Small-size internal thread measurement method achieved on universal length measuring gauge and device

The invention discloses a small-size internal thread measurement method achieved on a universal length measuring gauge and a device. According to the method, the universal length measuring gauge is adopted, an insulated work table (20) is provided with an internal thread measurement device (12), a tiny optical sensitive lever mechanism arranged on the internal thread measurement device (12) according to an optical sensitive lever principle comprises a T-shaped measurement head (1) connected with a lever (2) through a measurement rod, the lever (2) is connected with a force measurement spring (6) and a reflective mirror (5), a reticle (4) is arranged between a light source (3) and the reflective mirror (5), the upper portion of the lever (2) is connected with an objective lens (7), the objective lens (7) is connected with a CCD camera (8), and the CCD camera (8) is connected with a computer (9). The method and device are related to geometry optical design and mechanical structure design of a length metering in