CommSensLab, Technical University of Catalonia/UPC, 08034 Barcelona, Spain.
Department of Electronics and Nanoengineering, Millilab, Aalto University, 02150 Espoo, Finland.
Sensors (Basel). 2022 Apr 22;22(9):3237. doi: 10.3390/s22093237.
Improving the longitudinal modes coupling in layered spherical structure contributes significantly to corneal terahertz sensing, which plays a crucial role in the early diagnosis of cornea dystrophies. Using a steel sphere to calibrate reflection from the cornea sample assists in enhancing the resolution of longitudinal modes. The requirement and challenges toward applying the calibration sphere are introduced and addressed. Six corneas with different properties are spotted to study the effect of perturbations in the calibration sphere in a frequency range from 100 GHz to 600 GHz. A particle-swarm optimization algorithm is employed to quantify corneal characteristics considering cases of accurately calibrated and perturbed calibrated scenarios. For the first case, the study is carried out with signal-to-noise values of 40 dB, 50 dB and 60 dB at waveguide bands WR-5.1, WR-3.4, and WR-2.2. As expected, better estimation is achieved in high-SNR cases. Furthermore, the lower waveguide band is revealed as the most proper band for the assessment of corneal features. For perturbed cases, the analysis is continued for the noise level of 60 dB in the three waveguide bands. Consequently, the error in the estimation of corneal properties rises significantly (around 30%).
改善层状球形结构中的纵模耦合对角膜太赫兹传感有重要贡献，这在角膜营养不良的早期诊断中起着至关重要的作用。使用钢球校准角膜样本的反射有助于提高纵模的分辨率。介绍并解决了应用校准球的要求和挑战。对六个具有不同特性的角膜进行了探测，以研究在 100GHz 至 600GHz 的频率范围内校准球中的扰动对纵向模式的影响。采用粒子群优化算法，在准确校准和扰动校准的情况下，考虑角膜特性的定量分析。在第一种情况下，在 WR-5.1、WR-3.4 和 WR-2.2 波导频段，信噪比分别为 40dB、50dB 和 60dB 时进行了研究。如预期的那样，在高 SNR 情况下可以实现更好的估计。此外，较低的波导频段被揭示为评估角膜特征的最合适频段。在受扰情况下，在三个波导频段中继续进行噪声水平为 60dB 的分析。结果，角膜特性估计的误差显著增加（约 30%）。
