The invention relates to a dynamic angle measurement error 
detector used in a photo-electric axial angle 
encoder. A fixation part of a to-be-tested 
encoder is arranged on a base of the 
detector, a rotary part of the to-be-tested 
encoder is connected with a revolving shaft by a 
coupling joint, a polyhedron is fixed on the revolving shaft of the 
detector, a dynamic signaling 
autocollimation aims at a reflecting surface of the polyhedron, and a rotator of a 
torque motor is connected with the revolving shaft. During the detection, the 
torque motor is controlled by a computer to continuously rotate at a certain speed, and the revolving shaft, the rotary part of the to-be-tested encoder and the polyhedron are driven to rotate by the 
torque motor. When one operating angle of the polyhedron is turned, and the operating surface of the polyhedron is perpendicular to an 
optical axis, a trigger circuit sends out trigger impulses. 
Encoder values can be sampled after a 
data acquisition system probes trigger impulse signals. After the rotary part of the to-be-tested encoder rotates a circle, a group of sampling values can be obtained, and dynamic angle measurement errors of the to-be-tested encoder can be calculated by a data-
processing system of the computer. The dynamic angle measurement error detector can be used for detecting the dynamic errors of the photo-electric axial angle encoder and has higher precision.