Study on Main Factors Affecting Position Detection Accuracy of Four-Quadrant Detector

Hui, 张辉 Zhang; Yunshan, 陈云善 Chen; Tianwen, 耿天文 Geng; Jiabin, 吴佳彬 Wu; Tao, 陈涛 Chen

doi:10.3788/cjl201542.1217002

Cited by 10 publications

(10 citation statements)

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“…The QD has an active radius of 1 mm with a gap width of 0.01 mm and was mounted on a three-dimensional micro-displacement motion stage. We used a Gaussian beam with a spot diameter of 0.51 mm to improve the detection accuracy [6].…”

Section: Methodsmentioning

confidence: 99%

“…Many methods have been presented to improve the detection accuracy for a single spot on the QD. Zhang et al [6] proposed that the detection accuracy of QD was related to spot radius, spot position and output SNR. Jiabin et al [7] analyzed the nonlinear characteristic of QD and proposed a linear correction method based on Boltzmann function.…”

Section: Introductionmentioning

confidence: 99%

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Method to Measure Light Spot Position in Beacon-Less Inter-Satellite Communication System

et al. 2019

Applied Sciences

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This article focuses on a beacon-less Inter-satellite optical wireless communication (Is-OWC) system. This system uses the same wavelength for the transmitted and received laser beams and uses part of communication light beam as beacon light instead of an additional high divergent beacon laser. Thus, a part of transmitted light will be reflected in optical path and leaked into acquisition, tracking and targeting (ATP) subsystem. This reflected light will seriously interfere with the spot position measurement of received light. To solve this problem, we propose a new method based on intensity modulation and cyclic cross-correlation (CCR). Experiment results show that even when the reflected and received beams differ in intensity by 91.7 times, we can still accurately detect the received light spot position by using the proposed method, where the maximum error is 0.026 mrad and the root mean square error is as low as 0.012 mrad.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Method to Measure Light Spot Position in Beacon-Less Inter-Satellite Communication System

et al. 2019

Applied Sciences

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“…It can be seen from Equations (1) and (2) that using QD to detect the spot position essentially calculates the distribution ratio of the light beam energy irradiated to the four APDs. Furthermore, literature [ 20 ] proposed that the spot position detection accuracy is affected by the factors such as spot position, spot radius and SNR. Therefore, it is necessary to find a way to effectively improve the output SNR of QD according to the characteristics of the noise distribution.…”

Section: The Performance Of the No Independent Beacon Light Atp Symentioning

confidence: 99%

TRC-Based High-Precision Spot Position Detection in Inter-Satellite Laser Communication

Guo

et al. 2020

Sensors

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Inter-satellite laser communication (Is-OWC) is one of the main space optical communication technologies currently studied in various countries. In recent years, a kind of Is-OWC communication terminal without independent beacon light has appeared. Such terminals do not have a separate beacon laser with a large divergence angle, but use a narrower communication beam to complete space capture and tracking. Therefore, the energy of the light beam divided by the acquisition, tracking, and aiming (ATP) system is greatly reduced. How to perform high-precision spot position detection under extremely low signal-to-noise ratio (SNR) is a problem that must be faced. Aiming to resolve this problem, this article proposes to use a cosine signal to modulate the intensity of the signal light, so as to convert the problem of detecting a weak light signal into the problem of detecting a line spectrum signal. The authors used the time reversal convolution (TRC) algorithm with a window function to suppress noise and enhance the spectrum line, so as to accurately detect the amplitudes of the weak photocurrents. Finally, by calculating the ratio of the photocurrent amplitude values, the precise spot position is obtained. In the experiment, when the output SNR of the four-quadrant detector (QD) is as low as −17.86 dB, the proposed method can still detect the spot position and the absolute error is limited within 0.0238 mrad.

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“…It is necessary to study how to improve the detection accuracy of a QD. Zhang et al [1] proposed that the detection accuracy of a QD was related to the spot radius, spot position, and the QD output signal-to-noise ratio (SNR). Wu et al [2] analyzed the nonlinear characteristic of a QD and proposed a linear correction method based on Boltzmann function.…”

Section: Introductionmentioning

confidence: 99%

An Improved Method for the Position Detection of a Quadrant Detector for Free Space Optical Communication

et al. 2019

Sensors

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In free space optical communication, a beacon light loses too much energy after a long-distance transmission and faces strong interference from background light. The beacon light illuminated on a quadrant detector (QD) is so weak that the output signal-to-noise ratio (SNR) of a QD is very low, which leads to a significant decrease in the accuracy of the direct position detection method. To solve this problem, an improved light spot position detecting method is proposed. Since the background light and the dark current noise are white noise, we could consider concentrating the energy of QD output signal at a certain frequency point to enhance the output SNR. Therefore, a cosine signal is used to modulate the intensity of a beacon light at the transmitting end. Then the QD output photocurrents are also cosine signals with the same frequency as the modulating signal. Putting the photocurrent signals into a cross-correlation operation with a reference signal, which is the same as the modulating signal, can enhance the QD output SNR at a certain frequency point. Unfortunately, the result of the classical cross-correlation is attenuated with increasing delay. It is hard to detect the amplitude of the classical cross-correlation result. So, we used cyclic cross-correlation to obtain a stable correlation result to detect its amplitude accurately. The experiment results show that even when the QD output SNR is less than −17 dB, the detection root-mean-square error of the proposed method is 0.0092 mm, which is a quarter of the direct position detection method. Moreover, this method only needs a small amount of data to accomplish the calculation and is especially suitable for real-time spot position detection.

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Study on Main Factors Affecting Position Detection Accuracy of Four-Quadrant Detector

Cited by 10 publications

References 0 publications

Method to Measure Light Spot Position in Beacon-Less Inter-Satellite Communication System

Method to Measure Light Spot Position in Beacon-Less Inter-Satellite Communication System

TRC-Based High-Precision Spot Position Detection in Inter-Satellite Laser Communication

An Improved Method for the Position Detection of a Quadrant Detector for Free Space Optical Communication

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