Type 74 island depression angle rangefinder

In 1970, the Artillery Department of the General Staff Department issued an assignment to the 3304 Factory (Nanjing Optical Instrument Factory) to develop an island depression rangefinder. The 3304 factory took one year to complete the design task and prototyped in 1972. On January 2, 1975, the Artillery Commission approved the design and finalization and named it '1974 Island Depression Range Mirror'. On September 20, 1978, the Artillery Commission approved the production and finalization. In the same year, he won the Science and Technology Progress Award of the National Science Conference.

The mirror is mainly used to monitor the targets of naval ships. Main performance: magnification 10 times, field of view 7 degrees, exit pupil diameter 6 mm, exit pupil distance 18.2 mm, light transmittance 57.5%, resolution not less than 4 seconds, range measurement range 2000m-20000m, mirror weight 9.25 It weighs 22.5 kg, together with the tripod, mirror box and spare accessories. The mirror began production in 1975 and ceased production after 1981.