本研究提出使用自製PQ:PMMA VBG作為半導體雷射外部共振腔反射鏡，達成頻率調制連續波(FMCW)雷射雷達系統。首先，將自製感光高分子光學壓克力PQ:PMMA以532 nm綠光雷射進行曝光後，將PQ:PMMA材料製作成反射式體積布拉格光柵(VBG)，回饋1064 nm半導體雷射後，達成單縱模雷射輸出。再將自製PQ:PMMA VBG固定於壓電制動元件(PZT)上，以訊號產生器供給電壓調制PZT產生長度變化，調控半導體雷射外部共振腔的腔長，以此調變此單縱模半導體雷射之輸出波長，達到FMCW雷射發射端架構。本研究之距離量測是以類似麥克森干涉儀的架構，量測兩道反射光相干涉產生的拍頻(Beat Frequency)訊號來計算距離。本研究之FMCW LiDAR系統最適宜量測距離約為五至九公尺，而系統量測之距離標準差約在十公分內。

An external cavity diode laser(ECDL) feedback with a homemade PQ:PMMA VBG is served as the tunable laser of a FMCW LiDAR system.
Photopolymer material PQ:PMMA is exposed by a 532 nm laser using two-beam interference scheme to achieve a volume Bragg grating(VBG). The VBG is used to feedback a 1064 nm diode laser to reach single longitudinal mode laser output. The VBG is attached to a PZT controlled by a function generator to modulate the length of the external cavity, and thus made a FMCW laser source. The FMCW range finding system is similar to a Michelson interferometer. Two reflected beam will interfere on the sensor plane. The beat frequency is measured and the object distance can be calculated. In this thesis, the optimum measurement distance of our FMCW LiDAR system is approximately 5 m to 9 m, while the standard deviation of the system measurement is within approximately 10 cm.

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