1529 - The Fresnel Biprism Experiment Based on CMOS Imaging Analysis

Abstract

The measurement of the wavelength of a monochromatic source of light with the Fresnel’s biprism is a fundamental experiment in most Universities. In this experiment, the determination of distance between two virtual light sources is necessary for the calculation of the wavelength of light. However, the presence of the aberration of lens results in an erratic distance between virtual source by using conjugate foci method, which leads to an erratic wavelength. To solve this, we used a CMOS detector to record magnified images and diminished images. The accurate distance between two virtual light sources was obtained with digital images processing, thereby reducing the uncertainty of measurement of the wavelength. The deviation between the measured wavelength of sodium light from CMOS imaging analysis method and the average wavelength at 589.3 nm calculated by two wavelengths of sodium yellow light is only 0.3%, which is smaller than the deviation from traditional method.