Optical and mechanical design for V-prism refractometer with high accuracy

For the problems that the traditional V-prism refractometer employs the optical dial and the visual alignment is unable to meet the demands for the production line of modern optical glass and high-precision refractivity measurement, a kind of new general design scheme of high precision V-prism refractometer based on charge-coupled device (CCD) machine vision alignment was put forward in this paper, and the optical and mechanical structure design of the main components of the system, such as collimator, transmission mechanism, locking and fine adjustment mechanism, orientation measuring mechanism of shaft encoder was done. Additional, the detection error of the instrument was analyzed on the basis of the correction formula considering the air refractive index factors. The results show that the refractive index test accuracy reaches up to 310-6, the technical index requirements of the high accuracy V-prism refractometer are well satisfied.