Light detector with length-adjustable shading cylinder

The utility model relates to the technical field of light detectors, in particular to a light detector with a length-adjustable shading cylinder. A first shading cylinder is mounted on one side of the connecting plate; a U-shaped block is mounted at the top of the first shading cylinder; a circular groove is formed in one end of the U-shaped block; a rotating block is rotationally connected to the inner wall of the U-shaped block; through the arrangement of the U-shaped block, the rotating block and the square block, when the length of the first shading cylinder needs to be adjusted, the second shading cylinder can be taken out, then the square block is rotated, the rotating block is arranged on the periphery of the long rod in a sleeving mode, and then the square block is rotated, so that splicing of the first shading cylinder and the second shading cylinder can be achieved; therefore, the length of the first shading cylinder is adjusted, and the situation that detection data is easily affected due to insuff