Light-cut method, also known as double-barreled microscope microscope 9J (JBQ) □ 9J cutting microscope uses light microscopic light-section method is based on the measurement of parts machined surface roughness, can determine the national standard (GB1031-68) prescribed ▽ 3- ▽ 9 surface finish (surface roughness of 12.5 -0.2). For surface scratches, groove or the depth of the defect can also be used in some measure. Features a light microscope method is cut without damaging the surface of the situation, is an indirect measurement method to determine the pattern marks irregularities after that to go through calculations. Light cutting microscope for enterprise metering chamber, precision parts manufacturing enterprises, scientific research and other units, is one of the typical instrument of the tertiary institutions teaching.