外文翻譯---一種基于帶有特別的過濾和偏移調(diào)制的光柵投影的位移傳感器

1、<p><b>　　附 錄</b></p><p><b>　　附錄1</b></p><p>　　一種基于帶有特別的過濾和偏移調(diào)制的光柵投影的位移傳感器</p><p>　　胡建明，曾愛軍，王向朝，中國(guó)</p><p><b>　　摘要</b></p>

2、<p>　　由美國(guó)A-B公司生產(chǎn)的ControlLogix系列可編程序邏輯控制器(PLC)提供了多種接口類型：如以太網(wǎng)、ControlNet、DeviceNet、RS-232等等。ControlLogix以太網(wǎng)連接模塊“1756-ENET”使用了EtherNet/IP、ControlNet等協(xié)議，并采用了專業(yè)的服務(wù)代碼封裝于以太網(wǎng)協(xié)議包中。針對(duì)“實(shí)驗(yàn)性物理和工業(yè)控制系統(tǒng)”(EPICS)開發(fā)的驅(qū)動(dòng)程序使用了EtherNet/

3、IP協(xié)議，從而使得控制器可以運(yùn)行vxWorks RTOS、Win32和Unix/Linux的測(cè)試程序?，F(xiàn)在來分析一下這個(gè)接口的特點(diǎn)和使用場(chǎng)合。</p><p><b>　　1 正文</b></p><p>　　一種基于石油光柵空間濾波和偏振調(diào)制的位置傳感器被提出。它是一種光柵投射到被測(cè)物體上要通過4倍的空間濾波器光學(xué)系統(tǒng)。經(jīng)被測(cè)物體反射的光柵投影通過另一個(gè)4倍光學(xué)系統(tǒng)

4、成像形成莫爾條紋。莫爾極化信號(hào)獲取被測(cè)物體的位置信息。在位置傳感器，不同的莫爾正弦信號(hào)對(duì)應(yīng)不同的對(duì)象的位置。測(cè)量是用獨(dú)立的光柵投影強(qiáng)度和對(duì)象的反射率來衡量。在實(shí)驗(yàn)中，位置傳感器的效力得到證明，并且均方根（RMS）的每個(gè)測(cè)量位置誤差小于13納米。</p><p>　　位置的測(cè)量已在許多領(lǐng)域發(fā)揮了重要作用，例如制造，生物物理學(xué)，和自動(dòng)控制領(lǐng)域。在位置的測(cè)量方法，光學(xué)方法讓人更有興趣，因?yàn)樗哂懈叨鹊臏?zhǔn)確性并且是非接觸

5、式測(cè)量。在普通光學(xué)方法，諸如圖像測(cè)量，干涉儀，使用位置靈敏探測(cè)器（PDS）的直線位移測(cè)量，測(cè)量光束方向是垂直于被測(cè)物體表面的。當(dāng)有物體阻擋在對(duì)象的垂直方向時(shí)，普通光學(xué)方法就不在適用。要解決這個(gè)問題,本文提出一種新的基于臨界入射的位移光柵傳感器。</p><p>　　這種位置傳感器是如圖①-1所示。一個(gè)投射光柵被平行激光束照亮,投置到前面的焦面鏡L1。焦距透鏡組L1和L2組成4倍焦系統(tǒng)1。在這個(gè)4倍焦系統(tǒng)中，頻率平

6、面有一個(gè)孔徑。投影光柵被投射到被測(cè)物體投影光柵通過這個(gè)臨界入射的4倍焦系統(tǒng)1 被檢測(cè)。由鏡頭L3和L4組成的4倍焦系統(tǒng)2同系統(tǒng)1有相同的光學(xué)參數(shù)。這個(gè)傳感光柵呈現(xiàn)在L4的背面焦點(diǎn)平面。經(jīng)物體反射后,這個(gè)投影光柵的影像通過4倍焦系統(tǒng)2 投影到傳感光柵上。由于檢測(cè)光柵和投影光柵的影像重疊產(chǎn)生莫爾條紋。莫爾條紋輸出信號(hào)隨物體的方位變化由一個(gè)探測(cè)器通過透鏡L5探測(cè)到。一個(gè)起偏鏡和鍍板在L4和檢測(cè)光柵之間。形成投影光柵圖像的光線通過偏光系統(tǒng)成為線

7、性偏振光。通過鍍板，線性偏振光被分成兩個(gè)垂直極化相互交叉的光線。一個(gè)分析儀安置在檢測(cè)光柵和L5之間。當(dāng)分析儀是圍繞在4倍焦系統(tǒng)2的光軸線周圍，偏光器板和分析形成偏振調(diào)制器。隨著極化調(diào)制，莫爾信號(hào)對(duì)在光柵投影上光的強(qiáng)度的變化是不敏感的。因此，該被測(cè)物體的位置，通過檢測(cè)調(diào)制能夠準(zhǔn)確的測(cè)量。</p><p>　　圖①-1位置傳感器示意圖</p><p>　　在圖①-1中，位于4倍焦系統(tǒng)中的光軸定

8、義為z軸。投影光柵平面上,垂直、平行于投影光柵槽的方向分別被定義為x0和y0軸。同樣，定義x2，y2軸和x3，y3軸。在4倍焦系統(tǒng)1的頻平面上的x1，y1軸分別平行于光柵投影平面x0，y0軸。光柵投影中心放置在x0軸的起點(diǎn)。該光柵投影空間的比例為1:1。光柵投影的周期和寬度分別為D和B。通過光柵投影振幅分布表示為：</p><p><b>　?。á?1）</b></p><

9、;p>　　公式（①-1）中I1是在光柵投影強(qiáng)度。隨著透鏡L1傅立葉變換，在4焦距系統(tǒng)的頻平面上的頻率分布情況為：</p><p><b>　?。á?2）</b></p><p>　　式中λ是激光波長(zhǎng)和f是L1的焦距。在頻平面上，孔徑作為空間濾波器，其過濾的功能如下所示：</p><p><b>　　（①-3）</b>

10、</p><p>　　因此，只有0，± 1衍射角的光能通過孔徑，通過孔徑的頻率分布寫為：</p><p><b>　?。á?4）</b></p><p>　　經(jīng)L2傅里葉變換，在L2的回焦平面上振幅E(x2) 分布如下式：</p><p><b>　　（①-5）</b></p>

11、<p>　　因此，在光柵投影圖像的光強(qiáng)分布表示為：</p><p><b>　　（①-6）</b></p><p>　　被測(cè)物放在靠近L2 的背焦點(diǎn)的地方。L3的前焦點(diǎn)與L2的背焦點(diǎn)是重疊，4倍焦系統(tǒng)的1和2在縱向是對(duì)稱的。經(jīng)過對(duì)象反射，投影通過4倍焦系統(tǒng)成像與檢測(cè)光柵上。L3的前焦點(diǎn)所在水平面被定義為位移傳感器的零平面。如果在被測(cè)物與傳感器的零平面之間

12、存在一距離x，檢測(cè)光柵投影光柵在檢測(cè)光柵上的圖像將隨著位置的改變而變化：</p><p><b>　?。á?7）</b></p><p>　　式中θ是入射光角度。關(guān)于檢測(cè)光柵投影光柵在檢測(cè)光柵上的圖像的光強(qiáng)分布表示為：</p><p><b>　　（①-8）</b></p><p>　　式中R表示被

13、測(cè)物的反射率。起偏器的傳播軸線與檢測(cè)光柵槽間的夾角為45 °。鍍板包括兩塊相互正交的雙折射板。它將形成投影光柵的圖像光線分成正交極化、相互交叉的兩條線，即常規(guī)的和特殊的光射線。因此，投影光柵的被稱作常和特殊的兩個(gè)圖像在檢測(cè)光柵上成像。兩圖像間的距離是d/2。常規(guī)和特殊的圖像強(qiáng)度分布表示為：</p><p><b>　?。á?9）</b></p><p>&l

14、t;b>　　（①-10）</b></p><p>　　兩式中，－B/2≤x3－2x sinθ≤B/2。檢測(cè)光柵有同投影光柵一樣的周期和占空比，而且有平行的槽。檢測(cè)光柵放在距離軸X3的起點(diǎn)d/4的地方。兩個(gè)莫爾信號(hào)表示如下：</p><p><b>　　（①-11）</b></p><p><b>　?。á?12）&l

15、t;/b></p><p>　　如果檢偏鏡透線與檢測(cè)光柵槽間的角度是α，那么這兩個(gè)通過檢偏鏡的莫爾信號(hào)表示如下：</p><p><b>　　，（①-13）</b></p><p><b>　　（①-14）</b></p><p>　　檢測(cè)器通過檢偏鏡檢測(cè)光通量，探測(cè)器上的光強(qiáng)度由下式給出：&

16、lt;/p><p><b>　?。á?15）</b></p><p>　　當(dāng)檢偏鏡繞4倍焦系統(tǒng)2的光軸轉(zhuǎn)動(dòng)角度為α?xí)r，莫爾信號(hào)的極化調(diào)制得以實(shí)現(xiàn)，它在檢測(cè)器上表示為：</p><p><b>　?。á?16）</b></p><p>　　此時(shí)，光強(qiáng)度信號(hào)被檢測(cè)器轉(zhuǎn)化為包含直流分量IDC和交變電流分量IA

17、C的電信號(hào)。電力信號(hào)由放大器放大，其直流和交流成分被濾波電路分開。被測(cè)物的位移表示如下：</p><p><b>　　（①-17）</b></p><p><b>　　x的范圍：</b></p><p><b>　?。á?18）</b></p><p>　　在(17)中，IAC

18、和IDC有相同的因子I1和R，因此，位移x與初始強(qiáng)度I1和反射率R無關(guān)。那么，激光輸出強(qiáng)度和不同被測(cè)物的反射率將不會(huì)影響位移傳感器。</p><p>　　按光路圖①-1所示，進(jìn)行了實(shí)驗(yàn)。用一束波長(zhǎng)為785nm的平行激光照射投影光柵。投影光柵的周長(zhǎng)為0.1mm，占空比為1:1。透鏡L1的焦距為120 mm。4倍焦系統(tǒng)1的頻率板上的孔徑為3.5 mm。被測(cè)物放在一個(gè)能提供做上下線性運(yùn)動(dòng)的地方。4倍焦系統(tǒng)1的光軸線與正

19、規(guī)物體間的夾角為84.5°。4倍焦系統(tǒng)2和4倍焦系統(tǒng)1有相同的光學(xué)參數(shù)，檢測(cè)光柵和投影光柵有相同的光學(xué)參數(shù)。起偏器和檢偏器是格倫泰勒棱鏡。鍍板由兩個(gè)相同的光束位移差0.05 mm的石英棱鏡組成。檢偏鏡放置在一移動(dòng)的裝置上，通過旋轉(zhuǎn)調(diào)制莫爾信號(hào)。</p><p>　　圖①-2 當(dāng)垂直移動(dòng)對(duì)象時(shí)IAC/IDC（a）和均方根誤差（b）測(cè)量結(jié)果</p><p>　　試驗(yàn)中，通過移動(dòng)裝

20、置在50um的范圍內(nèi)按2.5um的步進(jìn)一步步移動(dòng)被測(cè)物。在每個(gè)位置對(duì)被測(cè)物高度測(cè)量100次。實(shí)驗(yàn)結(jié)果顯示在圖①-2。圖①-2(a)顯示IAC／IDC與被測(cè)物高度的關(guān)系。IAC／IDC隨高度做正弦變化。至此，該位置傳感器測(cè)量原理得以驗(yàn)證。圖①-2（b）顯示了均方根（RMS）21位置測(cè)量誤差的均方根（RMS），其值小于13 nm。因此，被測(cè)物象的高度被位移傳感器高精度測(cè)量。最后，我們提出了一種基于帶有特別的過濾和偏移調(diào)制的光柵投影的位移傳感

21、器。這種位移傳感器適用于垂直被測(cè)物方向有障礙物的測(cè)量。莫爾信號(hào)隨物體位移變化而產(chǎn)生的正弦曲線由位移傳感器得到。這種位置傳感器是基于不敏感的光源和物體極化調(diào)制反射率的差異而在輸出發(fā)生變化。試驗(yàn)中，該方法的可行性得以驗(yàn)證。</p><p><b>　　附錄2</b></p><p>　　A position sensor based on grating projecti

22、on with spatial filtering and polarization modulation</p><p>　　Jianmlng Hu(胡建明)12，Aijun Zeng(曾愛軍)1，and Xiangzhao Wang(王向朝)</p><p>　　Shanghai Institute of Optics and Fine Mechanics，Chinese Academ

23、y of Sciences，Shanghai 201800 Graduate School of the Chinese Academy of Sciences, Beijing 100039</p><p>　　Received April 26．2005</p><p>　　A position sensor based oil grating projection with spat

24、ial filtering and polarization modulation is presented．A grating is projected onto the object to be measured through a 4f optical system with a spatial filter．After reflected by the object the grating projection is image

25、d on a detection grating through another 4f optical system to form moiré fringes. The polarization modulated moire signal is detected to obtain the position information of the object．In the position sensor，the moire

26、 signal v</p><p>　　Position measurements have been playing an important role in many fields such as fabrication, biophysics, and auto control．In methods of position measurement，optical method holds more inte

27、rest because of its high accuracy and non-contact measurement. In the common optical methods such as image measurement, interferometer ,and direct position detection using position sensitive detector (PDS),the measuring

28、beam is in the direction perpendicular to the surface of the object to be measured. When the</p><p>　　The position sensor is schematically shown in Fig. ②-1.A proiection grating is illuminated by a collimate

29、d laser beam and placed in the front focal plane of lens L1．Lenses L1 and L2 form 4f system 1．In this 4f system，an aperture is placed in the frequency plane．The projection grating is projected onto the object to be meas

30、ured through the 4f system 1 with grazing incidence．The 4f system 2 composed of lenses L3 and L4 Jams the same optical parameters with 4f system 1．The detection grating is pla</p><p>　　Fig. ②-1.Schematic dia

31、gram of the position sensor</p><p>　　In Fig ②-1．the optical axes of the 4f systems are defined as z axis．In the projection grating plane，the directions perpendicular and parallel to the groove of the project

32、ion grating are defined as directions of x0 mid y0 axes respectively．Similarly, x2 ,y2 axes and x3，y3 axes are defined on the image planes of the projection grating．In the frequency plane of the 4f system 1，x1，y1 axes ar

33、e parallel to x0, y0 axes in the projection grating plane，respectively．The center of the projection grating is</p><p><b>　?。á?1）</b></p><p>　　Where I1 is the intensity on the project

34、ion grating．With Fourier transform of lens L1, the frequency distribution in the frequency plane of the 4f system 1 is given as</p><p><b>　?。á?2）</b></p><p>　　where λ is the waveleng

35、th of the laser and f is the focal length of L1．In the frequency plane，the aperture is used as a spatial filter and its filtering function is written as</p><p><b>　　（②-3）</b></p><p>

36、　　Hence only 0, ±1 diffraction orders pass the aperture and the frequency distribution through the aperture is written as</p><p><b>　　（②-4）</b></p><p>　　With Fourier transform o

37、f L2，the amplitude distribution E(x2) in the back focal plane of L2 is given by</p><p><b>　?。á?5）</b></p><p>　　Thus the intensity distribution I(x2) of the image of projection gratin

38、g is expressed as</p><p><b>　?。á?6）</b></p><p>　　The object to be measured is placed near the back focus of L2．The front focus of L3 is superposed with the back focus of L2 and 4f sy

39、stems 1 and 2 are laid symmetrically relative to tile vertical. After reflected by the object，the projection is imaged on the detection grating through the 4f system 2．The horizontal plane where the front focus of L3 is

40、 placed is defined as the zero plane of the position sensor．If there exists a distance x between the object and the sensor’s zero plane, the image </p><p><b>　?。á?7）</b></p><p>　　whe

41、reθis the angle of grazing incidence．The intensity distribution of the image of the projection grating on the detection grating is expressed as</p><p>　?。á?8） where R is the reflectivity of the object to be

42、 measured. The angle between the polarizer’s transmission axis and the groove direction of the detection grating is 45°．The Savant plate comprises two birefringence plates whose optic axes are orthogonal mutually．It

43、 splits the rays that form the image of the projection grating into two orthogonally polarized and mutually sheared rays，namely ordinary and extraordinary rays. Thus two images of the projection grating called ordinary a

44、nd extraord</p><p>　　（②-9） （②-10）</p><p>　　respectively，where －B／2≤x3－2x sinθ≤B／2．The detection grating has the same period and line-to-space ratio as the projection grating and its groove

45、is parallel to the groove of the projection grating．The detection grating is placed with d／4 offset relative to the origin of axis x3．The two moiré signals are written as</p><p><b>　?。á?11）</b&

46、gt;</p><p><b>　?。á?12）</b></p><p>　　If the angle between the analyzer’s transmission axis and groove direction of the detection grating is α，the two moiré signals through the an

47、alyzer are written as</p><p><b>　?。á?13）</b></p><p><b>　?。á?14）</b></p><p>　　The detector detects the light flux through the analyzer，and the intensity on th

48、e detector is given by</p><p><b>　?。á?15）</b></p><p>　　When the analyzer is rotated with angle α(t) around the optical axis of the 4f system 2，polarization modulation of the moir

49、3; signal is realize and the modulated intensity on the detector is expressed as</p><p><b>　?。á?16）</b></p><p>　　The intensity is converted by the detector into electric signal which

50、 includes a direct current component IDC and an alternating current component IAC．The electric signal is amplified by an amplifier and its direct and alternating current components are separated by a filter circuit．The p

51、osition of the object is given by</p><p><b>　?。á?17）</b></p><p>　　with the variation range</p><p><b>　?。á?18）</b></p><p>　　In Eq(17)，IAC and IDC

52、 have common factors I1 and R，so the distance is independent of the initial intensity I1 and the reflectivity R．The influence of the output variation of the laser and the reflectivity difference in different objects to b

53、e measured can be eliminated in the position sensor．</p><p>　　Using the light path shown in Fig. ②-1, the experiment was carried out．A projection grating was illuminated by a collimated laser beam whose wave

54、length was 785nm．The period of projection grating was 0.1 mm．The fine-to-space ratio of projection grating is 1：1．The focal length of lens L1 was 120 mm．The diameter of the aperture in the frequency plane of the 4f syste

55、m 1 was 3.5 mm. The object to be measured was placed on a manual linear stage supplying up／down movement．The angle between the axis of </p><p>　　Fig ②-2．IAC／IDC (a) and RMS error(b)measurement results when v

56、ertically moving the object．</p><p>　　In the experiment，the position of the object was changed by moving the manual linear stage step by step with 2.5-um step size within 50-um range．At each position，the he

57、ight of the object was measured 100 times．The experiment results are shown in Fig. ②-2．Figure②- 2(a) shows the relation between the IAC／IDC and the height of the object．IAC／IDC varies sinusoidally with the height．Therefo