{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T16:47:22Z","timestamp":1778258842748,"version":"3.51.4"},"reference-count":16,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2019,1,5]],"date-time":"2019-01-05T00:00:00Z","timestamp":1546646400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>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 \u221217 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.<\/jats:p>","DOI":"10.3390\/s19010175","type":"journal-article","created":{"date-parts":[[2019,1,9]],"date-time":"2019-01-09T03:06:06Z","timestamp":1547003166000},"page":"175","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":29,"title":["An Improved Method for the Position Detection of a Quadrant Detector for Free Space Optical Communication"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4364-1257","authenticated-orcid":false,"given":"Qing","family":"Li","sequence":"first","affiliation":[{"name":"Institute of Optics and Electronics, Chinese Academy of Sciences, No. 1 Guangdian Road, Chengdu 610209, China"},{"name":"School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, No. 4 Section 2 North Jianshe Road, Chengdu 610054, China"},{"name":"Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Shaoxiong","family":"Xu","sequence":"additional","affiliation":[{"name":"Institute of Optics and Electronics, Chinese Academy of Sciences, No. 1 Guangdian Road, Chengdu 610209, China"},{"name":"Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7973-1695","authenticated-orcid":false,"given":"Jiawei","family":"Yu","sequence":"additional","affiliation":[{"name":"Institute of Optics and Electronics, Chinese Academy of Sciences, No. 1 Guangdian Road, Chengdu 610209, China"},{"name":"Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8179-9234","authenticated-orcid":false,"given":"Lingjie","family":"Yan","sequence":"additional","affiliation":[{"name":"Institute of Optics and Electronics, Chinese Academy of Sciences, No. 1 Guangdian Road, Chengdu 610209, China"},{"name":"Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100049, China"}]},{"given":"Yongmei","family":"Huang","sequence":"additional","affiliation":[{"name":"Institute of Optics and Electronics, Chinese Academy of Sciences, No. 1 Guangdian Road, Chengdu 610209, China"},{"name":"Key Laboratory of Optical Engineering, Chinese Academy of Sciences, Chengdu 610209, China"}]}],"member":"1968","published-online":{"date-parts":[[2019,1,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1217002","DOI":"10.3788\/CJL201542.1217002","article-title":"Study on main factors affecting position detection accuracy of four-quadrant detector","volume":"42","author":"Zhang","year":"2015","journal-title":"Chin. J. Laser"},{"key":"ref_2","unstructured":"Wu, J., Zhao, B., and Wu, Z. (2015, January 16\u201318). Improved measurement accuracy of the spot position on an InGaAs quadrant detector by introducing Boltzmann function. Proceedings of the 2015 International Conference on Optoelectronics and Microelectronics (ICOM), Changchun, China."},{"key":"ref_3","unstructured":"Gao, Z. (2014). Study on Vibration Characteristics Measurement Technology of Airborne Photoelectric Platform. [Ph.D. Thesis, Dalian Maritime University]."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"081102","DOI":"10.1063\/1.3326078","article-title":"Improved measurement accuracy of the quadrant detector through improvement of linearity index","volume":"96","author":"Cui","year":"2010","journal-title":"Appl. Phys. Lett."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1692","DOI":"10.1364\/OL.36.001692","article-title":"Analysis and improvement of laguerre gaussian beam position estimation using quadrant detectors","volume":"36","author":"Cui","year":"2011","journal-title":"Opt. Lett."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"6806","DOI":"10.1016\/j.ijleo.2013.06.010","article-title":"Investigation of positioning algorithm and method for increasing the linear measurement range for four-quadrant detector","volume":"124","author":"Chen","year":"2013","journal-title":"Optik"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"5525","DOI":"10.1088\/0957-4484\/17\/21\/038","article-title":"Robust approach to maximize the range and accuracy of force application in atomic force microscopes with nonlinear position-sensitive detectors","volume":"17","author":"Silva","year":"2006","journal-title":"Nanotechnology"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1364\/OL.36.000409","article-title":"Quadrant detector calibration for vortex beams","volume":"36","author":"Hermosa","year":"2011","journal-title":"Opt. Lett."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"024703","DOI":"10.1063\/1.1854196","article-title":"A low-cost, high-performance, digital signal processor-based lock-in amplifier capable of measuring multiple frequency sweeps simultaneously","volume":"76","author":"Sonnaillon","year":"2005","journal-title":"Rev. Sci. Instrum."},{"key":"ref_10","unstructured":"Chen, L. (2010). Research on the Precise Detection Technology of Infrared Laser Facula Position Based on QD. [Ph.D. Thesis, Changchun University of Science and Technology]."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1109\/TIM.2008.2005259","article-title":"Optimization of Optical Receiver Parameters for Pulsed Laser-tracking systems","volume":"58","author":"Manojlovic","year":"2009","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"064301","DOI":"10.1117\/1.2947581","article-title":"Acousto-optic tracking system for free space optical communications","volume":"47","author":"Nikulin","year":"2008","journal-title":"Opt. Eng."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1013","DOI":"10.1016\/S0016-0032(99)00021-6","article-title":"Probability distributions of the envelope and phase, and their derivatives in time of the sum of a non_stationary sine signal and narrow-band Gaussian noise","volume":"336","author":"Shmaliy","year":"1999","journal-title":"J. Frankl. Inst."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1465","DOI":"10.1016\/S0165-1684(01)00033-0","article-title":"Windowed discrete cosine and sine transforms for shifting data","volume":"81","author":"Sherlock","year":"2001","journal-title":"Signal Process."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1668","DOI":"10.1109\/16.231576","article-title":"Position dependence of the transient response of a position sensitive detector under Periodic pulsed light modulation","volume":"40","author":"Narayanan","year":"1993","journal-title":"IEEE Trans. Electron Devices"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"74190Z","DOI":"10.1117\/12.825520","article-title":"Quadrant photodiode for electronic processing","volume":"7419","author":"Sanchez","year":"2009","journal-title":"Proc. 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