習用共路徑架構具有高穩定度、高解析度、架構簡單的優點。不過共路徑架構大多是將雷射聚焦在光柵上進行繞射，雷射聚焦在光柵上光點直徑僅有約0.1mm，聚焦光束設計造成光學尺對光柵製造品質、與光柵上髒污變得非常敏感，產生難以補償的量測誤差。 本文提出了一種非聚焦共路徑雷射光學尺(Non-focused common-path Laser Encoder，以下簡稱NFCPLE)，在沒有將雷射聚焦情況下可有效克服過往共路徑架構遇到的瓶頸，NFCPLE對於光柵本身品質要求也較類似架構來得低。另外IC-Haus LSC感測器減少了光學元件數目，可減少光學元件之間的對位誤差。 本研究利用商用HP5529A干涉儀進行NFCPLE量測性能實驗評估，並進行誤差分析。實驗結果顯示，在10mm行程內，商用HP5529A干涉儀與NFCPLE的平均差量為185.31nm。而NFCPLE於三小時系統穩定度量測中產生漂移量為3.8±0.5nm，解析度約1.6±0.5 nm。綜合本研究的實驗評估與分析，可知NFCPLE在超精密機械應用相當有潛力。 Commonly usedcommon-path configuration.called (CPLE) has the advantages of high stability, high-resolution. ButCPLE almost is focused laser on grating.The focusedlaseron the grating is only about 100 mm in diameter. The optical scale is sensitive to grating manufacturing quality and grating dirty because of focused laser designed. This study proposes a non-focused common-path laser encoderdevice called (NFCPLE). NFCPLE can effectively overcome the problems in the past CPLE without focused laser design.NFCPLE compared with CPLE for the grating quality requirements is also much low.MoreoverIC-Haus LSCphotodetector reduces optical elements. With this technique, the effect of optical element error can be greatly reduced. In this study, NFCPLE conduct experimental evaluation of performance test and error analysis with HP5529A interferometer for offset evaluation, it is displayed in the analysis and the experimental results. In the displacement of 10 mm, the average differential of NFCPLE was 185.31nm with HP5529A interferometer. The time dependent drift of NFCPLE was measured for a period of three hour and was found to be 3.8 ± 0.5 nm with 1.6 ± 0.5 nm resolution. It is therefore shown that NFCPLE has enormous potential forfuture development.