Apparatus used for small-size internal screw thread measurement on universal length meter

The utility model discloses an apparatus used for small-size internal screw thread measurement on a universal length meter. The apparatus comprises a universal length meter, and an internal screw thread measurement apparatus (12) is arranged on an insulation working bench (20). The internal screw thread measurement apparatus (12) is provided with a microminiature optics sensitive lever mechanism according to an optics sensitive lever principle and comprises a T-shaped measuring head (1) which is connected with a lever (2) through a measuring rod. The lever (2) is connected with a force measurement spring (6). The lever (2) is connected with a reflective mirror (5). A reticle (4) is arranged between a light source (3) and the reflective mirror (5). An objective lens (7) is arranged above the lever (2). The objective lens (7) and a CCD camera (8) are connected. The CCD camera (8) and a computer (9) are connected. The utility model relates to geometrical optical design, machinery structural design and computer video image displaying and processing technology of the length meter, and is applied to a metering apparatus equipped with computer image displaying and processing, Combination of tradition and modern is realized, technical content of the universal length meter is increased and using range of the universal length meter in the prior art is expanded.