A high-resolution fiber turbidity sensor has been developed to measure the wide dynamic range of turbidity. To improve the accuracy of measurements, the high sensitive single-photon detection technique is adopted in the sensor by using an avalanche photodiode (APD) to detect the total intensity of transmitted light and quantize it to the corresponding number of photons. A theoretical model for turbidity measurement is proposed by combining the B-L transmission law with the single photon counting theory. In order to cover a wide dynamic range measurement based on only one measurement system, an optimal optical power for the sensor must be chosen. Therefore, an experiment is designed to measures the different turbidity solutions by gradually changing the power of incident light. The test results show that, with the increasement of light intensity, the measured data fit better with the theoretical one when the measured turbidity is lower than 0.1NTU. However, the light intensity cannot be increased without limit in high turbidity region, especially when the turbidity is high than 1NTU, since there is a corresponding upper limit for the detection of avalanche photodiode (APD). After the processing and analysis of test data, the test results indicated the sensor can obtain the best measurement accuracy when the optical power of incident light at 11mW. The measured turbidity range is as wide as 50dB from 0.01 to 1000NTU. The proposed fiber sensor is robust and can be used for the wide dynamic turbidity detection for drinking water or some remote monitoring of water pollution.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.