Light path structure and method for detecting large-dynamic range liquid turbidity

The invention discloses a light path structure and a method for detecting large-dynamic range liquid turbidity. In the light path structure, an infrared emission light path, a first scattered light path, a second scattered light path, a long vessel transmission light path and a short vessel transmission light path are arranged in a groove-shaped concave cavity respectively; after being subjected to beam expanding by a convex lens in the front, light emitted from a detecting light source is transmitted in liquid in the concave cavity and is received by light detectors respectively, and an electrical signal outputted by each light detector is inputted to an amplification demodulator circuit to be converted into a direct-current voltage signal for calculating liquid turbidity; and the detecting light source realizes pulse modulation by the demodulator circuit. By the structure and the method, the requirement of the accurate detection of the turbidity of various water bodies with different concentrations is met fully, so the structure can be used for detecting water turbidity quickly on line by environmental monitoring departments and also can be used for performing long-term continuous detection on the water turbidity of fixed monitoring points by being arranged on a buoy or an automatic monitoring station, and has the excellent market prospect.