FMCW LiDAR 是一種能夠量測目標物的距離和速度，同時掃描並獲取影像的技術。它在智慧感測領域的應用非常廣泛，特別在自動駕駛汽車、工業 4.0 和虛擬混合實境等領域有很大的需求。這項技術可以提供更多的資訊，使得相關應用變得更加多樣與活躍性。
FMCW LiDAR 是利用調變連續波雷射 (FMCW Laser) 做為量測距離的訊號光源，為了能縮小 FMCW LiDAR 的系統大小，本論文提出基於光纖的數種採樣方法。我們選擇使用希爾伯特轉換 (Hilbert Transform) 來修正連續波光學雷達中非線性掃頻造成的量測誤差。同時搭配數據採集(Data Acquisition, DAQ)的Resample Points與調變波長的範圍，不只可以大幅縮短輔助干涉儀需要的光程差，達到縮小體積的目的，還可以降低對DAQ採樣率的要求，使FMCW LiDAR成本大幅減少。最後再結合晶片型的Lattice Filter、直波導與Mach-Zehnder Directional Coupler (MZDC)，使整個系統邁向晶片化。由於是提取目標物反射回來相位資訊，因此 FMCW LiDAR 的系統可以有效地降低相位雜訊與提升靈敏度，並與平衡光偵測器 (Balanced Photodetector, BPD) 相結合，在下一代 FMCW LiDAR 系統中開闢了新的可能性。

在本論文實驗量測中，為了滿足Nyquist Theorem，採樣頻率必需為原始頻率的兩倍，也即是說DAQ採樣率的一半是系統可量測的最高頻率。由於光源是頻率隨時間的線性調變，所以DAQ的時間採樣率，即代表光源雷射頻率。主干涉儀之干涉波包的頻率週期與待測距離有關，當主干涉儀光程差(Optical Path Difference, OPD)愈大，提高DAQ採樣率才可將準確量測干涉波包。以實驗室1 Mega Sample Rate之DAQ為例子，為滿足Nyquist Theorem之重採樣頻率，0.5 Mega Sample Rate相對應主干涉儀的OPD為10公尺以上，當OPD超過10公尺時，我們提出以輔助干涉儀來做Hilbert Transformation重採樣，以準確測量主干涉儀之干涉波包，如此可降低對DAQ採樣率的需求，同時此重採樣之輔助干涉儀的光程差可縮小為主干涉儀光程差的1/10，其重採樣頻率準確度是可以預期的。之後結合晶片型的Lattice Filter、直波導與MZDC證明了線寬經過補償後會更優秀。我們使用上述方法，在1 Mega Sample Rate之DAQ的最終偵測距離增加到1052.5 cm，輔助干涉儀OPD為105cm，FWHM 為0.0043 cm，Standard Deviation 為0.006 cm。

Frequency-modulated continuous-wave light detection and ranging (FMCW LiDAR) is a technology that can measure the distance and speed of a target and scan and acquire images simultaneously. It has a wide range of applications in intelligent sensing, especially in self-driving cars, Industry 4.0, and virtual mixed reality. LiDAR can provide more information and make the related applications more diversified and active.
FMCW LiDAR uses FMCW Laser as the signal light source to measure the distance. For the FMCW LiDAR system size reduction, this thesis proposes several sampling methods based on optical fiber. Hilbert Transformation is chosen to correct the measurement error caused by the nonlinear sweeping of the continuous wave in LiDAR. Meanwhile, with data acquisition (DAQ) resample points and wavelength range modulation, not only the optical path difference of the auxiliary interferometer can be significantly shortened to achieve the purpose of small size, but also the requirements for DAQ sampling rate could be further enhanced so that the cost of FMCW LiDAR will be reduced. Finally, the system is chip-based by combining Lattice Filter, straight waveguide, and Mach-Zehnder Directional Coupler (MZDC). By extracting the phase information reflected from the target, the FMCW LiDAR system can effectively integrate the balanced photodetector (BPD), reduce phase noise and increase sensitivity to open up new possibilities in the next-generation FMCW LiDAR system.
In the experimental measurements of this paper, to satisfy the Nyquist Theorem, the sampling frequency must be twice the original frequency, which means the DAQ sampling rate should be half of the system's maximum measurable frequency. Since the light source exhibits frequency modulation over time, the DAQ's time sampling rate represents the frequency of the laser light source. The frequency period of the interference wave packet in the main interferometer is related to the measured distance. When the optical path difference (OPD) of the main interferometer is larger, higher DAQ sampling rates are required to accurately measure the interference wave packet. For instance, in the case of a 1 Mega Sample Rate DAQ in the laboratory, to meet the Nyquist Theorem's resampling frequency, 0.5 Mega Sample Rate corresponds to the OPD of the main interferometer is more than 10 meters. When the OPD exceeds 10 meters, we propose using the auxiliary interferometer for Hilbert Transformation resampling to accurately measure the interference wave packet of the main interferometer. This approach reduces the demand for the DAQ sampling rate, and at the same time, the resampled optical path difference of the auxiliary interferometer can be reduced to 1/10 of the main interferometer's, ensuring the accuracy of the resampling frequency.
Subsequently, by integrating chip-type Lattice Filter, straight waveguides, and MZDC, the compensation of linewidth is proven to be superior. Using the aforementioned methods, the final detection distance with a 1 Mega Sample Rate DAQ is increased to 1052.5 cm, the OPD of the auxiliary interferometer was 105 cm, with a FWHM of 0.0043 cm, and a standard deviation of 0.006 cm.

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