摘要
为实现海水吸光度大范围长时间的测量,设计了适用于海洋拖曳观测系统的原位吸光度传感器。传感器可实现多波段吸光度同步探测,选取LED和光电二极管分别作为光源和探测器,通过多通道并排排列的光机结构布局方式及高集成电路优化等实现传感器的小型化及低功耗设计;使用窄带光学滤光片及数字锁相处理算法实现明场环境下的海水吸光度原位探测。实验证明该吸光度传感器具有高精度、小体积、抗环境干扰能力强、功耗低、稳定等优点,传感器精度优于0.0001 AU。该吸光度传感器可通过设计不同路径长度的吸收池来适应复杂的水域环境,也可在近岸海域搭载船只通过走航式实现连续探测,具有广泛的应用前景。
Absorbance is an important parameter to describe the optical properties of sea water,it can directly reflect the transparency of sea water and the degree of light attenuation of sea water,it is one of the inherent optical properties of water.The results of absorbance of sea water have an important guiding effect on the field of underwater optical communication and spectral detection.Too little spectral information can be obtained by the existing absorbance measurement equipment,hyperspectral absorbance measurement equipment has problems such as expensive price and large volume,so it is not suitable for large range of in situ absorbance detection.In order to achieve a wide range of long-term measurement of sea water absorbance,an in-situ absorbance sensor suitable for ocean towed observation systems is designed.The sensor can realize the synchronous detection of multi-band absorbance,select LED as a light source of the sensor,and select photodiode as detector respectively of the sensor,the optical path of the sensor absorption cell is 10 mm.The transmission optical path structure design is adopted,the multi band LED is located at the transmitter end of the sensor,and the detector is located at the receiving end of the sensor.And realize the miniaturization and low-power consumption design of the sensor through the multi-channel side-by-side arrangement of the photomechanical structure layout and highly integrated circuit optimization.The sensor selected 8 LED light sources of relatively important feature bands at 340~980 nm for absorbance measurement.The 8-channel LEDs at the transmitting end are modulated with 781.25 Hz sine wave signals,after the beam is collimated,it is attenuated through the absorption cell,and then converged to the photodetector at the receiving end.After receiving the signal,the photodetector demodulates and analyzes the signal using a digital phase-locked algorithm based on the cross-correlation detection principle to achieve absorbance measurement.From the optical perspective,the reference detector was placed near the LED light source to calibrate the influence of light source fluctuation on the absorbance result.The sensor used a narrow-band filter with a high cut-off depth to filter out stray light outside the band at the receiving end.At the same time,it can avoid the influence of scattered light from adjacent channels.From the circuit point of view,the signal received by the detector is realized by a digital phase locking algorithm.The narrow-band optical filter and digital phase-locked processing algorithm at the receiving end can effectively suppress the influence of background stray-light and signal interference noise,and realize in situ detection of seawater absorbance in the open field environment,which is the key to achieve high precision absorbance measurement.The laboratory precision test and the comparison test with the same type of equipment and the South China Sea test prove that the absorbance sensor has the advantages of high precision,small volume,strong anti-environmental interference ability,low power consumption and stability,and the precision of the sensor is better than 0.0001 AU(Absorbance Unit).In addition,the absorbance sensor uses photodiode as the detector to make the whole system have a fast response speed,which can capture the rapid change of the absorbance of the marine environment,the absorbance sensor can achieve different detection requirements by replacing the light source of other bands and the corresponding filter.During the use of the sensor,temperature and salinity sensors are also used to adjust the temperature and salinity of the absorbance results,so as to obtain more accurate measurement data.The absorbance sensor can also adapt to the complex water environment by designing circulation cell of different path lengths.It can also carry ships in coastal waters to achieve continuous detection by sailing,which has a wide range of application prospects.
作者
薛庆生
郝锡杰
王福鹏
XUE Qingsheng;HAO Xijie;WANG Fupeng(School of Physics and Optoelectronic Engineering,Department of Information Science and Engineering,Ocean University of China,Qingdao 266100,China)
出处
《光子学报》
EI
CAS
CSCD
北大核心
2023年第4期95-105,共11页
Acta Photonica Sinica
基金
国家自然科学基金(Nos.U2006209,41575023)
山东省重点研发计划项目(No.2020CXGC010706)
泰山学者科研经费(No.202105033008)
人才计划项目(No.202112003)
中国科学院海洋大科学研究中心重点部署项目(No.COMS2019J04)
中国工程院咨询研究项目(No.2020‒XZ‒5)。
关键词
吸光度传感器
高精度
原位探测
拖曳观测
数字锁相
Absorbance sensors
High precision
In situ detection
Towing observation
Digital phase locking
