dye mixed with the chemical solution varied. Keywords: Application equipment, Pesticides, Sprayers, Spraying equipment.

Acousto-optic Light Pulse Shaper for Measuring the Parameters of Photo-detectors

The paper emphasizes that intensive utilization of the optical range increases the need for the development of new optoelectronic devices. Accordingly, there is a growth in the need for effective methods and tools to study photoelectric properties of semiconductor materials, including photo-detectors.In the paper we have analyzed the well-known methods and tools for measuring the photo-detector parameters, defined the restrictions in their applications, and proved that it is relevant to create a measuring system, the parameters of which are easily adapted to the study of photoelectric characteristics of a wide range of semiconductor materials, including photo-detectors.The scheme and principle of operation of the acousto-optic processor and the features of the photo-elastic effect are discussed, and it is proved that they can be used to form a light pulse of required duration and power. The expressions obtained for calculating the response at the acousto-optic processor output enable us to estimate separately the effects of time of crossing the optical beam by the elastic wave packet and the photo-detector inertia.The capability to determine the time of crossing the optical beam by the elastic wave packet and taking it into account as a device error has been substantiated. The proposed formulas have been tested and by numerical analysis based on the datasheet specifications of the FD-24K photodiode, the effectiveness of the obtained expressions has been convincingly proven.The inertia parameters of a particular sample of the FD-24K photodiode are experimentally studied. The emphasis is upon measuring the rise time of the transient response of the object under study. The exact rise time value of the transient response of the experimental FD-24K sample was approximately 7 μs, which is less than that indicated (≤10 μs) in the product certificate. In real life, such a measurement is necessary when selecting the photodiode pairs with identical parameters.By comparing the results of numerical analysis and experimental studies, it has been convincingly proven that the features of the photo-elastic effect can be used to construct a light pulse shaper with the required parameters.

Low frequency noise in P-InAsSbP/n-InAs infrared light emitting diode-photodiode pairs

Low frequency noise in P-InAsSbP/n-InAs infrared light emitting diode- photodiode pairs is investigated for the first time at 300 K. It is shown that photocurrent fluctuations under LED illumination are smaller than photocurrent fluctuations under a black body illumination. When the photodiode is illuminated by LED, the spectral noise density follows the 1/f dependence. In the case of a black body illumination we observe a significant contribution of generation-recombination noise.

Spectrally filtered photodiode pairs for on-chip ratiometric aptasensing of cytokine dynamics

Miniaturized, cost-effective cytokine sensing devices are essential for health monitoring and critical care of patients with acute immune responses. Here we report an on-chip ratiometric aptasensing device to monitor the dynamics of an essential immune response biomarker, interferon-gamma. Our device is formed by pairs of spectrally filtered silicon photodiodes that are surface functionalized with aptamer probes. These photodiode pairs are able to rapidly detect two-color fluorescence changes transduced from aptamer-cytokine binding events within c.a. 6 min at picomolar levels, which are sufficient to capture the cytokine transients in point-of-care settings. Furthermore, our device can be reset to baseline by simple washing steps, yielding consistent readout in consecutive runs. Combined with their chip-scale construct and real-time operation, our cytokine sensors may have possible use in point-of-care and therapeutic screening applications.

Personalized Low-Energy Defibrillation Through Feedback Based Resynchronization Therapy.

Defibrillation shocks may cause AV node burnout, scar formation, and pain. In this study, we present a real-time feedback-based control of ventricular fibrillation (VF) with a series of low-energy shocks using ventricular electrical activity as the feedback input. Isolated rabbit hearts were Langendorff perfused and stained with a fluorescent Vm dye. The ventricular activity was measured with a pair of photodiodes, and processed with a feedback controller to calculate defibrillation shock parameters in real-time. Shock timing was based on desynchronized activation of the left and right ventricles during VF, and the strength was proportional to the amplitude difference of the photodiode signals. Shocks were delivered with a custom-developed arbitrary waveform trans-conductance amplifier. Feedback based resynchronization therapy converts VT to MT before sinus rhythm is restored with a reduction of defibrillation energy, compared to a single biphasic shock. Feedback based resynchronization therapy is based on real-time sensing of ventricular activity, while a series of low-energy shocks are delivered, reducing the risk of associated side effects.

Polarization Multiplexed Optical OFDM System With a Beat Interference Cancellation Receiver

A novel beat interference cancellation receiver (BICR) is proposed to cancel the signal-signal beat interference (SSBI) for polarization division multiplexed (PDM) optical orthogonal frequency division multiplexing (OOFDM) system, where two single sideband (SSB) OOFDM signals are polarization multiplexed along with their offset optical carriers (OCs) located at opposite sides. At receiver, the PDM SSB-OOFDM signal is equally power split into four beams with one or two OCs filtered out, and then fed into two balanced photodiode pairs for recovering the RF-OFDM signals with SSBI cancellation. The PDM SSB-OOFDM system is insensitive to fiber polarization mode dispersion since the proposed BICR is implemented without polarization-sensitive devices. Moreover, the spectral efficiency is greatly improved because of PDM and the small guard band since the SSBIs are eliminated. The proposed BICR scheme is validated with a simulation link of 112 Gbps 16-QAM PDM SSB-OOFDM signals. After 120km SSMF transmission, the EVM keeps below forward error correction limit of 16.3%.

Optical Sensor-Embedded Pneumatic Artificial Muscle for Position and Force Estimation.

This study presents the design of a pneumatic artificial muscle with integrated soft optical sensing for estimation of muscle contraction length and contraction force. Each optical sensor uses an light emitting diode (LED)-photodiode pair to measure the light reflected by a silicone diaphragm embedded in the muscle. One diaphragm is designed to respond primarily to changes in muscle pressure, whereas the other is designed to respond to changes in muscle length. Muscle sensors were calibrated by measuring muscle contraction force versus length for a range of fixed muscle pressures and then mapping optical sensor data to the corresponding length and force data. To evaluate sensorized muscle performance in a robotic system, two antagonistic muscle pairs were used to actuate a planar two-degree-of-freedom arm. In various static and dynamic tests, arm positions and forces were estimated from optical sensor measurements. Optical sensor estimates of static and dynamic end-effector position estimation yielded average errors of 1.3 and 1.1 cm, respectively. Optical sensor estimates of static and dynamic end-effector force yielded average total force errors of 0.16 and 0.12 N for maximum end-effector forces of 2.0 and 2.4 N, respectively.

Foundry-Enabled High-Power Photodetectors for Microwave Photonics

We report on arrayed germanium-on-silicon waveguide photodetectors for high-power analog applications utilizing the AIM Photonics silicon foundry. Photodetector arrays with two, four, and eight elements reach output powers of -0.4 dBm, 10 dBm, and 14.3 dBm at 18 GHz, 12 GHz, and 5 GHz, respectively. The 4-photodiode array has an output third order intercept point (OIP3) above 20 dBm up to 12 GHz and shows a 5-dB improvement over a single photodiode. An integrated 20 GHz receiver based on a pair of balanced photodiodes and a Mach-Zehnder delay line interferometer is successfully demonstrated in an optical phase-modulated link.

Differential single-pixel camera enabling low-cost microscopy in near-infrared spectral region.

The optical microscope for wavelengths above 1100 nm is a very important tool for characterizing the microstructure of a broad range of samples. The availability of the technique is, however, limited because special detectors with temperature stabilization, which are costly, must be used. We present the construction of a low-cost near-infrared microscope (800-1700 nm) based on the principles of compressed sensing. The presented setup is very simple and robust. It requires no temperature stabilization and can be used under standard laboratory conditions. We demonstrate that such a microscope, which uses a simple pair of balanced photodiodes as a detector, can acquire microscopic images of the sample that are comparable with those acquired by a standard microscope. Owing to its simplicity, the presented setup can provide access to infrared transmission microscopy and to a broad range of laboratories.

Wearable near-infrared optical probe for continuous monitoring during breast cancer neoadjuvant chemotherapy infusions.

We present a new continuous-wave wearable diffuse optical probe aimed at investigating the hemodynamic response of locally advanced breast cancer patients during neoadjuvant chemotherapy infusions. The system consists of a flexible printed circuit board that supports an array of six dual wavelength surface-mount LED and photodiode pairs. The probe is encased in a soft silicone housing that conforms to natural breast shape. Probe performance was evaluated using tissue-simulating phantoms and in vivo normal volunteer measurements. High SNR (71 dB), low source-detector crosstalk ( ? 60 ?? dB ), high measurement precision (0.17%), and good thermal stability (0.22% V rms / ° C ) were achieved in phantom studies. A cuff occlusion experiment was performed on the forearm of a healthy volunteer to demonstrate the ability to track rapid hemodynamic changes. Proof-of-principle normal volunteer measurements were taken to demonstrate the ability to collect continuous in vivo breast measurements. This wearable probe is a first of its kind tool to explore prognostic hemodynamic changes during chemotherapy in breast cancer patients.

Nozzle Sensor for In-System Chemical Concentration Monitoring

Abstract. Chemical concentration is a vital parameter for determining appropriate chemical application. This study describes the design and testing of a sensor that attempted to monitor concentration of chemicals upstream from each nozzle body. The sensor is based on an LED and photodiode pair. Its ability to detect chemical concentration within the main carrier was tested with a 2,4-D formulation, a glyphosate formulation, and a powdered Acid Blue 9 dye. The liquid herbicide formulations of glyphosate and 2,4-D were tested across common application concentrations of 0% to 12.5% by volume. The powdered dye produced a much stronger effect on the sensor and was only tested at the much lower concentrations of 0 to 50 mg L-1. Further tests were conducted in which the dye was mixed with the herbicide formulation before the combined solution was added to the carrier. While this enabled establishment of pre-determined sensor outputs based on given concentrations of the pre-mixed solution, the sensor may have been responding to the predominance of a dye mixed with a herbicide formulation and not directly to the concentration of the herbicide. While the sensor did not appreciably respond to the concentration of the glyphosate formulation, it did respond in a consistent manner to the 2,4-D formulation and the dye. The sensor‘s response to the concentration of these chemicals was a rational (1/x type) relationship, and the R2 values for the rational models describing these relationships were greater than 0.99. With the mixed dye and herbicide formulation, the effects of the dye and the 2,4-D formulation combined independently, and the total sensor output was a multiplication of the percent effect of each alone. The test with the pre-mixed dye and 2,4-D formulation produced the expected 1 V output at a 12.5% by volume concentration of the 2,4-D formulation, proving that dye can be added to a herbicide to produce a desired response from the sensor. Overall, the sensor‘s response was remarkably stable, with a maximum standard deviation of 42.2 mg L-1 of 2,4-D active ingredient for samples taken at a constant chemical concentration. These tests confirmed that the sensor could respond to chemical formulations and dye in a consistent and predictable manner. However, use of the sensor for herbicide monitoring will require sensor calibration for each combination of herbicide and dye mixture, as the light transmittance properties of the tested mixtures were not quantified and the light transmittance properties of formulations and dyes can be arbitrarily changed by manufacturers.

Colorless beat interference cancellation receiver for the orthogonally polarized SSB-OOFDM signal with reduced guard band.

In the paper, we have proposed a novel optical orthogonal frequency division multiplexing (OOFDM) link scheme with the colorless beat interference cancellation receiver (BICR) structure for the single-sideband OOFDM (SSB-OOFDM) signal with an orthogonally polarized optical carrier and sideband, which is generated by using a polarization modulator and an optical band-pass filter. The BICR, employing only a polarization beam splitter and a balanced photodiode pair, can colorlessly mitigate the signal-signal beat interference (SSBI) induced by the square-law detection in a photodiode and thus the spectral efficiency (SE) is improved by reducing the guard band (GB) between the optical carrier and OOFDM signal. A simulation link for the 40 Gbit/s 16-QAM SSB-OOFDM signal with a reduced GB is built to demonstrate the feasibility of our proposed scheme. The simulation results indicate that the link has a higher SE compared to the conventional intensity modulation and direction detection scheme and the BICR exhibits a better performance in suppressing SSBI according to the error vector magnitude and the constellation diagrams.

InGaAsP/InP integrated waveguide photodetector pair using quantum well intermixing

Quantum well intermixing using single layer ZrO2 capped annealing on InGaAsP/InP MQW has been used to achieve integrated two wavelength photodiode pair. The selective solubility of In and Ga in ZrO2 has been used for bandgap engineering. The top layers of the hetrostructure is chosen by lithography and etching into the same hetrostructure. The regions with lower desired bandgaps are chosen to be of lower Ga content. Comparison of different top layer and anneal conditions with respect to wavelength shift and surface quality is also shown. A uniform F ion implantation performed before the annealing has shown an increase of differential blue shift. Regions with up to a minimum of 60 nm InGaAs top layer have been shown to produce a differential bandgap change of 10 nm with no F ion implantation, and 30 nm with uniform F ion implantation (when annealed at 750 °C for 10 s with 300 nm ZrO2 cap).

Beam geometry, alignment, and wavefront aberration effects on interferometric differential wavefront sensing

Heterodyne interferometry is a widely accepted methodology with high resolution in many metrology applications. As a functionality enhancement, differential wavefront sensing (DWS) enables simultaneous measurement of displacement, pitch, and yaw using a displacement interferometry system and a single beam incident on a plane mirror target. The angular change is measured using a weighted phase average between symmetrically adjacent quadrant photodiode pairs. In this paper, we present an analytical model to predict the scaling of differential phase signals based on fundamental Gaussian beams. Several numerical models are presented to discuss the effects of physical beam parameters, detector size, system alignment errors, and beam wavefront aberrations on the DWS technique. The results of our modeling predict rotational scaling factors and a usable linear range. Furthermore, experimental results show the analytically predicted scaling factor is in good agreement with empirical calibration. Our three degree-of-freedom interferometer can achieve a resolution of 0.4 nm in displacement and 0.2 μrad in pitch and yaw simultaneously.

Smart photoplethysmographic sensor for pulse wave registration at different vascular depths.

The aim of this paper is to propose a smart optical sensor for cardiovascular activity monitoring at different tissue layers. Photoplethysmography (PPG) is a noninvasive optical technique for monitoring mainly blood volume changes in the examined tissue. However, different important physiological parameters, such as oxygen saturation, heart and breathing rate, dynamics of skin micro-circulation, vasomotion activity etc., can be extracted from the registered PPG signal. The developed sensor consists of 32 light emitting sources with four different wavelengths, which are located to the four different distances from four photo detectors. Compared to the existing sensors, the system enables to select the optimal LED (light emitting diode) and photo detector couple in order to obtain the pulse wave signal from the interested blood vessels with the highest possible signal to noise ratio. In this study, the designed PPG sensor was tested for the pulse wave registration from radial artery. The highest efficiency and signal to noise ratio was achieved using infrared LED (940 nm) and photo-diode pair.

Chemiluminescence detection in urethane-acrylate microfluidic devices

This work reports on the use of a urethane-acrylate (UA)-based resin in the construction of micro-flow injection analyzers (μFIA) with integrated chemiluminescence (CL) cells for application in ordinary analytical determinations. The proposed devices, manufactured by a rapid and low-cost prototyping procedure, offered suitable transparency to visible electromagnetic radiation and supported flow rates over 2.0mLmin−1 without leakages or damages to the structures of the CL cell. By using a pair of photodiodes as detectors, the determination of hypochlorite ions (2.0–20mgL−1) based on its reaction with 3-aminophthalhydrazide (luminol) provided a linear response (R2=0.998) with a limit of detection (LOD) of 0.5mgL−1 and repeatability of 0.4% for successive injections (n=4) of a 2.0mgL−1 standard solution. The determination of nitrite ions (10–80μgL−1), carried out using a photomultiplier to detect the quenching of luminescence for the hypochlorite (ClO−)/luminol reaction in the presence of the analyte, demonstrated an adequate linearity (R2=0.998), LOD of 5.0μgL−1 and precision of 0.6% for successive injections (n=4) of a 10μgL−1 solution. The results obtained for the determination of hypochlorite in household bleaches and of nitrite in commercial pâtés did not differ significantly from the reference methods at a confidence level of 95%, demonstrating a suitable accuracy for the miniaturized methods. In addition, only 24mL of residues were produced per hour in both procedures, so that the proposed analyzer fits one of the green chemistry requirements.

Time-multiplexed measurements of nonclassical light at telecom wavelengths

We report the experimental reconstruction of the statistical properties of an ultrafast pulsed type-II parametric down conversion source in a periodically poled KTP waveguide at telecom wavelengths, with almost perfect photon-number correlations. We used a photon-number-resolving time-multiplexed detector based on a fiber-optical setup and a pair of avalanche photodiodes. By resorting to a germane data-pattern tomography, we assess the properties of the nonclassical light states states with unprecedented precision.