Thin sample refractive index by transmission spectroscopy.

Area of Science:

• Optical Physics
• Materials Science
• Metrology

Background:

• Accurate refractive index determination is crucial for optical materials characterization.
• Traditional methods often require precise sample thickness measurements, which can be challenging for thin films.

Purpose of the Study:

• To develop and demonstrate a novel technique for measuring the refractive index of thin transparent samples.
• To achieve high absolute accuracy (<1 x 10^-4) across a broad wavelength range.
• To eliminate the need for independent sample thickness determination.

Main Methods:

• Combining transmission spectroscopy with a limited number of refractometer index measurements.
• Utilizing independent index measurements to bypass the requirement for thickness measurement.
• Applying the method to transparent glass samples approximately 50 micrometers thick.

Main Results:

• Achieved absolute refractive index accuracies better than 1 x 10^-4 at hundreds of wavelengths.
• Demonstrated high accuracy fits to Cauchy curves with RMS accuracies less than 3 x 10^-5 from 415 to 1610 nm.
• Successfully measured refractive indices without prior knowledge of sample thickness.

Conclusions:

• The combined spectroscopy and refractometry technique offers a robust and accurate method for thin film optical characterization.
• The developed method overcomes limitations of traditional refractive index measurement techniques.
• Further considerations for optimizing accuracy at this level are discussed.