Effect of Rayleigh Range on the Accuracy and Measurement Range of Refractive Index for Brix Determination

Mohseniafkham, Ali; Valipourhafshejani, Meysam; Tavassoli, Seyed Hassan

doi:10.48308/piadm.2026.244389.1022

Effect of Rayleigh Range on the Accuracy and Measurement Range of Refractive Index for Brix Determination

Document Type : Original Article

Authors

Ali Mohseniafkham

Meysam Valipourhafshejani

Seyed Hassan Tavassoli

Laser and Plasma Research Institute, Shahid Beheshti University, Tehran, Iran

10.48308/piadm.2026.244389.1022

Abstract

Optical techniques have been widely employed in various sensing and analytical applications in recent years. In this regard, considerable efforts have been devoted to the development and optimization of refractometry-based methods for Brix measurement. In this study, the proposed system was modeled and simulated, with primary emphasis mainly placed on optimizing the angular distribution of the rays via careful adjustment of the Rayleigh range and focal length. The results clearly indicate that this parameter is an important factor in the proper formation of the critical angle and in improving overall system performance. Also, it was found that the selection and positioning of optical components, including the light source, prism, lenses and detector, along with the adjustment of this parameter, have a considerable effect on the quality of the bright–dark boundary and the measurement accuracy. Accordingly, simultaneous optimization of these factors is necessary to achieve optimal performance of the refractometry system.

Keywords

Abbe refractometer

Total internal reflection

Critical angle

Brix

Rayleigh range

Zemax

Refractive index

sugar