應用於光譜感測器陣列之盲目光強度不均勻及錯誤感測器修正演算法

Blind Nonuniformity Correction and Faulty Sensor Detection Methods for On-Chip Spectrum Sensor Array

林軒宇(Hsuan-Yu Lin)

指導教授 ： 張正春

國立臺北科技大學/電資學院/電機工程系所/碩士(2012年)

https://doi.org/10.6841/NTUT.2012.00140

摘要

以濾波器陣列製成的光譜感測元件已經被認為是實現微型光譜儀一個可靠的架構，藉由使用多個具有不同頻譜響應的光譜感測器，可以判斷被測物光譜的特性。然而由於低成本且微型的輸入介面，輸入光對於每個感測器的強度可能會不平均。除此之外，每個感測器的輸出都可能包含來自CMOS感測器的脈衝干擾。
未預期的光強度不均勻性將對量測頻譜造成碩大的影響，雖然精緻的光學儀器可以抑制這個問題，我們仍使用演算法處理這個問題因為(1)即便是精緻的光學儀器，仍會有5%至10%的光不均勻性，(2)相較之下，現今透過演算法解決這個問題會使成本下降。因此我們提出一個迭代性的盲目修正演算法以解決這個光強度不均的問題。只要光強度在每個感測器之間是平順變化，這個被提出的演算法便可在沒有任何其他資訊的狀況下解決問題。使用這個被提出的演算法無論對模擬還是在實測的數據都有顯著的改善。
脈衝性的干擾常因為傳輸錯誤、感測器的功能不正常、記憶體存取的問題還有在類比轉數位時的時序問題而產生。在大多光譜感測器陣列的應用領域中，這樣的干擾會大幅影響系統效能，所以修正這些被干擾的感測器是必須且急需的。使用在編碼理論中「線性區塊碼」的概念，這篇論文提出一個修正錯誤感測器的方法。

關鍵字

脈衝雜訊 ； 光不均勻性 ； 盲目修正演算法 ； 微型光譜儀 ； 光譜感測器陣列 ； 錯誤感測器

並列摘要

Filter-array spectrum sensors have been a promising structure that can be used to realize miniature spectrometers or spectrometers on-a-chip. By using multiple spectrum sensors with different spectral responses, the spectrum of a measurement object can be characterized. However, due to the low-cost and miniature design of the input optic interfaces, the intensity of the input light shining onto the imager of the sensor array may not be uniform. In addition, the sensor outputs may contain impulsive perturbation from the CMOS imager.
The unmodeled input nonuniformity could lead to a severe distortion in the spectrum measurement. Although the input nonuniformity can be alleviated by introducing dedicated input optic interface, we are interested in tackling this issue from an algorithmic perspective because (1) dedicated optics could still render 5%-10% intensity variation, and (2) the cost of computation power in electronics is potentially much lower than the cost of optics nowadays. Accordingly, we propose an iterative blind correction algorithm to solve the input light nonuniformity issue. The algorithm is based on the assumption that variation of input light intensity shall change smoothly, and hence requires no additional information. With the proposed iterative blind correction algorithm, significant improvement on the quality of spectrum reconstruction is obtained in both simulation and experimental studies.
Impulsive perturbations often occur due to transmission errors, malfunctioning pixel elements in the camera sensors, faulty memory locations, and timing errors in analog-to-digital conversion. It should be noticed that most of the spectrum sensor applications are sensitive to sensor readout perturbation. If the impulsive perturbation exists, it reduces the system performance dramatically, so it is imperative and even indispensable to correct these faulty pixels. Based on the concept of linear block code in coding theory, this thesis proposes an approach to correct the faulty pixels.

並列關鍵字

impulsive noise ； input nonuniformity ； blind correction algorithm ； miniature spectrometer ； spectrum sensor array ； faulty sensor

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