The invention provides a near-
infrared moisture meter based on three LED lamps, which is characterized in that a
photodiode detector is positioned at the focus of a plano-concave focusing lens, is arranged on one side of an object to be measured and forms an acute included angle with a vertical line, and the three LED lamps are arranged in an equilateral triangle shape and are positioned behind a biconvex focusing lens; one of the three paths of LED lamps is a measuring
light source, the other two paths of LED lamps are reference light sources, wavebands of all the light sources are different, and the light sources are integrally positioned on the other side of the object to be measured and are symmetrical about a vertical line with the
photodiode detector; the upper computer controls the drive circuit to output three paths of control signals with the same frequency, the same duty ratio, the
phase difference of 120 degrees and the real-time adjustable phase amplitude to control the three paths of LEDs to be turned on alternately, and the three paths of LED lamps emit light rays which are incident through the biconvex focusing lens to irradiate an object to be measured. After
diffuse reflection of an object to be detected, the light is converged by the plano-concave focusing lens and then irradiates the
photodiode detector, the output end of the photodiode detector is connected to the input end of the pre-amplification circuit, and the output end of the pre-amplification circuit is connected to the upper computer. The three LED lamps irradiate after beam expanding and focusing, emergent light rays are approximately combined into parallel light,
light source detection surfaces basically coincide, the
light spot coverage range is large, the
measurement precision is high, the three LED lamps compensate each other through two groups of comparison results of one measuring
light beam and two reference light beams, the
color difference can be well eliminated, and the measurement accuracy is high. The influence caused by uncontrollable factors such as particle
size difference is avoided.