Enhanced Static Modulated Fourier Transform Spectrometer for Fast Approximation in Field Application.

Ju Yong Cho,Won Chun Oh,Won Kweon Jang

doi:10.3390/molecules26113312

Abstract

We discuss the data sampling frequency, the spectral resolution, and the limit for non-aliasing in the static modulated Fourier transform spectrometer based on a modified Sagnac interferometer. The measurement was performed in a very short 4 ms, which is applicable for real time field operation. The improved spectrometer characteristics were used to investigate the spectral properties of an InGaAs light emitting diode. In addition, The measured spectral peak was shifted from 6420 cm−1 to 6365 cm−1, as the temperature increased from 25 °C to 40 °C, when the operating current is fixed to be 0.55 A. As the applied current increased from 0.30 A to 0.55 A at room temperature, the spectral width was broadened from 316 cm−1 to 384 cm−1. Compared to the conventional Fourier transform spectrometer, the measured spectral width by the static modulated Fourier transform spectrometer showed a deviation less than 10%, and the spectral peak shift according to the temperature rise showed a difference within 2%.

Highlights

We suggest the static modulated Fourier transform spectrometer based on the modified Sagnac interferometer features having higher optical throughput and longer optical path difference compared to other static modulated Fourier transform spectrometers
The spectrum of InGaAs light emitting diode was measured using the static modulated Fourier transform spectrometer based on the modified Sagnac interferometer
In the temperature-dependent energy band gap analysis, the spectral resolution of the static modulated Fourier transform spectrometer was 34 cm−1 and the spectral width was 384 cm−1, of which the difference was within 10% compared to the theoretical and the monochromator measured values

Summary

Introduction

The research for the static modulated Fourier transform spectrometer of various structures has been reported, because it can provide the fast and outdoor measurement with remote sensing operation. It is still suffering from relatively low spectral resolution and data reliability. The systems of diffraction distribution need a long measurement time to compensate the weak intensity of diffracted signal that pass through the slit It has a drawback in spectral resolution when it measures the optical properties of material in the infrared range, because the diffraction angle is becoming smaller as the wavelength is becoming longer [1,2]. The Fourier transform spectrometer is a better choice in finding out the spectroscopic properties of materials with absorption peaks in the infrared region, because many harmful or toxic materials have their spectral absorption peaks in the infrared region

Methods

Results

Conclusion