GB/T 39865-2021Method for measuring refractive index of uniaxial optical crystals (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

1 Scope

This standard specifies the environmental requirements, measurement principles and methods, testing instrument requirements, and testing methods for the refractive index measurement method of uniaxial crystal optical crystals. Sample preparation, measurement procedures, data processing and uncertainty evaluation.

This standard applies to the refractive index measurement of uniaxial crystal optical crystals, and the refractive index measurement of other optical crystals can be implemented by reference.

2 Measurement environment requirements

The measurement environment requirements are as follows.

a) Temperature. 21°C±3°C, the temperature change during the measurement is not more than 0.5°C;

b) Relative humidity. not more than 30%;

c) Vibration. meet the vibration requirements of the equipment to the environment.

3 Measuring principle

The measuring principle of the vertical incidence method for measuring the refractive index of a uniaxial crystal optical crystal is shown in Figure 1.By measuring the incident light passing through the crystal to be tested The refraction angle and the incident angle are calculated by the law of refraction to obtain the refractive index of the crystal under test. The measured crystal is processed into a right-angle prism sample, and the optical axis of the crystal is positioned In the right-angle plane of incidence, when unpolarized parallel light of a specific wavelength is incident perpendicularly to the right-angle plane, due to the difference in refractive index of o-ray and e-ray, the After the crystal is refracted at different angles on the exit surface, the refraction angle of o light io and the refraction angle of e light and the incident The angle of incidence theta is calculated by formula (1) and formula (2) to obtain the refractive index no and ne of the sample. sinio sintheta (1) sinie sintheta (2)

Where. no---o light refractive index; ne---e light refractive index; io---o light refraction angle; ie---e light refraction angle.