TWI420229B - Method for measuring modulation transfer function value of lens - Google Patents
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本發明涉及鏡頭檢測技術領域，尤其涉及一種測量鏡頭之調製傳遞函數值之方法。The present invention relates to the field of lens detection technology, and in particular, to a method for measuring a modulation transfer function value of a lens.
數位相機、攝像機及手機攝像頭等成像物體之影像品質主要取決於鏡頭之成像品質，而鏡頭之成像品質監控在於鏡頭之測試過程。調製傳遞函數值(Modulation Transfer Function, MTF)係分析鏡頭之解像力跟反差再現能力、綜合評價鏡頭之銳度、反差及解析度之重要參數之一。參見文獻：A simple method for determining the modulation transfer function indigital radiography; Fujita, H., Tsai, D-Y., Itoh, T., Department of Electronic & Computer Engineering, England, Gifu University; Medical imaging, IEEE transactions on; pages 34~39, Volume 11, Issue 1, March.1992。The image quality of an imaged object such as a digital camera, a video camera, and a mobile phone camera depends mainly on the imaging quality of the lens, and the imaging quality of the lens is monitored by the lens. Modulation Transfer Function (MTF) is one of the important parameters for analyzing the resolution and contrast reproducibility of the lens, and comprehensively evaluating the sharpness, contrast and resolution of the lens. See also literature: A simple method for determining the modulation transfer function in digital radiography; Fujita, H., Tsai, DY., Itoh, T., Department of Electronic & Computer Engineering, England, Gifu University; Medical imaging, IEEE transactions on; pages 34~39, Volume 11, Issue 1, March.1992.
常用之測量鏡頭調製傳遞函數值之裝置包括設有明暗相間之圖案之測試板、承載台、驅動單元、圖像感測器與處理器。測試板與圖像感測器相對設置。承載台用於放置待測鏡頭。驅動單元連接於承載台，用於驅動待測鏡頭於測試板與圖像感測器之間沿待測鏡頭之光軸上下移動，以使測試板之圖案於圖像感測器上形成圖像。圖像感測器用於感測經由待測鏡頭之成像之亮度最大值Imax 與最小值Imin 。所述處理器連接於所述圖像感測器，用於接收待測鏡頭所成像之亮度最值，根據公式MTF=(Imax -Imin )/(Imax +Imin )計算得到該成像之調製傳遞函數值，進而判斷鏡頭是否合格。A commonly used device for measuring the value of a lens modulation transfer function includes a test board having a pattern of light and dark, a carrier, a driving unit, an image sensor, and a processor. The test board is placed opposite the image sensor. The carrying platform is used to place the lens to be tested. The driving unit is connected to the carrying platform for driving the lens to be tested to move up and down along the optical axis of the lens to be tested between the test board and the image sensor, so that the pattern of the test board forms an image on the image sensor. . The image sensor is used to sense the luminance maximum value I max and the minimum value I min of the imaging via the lens to be tested. The processor is connected to the image sensor for receiving the brightness maximum value imaged by the lens to be tested, and calculating the image according to the formula MTF=(I max −I min )/(I max +I min ) The modulation transfer function value to determine whether the lens is qualified.
然，於測試過程中，承載台可能會相對於測試板或圖像感測器傾斜，導致承載於其上之待測鏡頭之光軸亦不與測試板或圖像感測器垂直，從而使圖像感測器感測到之亮度之最大值與最小值出現偏差，導致最終所得待測鏡頭之調製傳遞函數值不準確。However, during the test, the stage may be tilted relative to the test board or the image sensor, so that the optical axis of the lens to be tested carried thereon is not perpendicular to the test board or the image sensor, thereby The maximum value and the minimum value of the brightness sensed by the image sensor are deviated, resulting in inaccurate modulation transfer function values of the resulting lens to be tested.
有鑑於此，提供一種可準確測量鏡頭之調製傳遞函數值之方法實屬必要。In view of this, it is necessary to provide a method for accurately measuring the modulation transfer function value of the lens.
一種測量鏡頭調製傳遞函數值之方法，包括步驟：提供測試板、圖像感測器、承載台、處理器與待測鏡頭，所述測試板具有複數相對於測試板之中心對稱之測試圖案，所述圖像感測器與所述測試板相對，用於感測測試圖案經由待測鏡頭之成像，所述承載台用於承載待測鏡頭，其位於所述測試板與圖像感測器之間，所述處理器連接於所述圖像感測器，用於處理並獲得圖像感測器感測到之成像之調製傳遞函數值；使圖像感測器相對於待測鏡頭沿待測鏡頭之光軸移動從而獲得待測鏡頭對複數測試圖案以連續像距成像之連續調製傳遞函數值，並根據高斯公式獲得待測鏡頭之物距與該調製傳遞函數值之連續關係曲線；將待測鏡頭繞自身光軸進行多次等角度旋轉從而獲得複數測試位置，每個測試位置時分別對與該測試位置相應之一個測試圖案成像，並獲得該成像之調製傳遞函數值；於連續關係曲線上獲得與於該複數測試位置上獲得之複數調製傳遞函數值對應之複數物距值，並根據所述複數物距值調整承載台以使承載台與所述測試板於複數測試圖案處之間距值相等；使承載台相對於所述測試板沿待測鏡頭之光軸移動以測試待測鏡頭之準確調製傳遞函數值。A method for measuring a lens modulation transfer function value, comprising the steps of: providing a test board, an image sensor, a carrier, a processor, and a lens to be tested, the test board having a plurality of test patterns symmetric with respect to a center of the test board, The image sensor is opposite to the test board for sensing the imaging of the test pattern via the lens to be tested, and the carrier is configured to carry the lens to be tested, and the test board is located at the test board and the image sensor Between the processor, the processor is coupled to the image sensor for processing and obtaining a modulation transfer function value sensed by the image sensor; causing the image sensor to be relative to the lens to be tested The optical axis of the lens to be tested is moved to obtain a continuous modulation transfer function value of the lens to be tested for continuous image distance imaging, and a continuous relationship between the object distance of the lens to be tested and the value of the modulation transfer function is obtained according to a Gaussian formula; The lens to be tested is rotated a plurality of equal angles around its optical axis to obtain a plurality of test positions, and each test position is respectively imaged with a test pattern corresponding to the test position, and the result is obtained. Modulating the transfer function value; obtaining a complex object distance value corresponding to the complex modulation transfer function value obtained at the complex test position on the continuous relationship curve, and adjusting the carrying platform according to the complex object distance value to make the carrying platform The test board is equal in value between the plurality of test patterns; the stage is moved relative to the test board along the optical axis of the lens to be tested to test the accurate modulation transfer function value of the lens to be tested.
本技術方案提供之測量鏡頭之調製傳遞函數值之方法於測試前校正承載台相對於測試板之傾斜。再藉由移動待測鏡頭進行測試。該方法可避免承載台之傾斜帶來之偏差，從而準確獲得圖案之圖像亮度之最大值與最小值，進而提高待測鏡頭之調製傳遞函數值測量精度。The method for measuring the modulation transfer function value of the lens provided by the technical solution corrects the tilt of the carrier relative to the test board before the test. Then test by moving the lens to be tested. The method can avoid the deviation caused by the tilt of the carrying platform, thereby accurately obtaining the maximum value and the minimum value of the image brightness of the pattern, thereby improving the measurement precision of the modulation transfer function value of the lens to be tested.
下面將結合附圖及複數實施例對本技術方案之測量鏡頭之調製傳遞函數值之方法作進一步詳細說明。The method for measuring the modulation transfer function value of the lens of the present technical solution will be further described in detail below with reference to the accompanying drawings and the embodiments.
本技術方案提供之測量鏡頭之調製傳遞函數值之方法可包括以下步驟：The method for measuring the modulation transfer function value of the lens provided by the technical solution may include the following steps:
第一步，提供鏡頭調製傳遞函數值測量裝置10與待測鏡頭100。所述鏡頭調製傳遞函數值測量裝置10包括測試板11、圖像感測器12、承載台13、處理器14、第一驅動器15與第二驅動器16，如圖1所示。In the first step, the lens modulation transfer function value measuring device 10 and the lens 100 to be tested are provided. The lens modulation transfer function value measuring device 10 includes a test board 11, an image sensor 12, a carrier 13, a processor 14, a first driver 15, and a second driver 16, as shown in FIG.
所述測試板11可為方形，其表面具有複數相對於測試板11之中心對稱之測試圖案，每一測試圖案均可包括複數間隔排布之條紋。如圖2所示，本技術方案實施例提供之測試板11為方形，其包括四個測試圖案，自所述測試板11之右上角開始順時針來看，分別為第一測試圖案110、第二測試圖案111、第三測試圖案112與第四測試圖案113。所述第一測試圖案110、第二測試圖案111、第三測試圖案112與第四測試圖案113各自包括三個間隔排布之暗條紋114。當然，所述暗條紋114之數量並不限於為三個。所述第一測試圖案110、第二測試圖案111、第三測試圖案112與第四測試圖案113分別靠近所述測試板11之一個頂角，且環繞所述測試板11之中心等角度分佈。如此，每當所述測試板11繞其中心旋轉90度後，每一測試圖案均與旋轉前與其相鄰之一個測試圖案重合，例如，將所述測試板11繞其中心順時針旋轉90度後，第一測試圖案110與旋轉前之第二測試圖案111重合，第二測試圖案111與旋轉前之第三測試圖案112重合。The test board 11 may be square, and its surface has a plurality of test patterns symmetric with respect to the center of the test board 11, and each of the test patterns may include a plurality of spaced strips. As shown in FIG. 2 , the test board 11 provided by the embodiment of the present technical solution is a square shape, and includes four test patterns. The first test pattern 110 and the first test pattern are respectively viewed from the upper right corner of the test board 11 . The second test pattern 111, the third test pattern 112, and the fourth test pattern 113. The first test pattern 110, the second test pattern 111, the third test pattern 112, and the fourth test pattern 113 each include three spaced apart dark stripes 114. Of course, the number of the dark stripes 114 is not limited to three. The first test pattern 110, the second test pattern 111, the third test pattern 112, and the fourth test pattern 113 are respectively adjacent to an apex angle of the test board 11 and are equiangularly distributed around the center of the test board 11. Thus, each time the test board 11 is rotated 90 degrees around its center, each test pattern coincides with a test pattern adjacent thereto before the rotation, for example, the test board 11 is rotated 90 degrees clockwise around its center. Thereafter, the first test pattern 110 coincides with the second test pattern 111 before the rotation, and the second test pattern 111 coincides with the third test pattern 112 before the rotation.
所述圖像感測器12與所述測試板11相對設置。所述圖像感測器12用於感測每個測試圖案經由待測鏡頭100所成像之亮度值。圖像感測器12可為電荷耦合圖像感測器或互補金屬氧化物半導體圖像感測器。The image sensor 12 is disposed opposite to the test board 11. The image sensor 12 is configured to sense a brightness value imaged by each test pattern via the lens 100 to be tested. Image sensor 12 can be a charge coupled image sensor or a complementary metal oxide semiconductor image sensor.
所述承載台13用於承載待測鏡頭100，其位於所述測試板11與圖像感測器12之間。The carrying platform 13 is configured to carry the lens 100 to be tested, and is located between the test board 11 and the image sensor 12 .
所述處理器14連接於所述圖像感測器12，用於接收所述圖像感測器12感測到之所述測試板11之測試圖案經待測鏡頭100所成像之亮度值並計算得到該成像之調製傳遞函數值。The processor 14 is connected to the image sensor 12 for receiving the brightness value of the test pattern of the test board 11 sensed by the image sensor 12 and being imaged by the lens 100 to be tested. The modulation transfer function value of the imaging is calculated.
所述第一驅動器15與所述圖像感測器12機械連接，用於驅動所述圖像感測器12相對於待測鏡頭100沿待測鏡頭100之光軸移動。所述第一驅動器15可為壓電元件或電機，其具有第一輸出軸150。所述第一輸出軸150機械連接於所述圖像感測器12。The first driver 15 is mechanically coupled to the image sensor 12 for driving the image sensor 12 to move along the optical axis of the lens 100 to be tested relative to the lens 100 to be tested. The first driver 15 can be a piezoelectric element or a motor having a first output shaft 150. The first output shaft 150 is mechanically coupled to the image sensor 12.
所述第二驅動器16與所述承載台13機械連接，用於驅動承載台13相對於測試板11沿垂直於測試板11所在之平面方向移動。所述第二驅動器16亦可為壓電元件或電機，其具有第二輸出軸160。所述第二輸出軸160機械連接於所述承載台13。The second driver 16 is mechanically coupled to the carrier 13 for driving the carrier 13 to move relative to the test board 11 in a direction perpendicular to the plane in which the test board 11 is located. The second driver 16 can also be a piezoelectric element or a motor having a second output shaft 160. The second output shaft 160 is mechanically coupled to the carrier table 13.
待測鏡頭100之焦距為F，其承載於所述承載台13。The focal length of the lens 100 to be tested is F, which is carried on the carrying platform 13.
第二步，使圖像感測器12相對於待測鏡頭100沿待測鏡頭100之光軸移動從而獲得待測鏡頭100對複數測試圖案以連續像距成像之連續調製傳遞函數值，並根據高斯公式獲得待測鏡頭100之物距與該調製傳遞函數值之連續關係曲線。In the second step, the image sensor 12 is moved along the optical axis of the lens 100 to be tested relative to the lens 100 to be tested to obtain a continuous modulation transfer function value of the plurality of test patterns of the to-be-tested lens 100 for continuous image distance imaging, and according to The Gaussian formula obtains a continuous relationship between the object distance of the lens 100 to be tested and the value of the modulation transfer function.
具體地，藉由第一驅動器15驅動所述圖像感測器12相對於待測鏡頭100沿待測鏡頭100之光軸移動，所述圖像感測器12感測與待測鏡頭100不同間距時（即待測鏡頭100不同像距V時）測試板11上之第一測試圖案110、第二測試圖案111、第三測試圖案112與第四測試圖案113經待測鏡頭100成像之亮度值。所述處理器14接收所述圖像感測器12感測到之待測鏡頭100對複數測試圖案以連續像距成像之連續調製傳遞函數值。待測鏡頭100之焦距為F，根據高斯成像公式1/U+1/V=1/F，將待測鏡頭100對複數測試圖案以連續像距成像之連續調製傳遞函數值之關係曲線換算成待測鏡頭100之物距與該調製傳遞函數值之連續關係曲線。例如，得到如圖3所示之曲線。Specifically, the image sensor 12 is driven to move along the optical axis of the lens 100 to be tested relative to the lens 100 to be tested by the first driver 15 , and the image sensor 12 senses different from the lens 100 to be tested. The brightness of the first test pattern 110, the second test pattern 111, the third test pattern 112, and the fourth test pattern 113 on the test board 11 through the lens to be tested 100 when the pitch is different (ie, when the lens 100 to be tested is different in image distance V) value. The processor 14 receives the continuous modulation transfer function value that the image sensor 12 senses by the image sensor 12 to image the complex test pattern in a continuous image distance. The focal length of the lens 100 to be tested is F, and according to the Gaussian imaging formula 1/U+1/V=1/F, the relationship between the to-be-tested lens 100 and the continuous modulation transfer function value of the continuous image pattern imaging of the complex test pattern is converted into A continuous relationship between the object distance of the lens 100 to be tested and the value of the modulation transfer function. For example, a curve as shown in FIG. 3 is obtained.
第三步，將待測鏡頭100繞自身光軸進行多次等角度旋轉從而獲得複數測試位置，每個測試位置時分別對與該測試位置相應之一個測試圖案成像，並獲得該成像之調製傳遞函數值。In the third step, the lens 100 to be tested is rotated at multiple equal angles around its optical axis to obtain a plurality of test positions, and each test position is respectively imaged with a test pattern corresponding to the test position, and the modulation transmission of the image is obtained. Function value.
待測鏡頭100之旋轉角度與相鄰兩個測試圖案旋轉後重合之角度相同，從而每個測試位置時複數測試圖案之分佈均相同。可理解，由於本實施例中，所述測試板11繞其中心旋轉90度後，每一測試圖案均與旋轉前與其相鄰之一個測試圖案重合，從而待測鏡頭100每旋轉90度到達一個測試位置，此時複數測試圖案之分佈與上一測試位置時複數測試圖案之分佈相同。The rotation angle of the lens 100 to be tested is the same as the angle at which the adjacent two test patterns are rotated, so that the distribution of the plurality of test patterns is the same at each test position. It can be understood that, in this embodiment, after the test board 11 is rotated 90 degrees around its center, each test pattern coincides with a test pattern adjacent thereto before the rotation, so that the lens 100 to be tested reaches 90 degrees per rotation. The test position is such that the distribution of the plurality of test patterns is the same as the distribution of the plurality of test patterns at the previous test position.
具體地，請參閱圖4，本實施例中，先將待測鏡頭100置於承載台13上，假設此時待測鏡頭100位於第一測試位置，其指示標記與所述第一測試圖案110對應，利用第一驅動器15帶動所述圖像感測器12相對於待測鏡頭100沿待測鏡頭100之光軸移動，所述處理器14藉由計算所述圖像感測器12感測到之測試板11上之第一測試圖案110經待測鏡頭100成像之亮度之最值得到所述第一測試圖案110對應之調製傳遞函數值為MTF1。本實施例中，將待測鏡頭100繞自身光軸進行旋轉前，還要於待測鏡頭100上作標記以指示之待測鏡頭100旋轉前後與承載台13之間之相對位置而判斷待測鏡頭100旋轉之角度。如，待測鏡頭100於第一測試位置時，所述標記指向第一測試圖案110所在頂角。當然，所述標記不一定設置於待測鏡頭100，還可設置於承載台13，僅需所作之標記可指示待測鏡頭100相對於承載台13旋轉之角度即可。Specifically, referring to FIG. 4 , in the embodiment, the lens 100 to be tested is first placed on the carrying platform 13 , and it is assumed that the lens 100 to be tested is located at the first test position, and the indication mark and the first test pattern 110 are Correspondingly, the image sensor 12 is moved along the optical axis of the lens 100 to be tested relative to the lens 100 to be tested by using the first driver 15 , and the processor 14 senses the image sensor 12 by calculating The first test pattern 110 on the test board 11 is subjected to the maximum value of the brightness of the image to be detected by the lens 100 to be measured, and the modulation transfer function value corresponding to the first test pattern 110 is obtained as MTF1. In this embodiment, before the lens 100 to be tested is rotated around its own optical axis, the lens to be tested 100 is further marked to indicate the relative position between the front and rear of the lens 100 to be tested and the stage 13 to be tested. The angle at which the lens 100 rotates. For example, when the lens 100 to be tested is in the first test position, the mark points to the top corner of the first test pattern 110. Of course, the mark is not necessarily disposed on the lens 100 to be tested, and may be disposed on the carrying platform 13 , and only needs to be marked to indicate the angle at which the lens 100 to be tested is rotated relative to the carrying platform 13 .
然後將待測鏡頭100從第一位置繞自身光軸順時針旋轉90度使其位於第二測試位置，此時待測鏡頭100之標記指向所述第二測試圖案111所在頂角，以相同之方法測得此時所述第二測試圖案111對應之調製傳遞函數值為MTF2。Then, the lens 100 to be tested is rotated 90 degrees clockwise from the first position around the optical axis thereof to be in the second test position, and the mark of the lens 100 to be tested is directed to the top corner of the second test pattern 111, which is the same. The method measures the modulation transfer function value corresponding to the second test pattern 111 at this time as MTF2.
再將待測鏡頭100從第二位置繞自身光軸順時針旋轉90度使其位於第三測試位置，此時待測鏡頭100上之標記指向所述第三測試圖案112所在頂角，測得此時所述第三測試圖案112對應之調製傳遞函數值為MTF3。Then, the lens 100 to be tested is rotated 90 degrees clockwise from the second position around the optical axis thereof to be in the third test position, and the mark on the lens 100 to be tested is directed to the apex angle of the third test pattern 112, and measured. At this time, the modulation transfer function value corresponding to the third test pattern 112 is MTF3.
最後待測鏡頭100從第三位置繞自身光軸順時針旋轉90度使其位於第四測試位置，此時待測鏡頭100之標記指向所述第四測試圖案113所在頂角，測得此時所述第四測試圖案113對應之調製傳遞函數值為MTF4。Finally, the lens 100 to be tested is rotated 90 degrees clockwise from the third position around the optical axis thereof to be in the fourth test position. At this time, the mark of the lens to be tested 100 points to the apex angle of the fourth test pattern 113, and the measurement is performed. The modulation transfer function value corresponding to the fourth test pattern 113 is MTF4.
第四步，於連續關係曲線上獲得與於該複數測試位置上獲得之調製傳遞函數值對應之複數物距值，並根據所述複數物距值調整承載台13以使承載台13與所述測試板11於複數測試圖案處之間距值相等。In the fourth step, a complex object distance value corresponding to the modulation transfer function value obtained at the complex test position is obtained on the continuous relationship curve, and the carrying platform 13 is adjusted according to the complex object distance value to make the carrying platform 13 and the The test board 11 has the same value between the complex test patterns.
具體地，於連續關係曲線上找出與第三步測得之第一測試圖案110之調製傳遞函數值MTF1對應之第一物距U1、第二測試圖案111之調製傳遞函數值MTF2對應之第二物距U2、第三測試圖案112之調製傳遞函數值MTF3對應之第三物距U3與第四測試圖案113之調製傳遞函數值MTF4對應之第四物距U4。所述第一物距U1即為所述測試板11於第一測試圖案110處與承載台13之間沿垂直於測試板11所在之平面方向之距離。所述第二物距U2即為所述測試板11於第二測試圖案111處與承載台13之間沿垂直於測試板11所在之平面方向之距離。所述第三物距U3即為所述測試板11於第三測試圖案112處與承載台13之間沿垂直於測試板11所在之平面方向之距離。所述第四物距U4即為所述測試板11於第四測試圖案113處與承載台13之間沿垂直於測試板11所在之平面方向之距離。根據第一物距U1、第二物距U2、第三物距U3與第四物距U4調整承載台13，如調整使得所述承載台13與測試板11分別於第一測試圖案110、第二測試圖案111、第三測試圖案112與第四測試圖案113處之間距大小均為U1，從而校正所述承載台13相對於測試板11之傾斜。Specifically, the first object distance U1 corresponding to the modulation transfer function value MTF1 of the first test pattern 110 measured in the third step and the modulation transfer function value MTF2 of the second test pattern 111 are respectively found on the continuous relationship curve. The second object distance U2, the third object distance M3 corresponding to the modulation transfer function value MTF3 of the third test pattern 112, and the fourth object distance U4 corresponding to the modulation transfer function value MTF4 of the fourth test pattern 113. The first object distance U1 is the distance between the test board 11 at the first test pattern 110 and the carrying platform 13 in a direction perpendicular to the plane of the test board 11. The second object distance U2 is the distance between the test board 11 at the second test pattern 111 and the carrying platform 13 in a direction perpendicular to the plane of the test board 11. The third object distance U3 is the distance between the test board 11 at the third test pattern 112 and the carrying platform 13 in a direction perpendicular to the plane in which the test board 11 is located. The fourth object distance U4 is the distance between the test board 11 at the fourth test pattern 113 and the carrying platform 13 in a direction perpendicular to the plane in which the test board 11 is located. Adjusting the carrying platform 13 according to the first object distance U1, the second object distance U2, the third object distance U3 and the fourth object distance U4, such as adjusting the loading table 13 and the test board 11 respectively in the first test pattern 110, The distance between the two test patterns 111, the third test pattern 112 and the fourth test pattern 113 is both U1, thereby correcting the tilt of the stage 13 relative to the test board 11.
第五步，驅動承載台13相對於所述測試板11沿待測鏡頭100之光軸移動，測試待測鏡頭100之準確調製傳遞函數值。In the fifth step, the driving stage 13 is moved along the optical axis of the lens 100 to be tested relative to the test board 11, and the accurate modulation transfer function value of the lens 100 to be tested is tested.
具體地，藉由第二驅動器16驅動承載台13相對於所述測試板11沿垂直於測試板11所在平面方向移動，設該移動過程中，圖像感測器12感測到測試板11上之第一測試圖案110、第二測試圖案111、第三測試圖案112與第四測試圖案113經待測鏡頭100成像之最大亮度值為Imax ，最小亮度值為Imin ，則待測鏡頭100之MTF值=(Imax -Imin )/(Imax +Imin )。Specifically, the second driver 16 drives the loading platform 13 to move relative to the test board 11 in a plane perpendicular to the plane of the test board 11. During the moving process, the image sensor 12 senses the test board 11. The first test pattern 110, the second test pattern 111, the third test pattern 112, and the fourth test pattern 113 are imaged by the lens 100 to be tested, and the maximum brightness value is I max , and the minimum brightness value is I min . The MTF value = (I max - I min ) / (I max + I min ).
本技術方案提供之測量鏡頭之調製傳遞函數值之方法於測試前校正承載台相對於測試板之傾斜。再藉由移動待測鏡頭進行測試。該方法可避免承載台之傾斜帶來之偏差，從而準確獲得圖案之圖像亮度之最大值與最小值，進而提高待測鏡頭之調製傳遞函數值測量精度。The method for measuring the modulation transfer function value of the lens provided by the technical solution corrects the tilt of the carrier relative to the test board before the test. Then test by moving the lens to be tested. The method can avoid the deviation caused by the tilt of the carrying platform, thereby accurately obtaining the maximum value and the minimum value of the image brightness of the pattern, thereby improving the measurement precision of the modulation transfer function value of the lens to be tested.
請參閱圖5，本技術方案第二實施例提供之調製傳遞函數值之測量方法與第一實施例之大致相同，其區別於於，本實施例中，所述測試板21僅包括兩個測試圖案，分別為第一測試圖案210與第二測試圖案211。所述第一測試圖案210與第二測試圖案211分別包括三個間隔排布之暗條紋214。所述第一測試圖案210與第二測試圖案211相對於所述測試板21之中心對稱。本實施例中，分別靠近所述測試板21相對之兩個側邊之一，且其上暗條紋214之延伸方向與其所靠近之側邊垂直。Referring to FIG. 5, the method for measuring the modulation transfer function value provided by the second embodiment of the present invention is substantially the same as that of the first embodiment, and is different from the test board 21 in the embodiment. The patterns are the first test pattern 210 and the second test pattern 211, respectively. The first test pattern 210 and the second test pattern 211 respectively include three spaced dark stripes 214. The first test pattern 210 and the second test pattern 211 are symmetrical with respect to a center of the test board 21 . In this embodiment, one of the two opposite sides of the test board 21 is adjacent to each other, and the direction in which the upper dark stripe 214 extends is perpendicular to the side to which it is adjacent.
由於測試圖案之數量及分佈方式不同，測試板21需旋轉180度，其上之複數測試圖案之形狀及分佈才可與上一位置重合。從而，於使本實施例之調製傳遞函數值之測量方法之第三步中，僅需測得待測鏡頭100旋轉0度與180度對應之調製傳遞函數值。於第四步中，僅需於待測鏡頭100之物距U與第一調製傳遞函數值之關係曲線上找到與0度與180度對應之調製傳遞函數值相應之第一物距與第二物距，調整承載台時，使所述承載台與所述測試板於第一測試圖案與第二測試圖案處之間距值均為第一物距或第二物距。如此，亦可實現校正所述承載台之傾斜。Due to the difference in the number and distribution of the test patterns, the test board 21 needs to be rotated by 180 degrees, and the shape and distribution of the plurality of test patterns thereon can coincide with the previous position. Therefore, in the third step of the method for measuring the value of the modulation transfer function of the present embodiment, only the modulation transfer function value corresponding to the rotation of the lens 100 to be tested by 0 degrees and 180 degrees is measured. In the fourth step, only the first object distance and the second corresponding to the modulation transfer function value corresponding to 0 degrees and 180 degrees are found on the relationship between the object distance U of the lens 100 to be tested and the value of the first modulation transfer function. And a distance between the first test pattern and the second test pattern of the test board and the test board is a first object distance or a second object distance. In this way, it is also possible to correct the tilt of the carrier.
當然，所述測試板上之測試圖案之數量並不限於為兩個或四個，還可以為三個、五個或更複數，僅需將測試板旋轉後，經由待測鏡頭之成像之複數測試圖案之位置與上一測試位置之成像相同。可理解，所述測試圖案越多，可使待測鏡頭旋轉至更多之位置從而得到更多之物距，對於承載台之傾斜可以校正之越精確。Of course, the number of test patterns on the test board is not limited to two or four, and may be three, five or more, and only after the test board is rotated, the plurality of images are imaged through the lens to be tested. The position of the test pattern is the same as the image of the previous test position. It can be understood that the more the test pattern, the more the position of the lens to be tested can be rotated to obtain more object distance, and the more accurate the tilt can be corrected for the tilt of the stage.
綜上所述，本發明確已符合發明專利之要件，遂依法提出專利申請。惟，以上所述者僅為本發明之較佳實施方式，自不能以此限制本案之申請專利範圍。舉凡熟悉本案技藝之人士援依本發明之精神所作之等效修飾或變化，皆應涵蓋於以下申請專利範圍內。In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.
10‧‧‧鏡頭調製傳遞函數值測量裝置
100‧‧‧待測鏡頭
11、21‧‧‧測試板
12‧‧‧圖像感測器
13‧‧‧驅動承載台
14‧‧‧處理器
15‧‧‧第一驅動器
16‧‧‧第二驅動器
150‧‧‧第一輸出軸
160‧‧‧第二輸出軸
110、210‧‧‧第一測試圖案
111、211‧‧‧第二測試圖案
112‧‧‧第三測試圖案
113‧‧‧第四測試圖案
114、214‧‧‧暗條紋
U1‧‧‧第一物距
U2‧‧‧第二物距
U3‧‧‧第三物距
U4‧‧‧第四物距
10‧‧‧Lens modulation transfer function value measuring device
100‧‧‧Densor to be tested
11, 21‧‧‧ test board
12‧‧‧Image Sensor
13‧‧‧Drive platform
14‧‧‧ Processor
15‧‧‧First drive
16‧‧‧Second drive
150‧‧‧First output shaft
160‧‧‧second output shaft
110, 210‧‧‧ first test pattern
111, 211‧‧‧ second test pattern
112‧‧‧ third test pattern
113‧‧‧ Fourth test pattern
114, 214‧‧‧ dark stripes
U1‧‧‧first object distance
U2‧‧‧Second object distance
U3‧‧‧third object distance
U4‧‧‧fourth distance
圖1係本技術方案第一實施例提供之調製傳遞函數值之測量裝置之結構示意圖。FIG. 1 is a schematic structural diagram of a device for measuring a modulation transfer function value provided by a first embodiment of the present technical solution.
圖2係本技術方案第一實施例提供之調製傳遞函數值之測量裝置中測試板之示意圖。2 is a schematic diagram of a test board in a measuring device for a modulation transfer function value provided by the first embodiment of the present technical solution.
圖3係本技術方案第一實施例提供之調製傳遞函數值之測量方法第二步所得之待測鏡頭之物距與該調製傳遞函數值之連續關係曲線。FIG. 3 is a continuous relationship between the object distance of the lens to be tested and the value of the modulation transfer function obtained by the second step of the method for measuring the modulation transfer function value provided by the first embodiment of the present technical solution.
圖4係本技術方案第一實施例提供之調製傳遞函數值之測量方法第三步狀態示意圖。FIG. 4 is a schematic diagram showing a third step state of a method for measuring a modulation transfer function value provided by the first embodiment of the present technical solution.
圖5係本技術方案第二實施例提供之調製傳遞函數值之測量裝置中測試板之示意圖。FIG. 5 is a schematic diagram of a test board in a measuring device for a modulation transfer function value provided by a second embodiment of the present technical solution.
10‧‧‧鏡頭調製傳遞函數值測量裝置 10‧‧‧Lens modulation transfer function value measuring device
100‧‧‧待測鏡頭 100‧‧‧Densor to be tested
11‧‧‧測試板 11‧‧‧Test board
12‧‧‧圖像感測器 12‧‧‧Image Sensor
13‧‧‧驅動承載台 13‧‧‧Drive platform
14‧‧‧處理器 14‧‧‧ Processor
15‧‧‧第一驅動器 15‧‧‧First drive
16‧‧‧第二驅動器 16‧‧‧Second drive
150‧‧‧第一輸出軸 150‧‧‧First output shaft
160‧‧‧第二輸出軸 160‧‧‧second output shaft
Claims (10)
提供測試板、圖像感測器、承載台、處理器與待測鏡頭，所述測試板具有複數相對於測試板之中心對稱之測試圖案，所述圖像感測器與所述測試板相對，用於感測測試圖案經由待測鏡頭之成像，所述承載台用於承載待測鏡頭，其位於所述測試板與圖像感測器之間，所述處理器連接於所述圖像感測器，用於處理並獲得圖像感測器感測到之成像之調製傳遞函數值；
使圖像感測器相對於待測鏡頭沿待測鏡頭之光軸移動從而獲得待測鏡頭對複數測試圖案以連續像距成像之連續調製傳遞函數值，並根據高斯公式獲得待測鏡頭之物距與該調製傳遞函數值之連續關係曲線；
將待測鏡頭繞自身光軸進行多次等角度旋轉從而獲得複數測試位置，每個測試位置時分別對與該測試位置相應之一個測試圖案成像，並獲得該成像之調製傳遞函數值；
於連續關係曲線上獲得與於該複數測試位置上獲得之複數調製傳遞函數值對應之複數物距值，並根據所述複數物距值調整承載台以使承載台與所述測試板於複數測試圖案處之間距值相等；
使承載台相對於所述測試板沿待測鏡頭之光軸移動以測試待測鏡頭之準確調製傳遞函數值。A method of measuring a lens modulation transfer function value, comprising the steps of:
Providing a test board, an image sensor, a carrier, a processor, and a lens to be tested, the test board having a plurality of test patterns symmetric with respect to a center of the test board, the image sensor being opposite to the test board For sensing the test pattern by imaging the lens to be tested, the carrier is for carrying a lens to be tested, which is located between the test board and the image sensor, and the processor is connected to the image a sensor for processing and obtaining a modulation transfer function value of the image sensed by the image sensor;
The image sensor is moved along the optical axis of the lens to be tested relative to the lens to be tested to obtain a continuous modulation transfer function value of the lens to be tested for continuous image distance imaging, and the object to be tested is obtained according to a Gaussian formula. a continuous relationship curve from the value of the modulation transfer function;
The lens to be tested is rotated a plurality of equal angles around its optical axis to obtain a plurality of test positions, and each test position is respectively imaged with a test pattern corresponding to the test position, and a modulation transfer function value of the image is obtained;
Obtaining a plurality of object distance values corresponding to the complex modulation transfer function values obtained at the complex test position on the continuous relationship curve, and adjusting the carrier according to the plurality of object distance values to enable the carrier and the test board to be tested in the plural The distance between the patterns is equal;
The carrier is moved relative to the test board along the optical axis of the lens to be tested to test the accurate modulation transfer function value of the lens to be tested.
提供測試板、圖像感測器、承載台、處理器與待測鏡頭，所述測試板具有相對於測試板之中心對稱之第一測試圖案與第二測試圖案，所述圖像感測器與所述測試板相對，用於感測每個測試圖案經由待測鏡頭之成像，所述承載台用於承載待測鏡頭，其位於所述測試板與圖像感測器之間，所述處理器連接於所述圖像感測器，用於處理並獲得圖像感測器感測到之成像之調製傳遞函數值；
使圖像感測器相對於待測鏡頭沿待測鏡頭之光軸移動從而獲得待測鏡頭對複數測試圖案以連續像距成像之連續調製傳遞函數值，並根據高斯公式獲得待測鏡頭之物距與該調製傳遞函數值之連續關係曲線；
將待測鏡頭繞自身光軸進行兩次等角度旋轉從而獲得第一測試位置與第二測試位置，分別獲得第一測試位置時對所述第一測試圖案成像對應之調製傳遞函數值與第二測試位置時對第二測試圖案成像對應之調製傳遞函數值；
於連續關係曲線上獲得與於該第一測試位置與第二測試位置上獲得之兩個調製傳遞函數值對應之第一物距與第二物距，並根據所述第一物距與第二物距調整承載台以使承載台與所述測試板於第一測試圖案與第二測試圖案處之間距值相等；
使承載台相對於所述測試板沿待測鏡頭之光軸移動以測試待測鏡頭之準確調製傳遞函數值。A method of measuring a lens modulation transfer function value, comprising the steps of:
Providing a test board, an image sensor, a carrier, a processor, and a lens to be tested, the test board having a first test pattern and a second test pattern symmetrical with respect to a center of the test board, the image sensor Opposite the test board, for sensing the imaging of each test pattern via a lens to be tested, the carrier is configured to carry a lens to be tested, which is located between the test board and the image sensor, a processor coupled to the image sensor for processing and obtaining a modulation transfer function value imaged by the image sensor;
The image sensor is moved along the optical axis of the lens to be tested relative to the lens to be tested to obtain a continuous modulation transfer function value of the lens to be tested for continuous image distance imaging, and the object to be tested is obtained according to a Gaussian formula. a continuous relationship curve from the value of the modulation transfer function;
The lens to be tested is rotated by two equal angles around its optical axis to obtain a first test position and a second test position, and the first test pattern is imaged corresponding to the modulation transfer function value and the second The second test pattern is imaged with a corresponding modulation transfer function value when the position is tested;
Obtaining a first object distance and a second object distance corresponding to the two modulation transfer function values obtained at the first test position and the second test position on the continuous relationship curve, and according to the first object distance and the second object distance Adjusting the carrying platform so that the distance between the loading platform and the test board between the first test pattern and the second test pattern is equal;
The carrier is moved relative to the test board along the optical axis of the lens to be tested to test the accurate modulation transfer function value of the lens to be tested.
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| CN104834177B (en) * | 2015-05-06 | 2017-04-26 | 福建省光学技术研究所 | Lens testing and calibration device |
| CN112985781B (en) * | 2021-04-27 | 2021-08-10 | 立臻科技(昆山)有限公司 | Lens test data processing method, device, equipment and storage medium |
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| US20070165131A1 (en) * | 2005-12-12 | 2007-07-19 | Ess Technology, Inc. | System and method for measuring tilt of a sensor die with respect to the optical axis of a lens in a camera module |
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| TW200925772A (en) * | 2007-12-14 | 2009-06-16 | Hon Hai Prec Ind Co Ltd | Method for measuring modulation transfer function value |
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| TW200509669A (en) * | 2003-08-25 | 2005-03-01 | Benq Corp | Method of judging relative position between optical sensing device and scan platform |
| US20070165131A1 (en) * | 2005-12-12 | 2007-07-19 | Ess Technology, Inc. | System and method for measuring tilt of a sensor die with respect to the optical axis of a lens in a camera module |
| JP2007315961A (en) * | 2006-05-26 | 2007-12-06 | Fujinon Corp | Lens-measuring device |
| TW200925772A (en) * | 2007-12-14 | 2009-06-16 | Hon Hai Prec Ind Co Ltd | Method for measuring modulation transfer function value |
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