Error-reduced channeled spectroscopic ellipsometer with palm-size sensing head

Abstract

This paper describes a newly developed prototype system of the channeled spectroscopic ellipsometer ͑CSE͒. The new system has a feature that the major systematic and random error sources of the previous CSEs are effectively reduced or compensated for. In addition, the prototype preserves the advantageous features of the CSE in that it has a palm-size sensing head and that its acquisition time is as fast as 20 ms. Its performance is experimentally examined by use of 12 films whose thicknesses are ranging approximately from 3 to 4000 nm. The film thicknesses measured by the new CSE show good agreements with the ones by the rotating-compensator spectroscopic ellipsometer. The stability of the film-thickness measurement of the new CSE against the temperature change from 5 to 45°C is less than 0.11 nm. The CSE can open up new applications of the spectroscopic ellipsometers in which the compactness, the simplicity, and the rapid response are important.

Robust Wavelength-Scanning Interferometer Based on Channeled Spectropolarimetry

“…The second feature of this interferometer is that the unwanted effect of temperature variation can be compensated by use of the so-called self-calibration technique originally developed for the channeled spectropolarimeter [6], [7]. Even though the interferometer has no spatial separation and thereby is immune to mechanical vibration, the phase shifts φ 1 (σ) − φ 2 (σ) and φ 1 (σ)+φ 2 (σ) can fluctuate due to another environmental perturbation, specifically the temperature fluctuation.…”

“…To enhance the stability of the wavelength-scanning interferometry, we developed a novel configuration [4] by combining methods in channeled spectropolarimetry [5]- [7] and polarimetric common-path cyclical interferometry [8], [9]. The channeled spectropolarimetry is the wavelength-resolved polarimetry without using mechanical or active elements for polarization modulation.…”

Snapshot polarized light scattering spectroscopy using spectrally‐modulated polarimetry for early gastric cancer detection

“…It is essential to accurately reconstruct the Stokes parameters from the modulated spectrum of scattered light. However, the state-of-the-art reconstruction method, Fourier transform method (FTM) [34][35][36][37][38], uses the Fourier transform to extract the Stokes parameters from the modulated spectrum in the frequency domain [35]. Although straightforward, FTM still has a series of problems such as channel cross-talk, highfrequency loss, and the need for phase calibration [37,[39][40][41], especially the reconstructed spectral resolution is lower than the used spectrometer, which makes the FTM unsuitable to the PLSS, and requires a relatively high spectral resolution.…”

Chip-scale full-Stokes spectropolarimeter in silicon photonic circuits

“…Over the last decade, the demand for compact, cost-effective, and low-power spectropolarimeters has increased dramatically. Recently, some miniature architectures of such devices have been demonstrated [9][10][11][12]. However, these works were still exploring the possible improvements of traditional free-space optical components.…”