| 摘要: | 隨著科技的進步，鏡頭的應用也越來越廣泛，對於光學模組的品質要求也逐漸提升，但在製造的過程中難免會產生劣質品，造成透鏡產生偏心或傾斜等誤差，或是產生其他不必要的像差，因此為了達到完美的成像效果，品質的控管也是非常重要，因此我們可以透過量測波前結合計算調製傳遞函數(MTF)的方法，從這兩個資訊交錯評判鏡頭的好壞。本文以四波橫向剪切干涉儀(QWLSI) 波前檢測儀，結合計算MTF進行檢測，因為QWLSI解析度和測量精度較高、擁有較大的動態範圍、檢測快速以及架構簡單與容易操作等多項優點，故以此技術作為基礎來檢測波前像差以及利用波前像差重建MTF，評估待測物之光學成像品質。
對於QWLSI之量測方法，首先，QWLSI須選擇放置在待測樣品後發散光的範圍進行量測，使還原波前的計算過程能完整的採集資訊，並且利用尋找干涉點對比度最佳位置搭配自動軸控決定CCD測量位置，校正量測誤差，以及分析框選掩模之重要性，引入自動找圓演算法，自動框選干涉圖圓心，並且多次測試自動找圓演算法，其找到的圓心位置與半徑標準差皆在0.5 pixel以下，利用演算法可避免人為上的實驗誤差，因此最後量測可以結合自動軸控CCD量測位置以及自動找圓達到自動化檢測。接著測試QWLSI對於波前量測之穩定性達1/449 waves (RMS)精確度達1/246 waves (RMS)，動態範圍之量測至少可達160 μm，並且與目前公認的Trioptics商用MTF量測機台相比其誤差低於1.3 %。因此透過結合擁有特有優勢的QWLSI量測技術與計算MTF作為鏡頭檢測技術，能夠有效的評判鏡頭的好壞，並且搭配自動化的技術，未來的趨勢有機會能夠成為線上的檢測產品。
;With the progress of technology, the application of lenses has become more extensive, and the quality requirements for optical modules have gradually increased. However, in the process of manufacturing, inferior products are inevitably induced, causing errors such as eccentricity or tilting of the lens, or Other unnecessary aberrations. Therefore, quality control of lens is very important to achieve perfect imaging. And this paper shows that we can calculate the modulation transfer function (MTF) by measuring the wavefront, to compare the lenses in good or bad from the information of wavefront and MTF. In this paper, the four-wave transverse shear interferometer (QWLSI) wavefront detector is combined with the calculation of MTF for detection, because QWLSI has high resolution and measurement accuracy, large dynamic range, fast detection, simple structure and easy operation. As a result, the technique is used as a basis to detect wavefront aberrations and to reconstruct MTF using wavefront aberrations to evaluate the optical imaging quality of the object under test.
For the measurement method of QWLSI, firstly, QWLSI must select the range of diverging light to place after the sample to be tested for measurement, so that the calculation process of the restored wavefront can completely collect information, and then using to find the placement of the better contrast of the interference point to determine the CCD measurement position and to match the automatic axis to control it. Next, the paper analyzes the importance of the frame selection mask. It introduces an automatic circle finding algorithm to select the center of the interferogram automatically, and then tests the algorithm to find the center of the circle repeatedly. The standard deviation of position and radius is below 0.5 pixel. The algorithm can avoid artificial error. Therefore, the final measurement can be combined with the automatic axis control CCD measurement position and automatic circle finding to achieve automatic detection. After testing, QWLSI is tested the stability of the wavefront measurement to 1/449 waves (RMS), the accuracy of it to 1/246 waves (RMS), the dynamic range measurement of at least 160 μm, and an error of less than 1.3% compared with the commercial measurement machine of MTF (Trioptics).
Therefore, by combining the QWLSI measurement technology with advantages and the calculation of MTF as the lens detection technology, it is possible to effectively judge the quality of the lens, and it is with the automation technology, the future trend has the opportunity to become an online inspection product. |
