focusing stop meaning in English

调焦光圈

This microscope is provided with achromatic objectives , wide field eyepieces , abbe condenser , adjustable built ? in light source , and coaxial coarse and fine adjustment with focus stop . . this microscope with his wide field eyepiece gives a nice and sharp image and is designed in a very modem way , it is designed for clinical experiments and classroom demonstration in medical and hygienic establishments , chemical laboratory , agricultural scientific research nets , research institutes and colleges as well as for the routine examination and research purpose in bioloy , bacteriology , cytology and pharmaceutical chemistry
本显微镜采用消色差物镜、广角目镜、阿贝聚光镜，连续可调的人工光源及带有限位置的同轴粗微动机构，视场广阔、成象清晰、设计先进，可供医疗卫生机构、化学试验室、农业科研系统、研究所及高等院校临床试验和教学示范，以及在生物学、细菌学、细胞学和药物化学等领域作常规检查和研究。