Optical design of a refractometer with the liquid prism

Abstract

Here a refractometer with the liquid prism is proposed. It has a simple structure, low cost and a large measurable refractive index range. When the vertex angle of liquid prism is 30°, the measurable refractive index range is up to 1.00-3.86, while the common refractometers have only the measurable range of 1.30-1.70. The optical system of this refractometer is design, where the angle of field is 80° and the total length is 110mm. A linear array CCD is used as the image receiver. The design results show that MTF is 0.35 in the tangential surface and 0.55 in the sagittal surface at the Nyquist frequency of 70lp/mm and the full field. The MTF values of other fields are more than 0.6, and the maximum distortion is 0.37%.