Wavelength modulation spectrometer for studying the optical properties of solids

Area of Science:

• Spectroscopy
• Optical Physics
• Analytical Chemistry

Background:

• Wavelength derivative spectroscopy enhances optical structure analysis compared to conventional methods.
• A key challenge is removing the derivative of incident light intensity (dI(0)/dlambda) from spectra.
• Existing methods often require closely matched components for accuracy.

Purpose of the Study:

• To describe a sensitive double beam wavelength modulation spectrometer.
• To demonstrate accurate removal of the dI(0)/dlambda spectrum.
• To present a spectrometer design that does not require closely matched components.

Main Methods:

• Utilized a double beam wavelength modulation spectrometer.
• Implemented a servo loop to continuously optimize the removal of dI(0)/dlambda.
• Controlled the gain of the reference channel via the servo loop.

Main Results:

• The described spectrometer accurately removes the dI(0)/dlambda spectrum.
• The servo loop effectively optimizes the removal process.
• Achieved double beam accuracy without requiring closely matched components.

Conclusions:

• The developed spectrometer offers a practical solution for accurate wavelength derivative spectroscopy.
• The servo-controlled gain adjustment is crucial for removing incident light intensity artifacts.
• This design simplifies spectrometer construction while maintaining high accuracy.