Volume 52 Issue 3
Mar.  2023
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Huang Yuetian, Fan Bin, Li Shijie, Liang Haifeng, Cai Changlong, Liu Weiguo. Error control of diffractive optical element fabricated by single point diamond turning[J]. Infrared and Laser Engineering, 2023, 52(3): 20220504. doi: 10.3788/IRLA20220504
Citation: Huang Yuetian, Fan Bin, Li Shijie, Liang Haifeng, Cai Changlong, Liu Weiguo. Error control of diffractive optical element fabricated by single point diamond turning[J]. Infrared and Laser Engineering, 2023, 52(3): 20220504. doi: 10.3788/IRLA20220504

Error control of diffractive optical element fabricated by single point diamond turning

doi: 10.3788/IRLA20220504
Funds:  Science and Technology Department of Shaanxi Province (2022GY-222); Industrial Chain Project of Shaanxi Science and Technology Department (2021ZDGY12-05)
  • Received Date: 2022-07-21
  • Rev Recd Date: 2022-10-09
  • Publish Date: 2023-03-25
  •   Objective   Diffractive optical elements are more and more widely used in infrared optical system, which requires higher processing quality of diffractive structure. High-precision diffractive microstructure surface can be machined directly by single point diamond turning. However, the position error and surface quality of diffraction structure have great influence on its optical properties. The diffraction efficiency of diffractive optical element is mainly affected by surface profile quality and surface roughness. The surface profile error and roughness error will produce shadow and scattering effect, which will reduce the diffraction efficiency of diffractive optical element. In order to improve the performance of diffractive optical components, there have been many researches on improving the turning quality of diffractive optical components, but the influence of the surface morphology of the diffraction plane has been ignored. In order to improve the performance of diffractive optical elements, it is necessary to control their turning errors accurately.  Methods   The factors affecting the surface quality of the diffraction element in the process of SPDT processing were analyzed. On this basis, a mathematical model among the ring position error, diffraction surface shape and tool radius was established (Fig.1), which was used to simulate and calculate the relationship between the size of the machining residue area and the turning surface roughness and tool radius. The selection of machining parameters of diffraction optical element turning is guided. Combined with the simulation model and roughness influence parameters, the selection of turning tool radius is guided. It provides technical support for obtaining the high-precision surface topography of diffractive optical elements and is beneficial to improve the imaging quality of diffractive optical elements. Then, based on the simulation results, the machining capability of SPDT on the diffraction surface and the validity of the simulation model are verified by experiments, so as to provide technical support for the high-precision mass production of diffraction optical components.  Results and Discussions   Finally, based on the simulation results, a semi arc tool with a radius of 0.02 mm is selected for machining. The shape error of diffraction element is 292 nm (Fig.6), the maximum position error of diffraction band is 55 nm, the maximum height error is 16 nm (Fig.7), and the roughness is 5.6 nm (Fig.9). Experimental results indicate that the prediction model can guide the acquisition of high precision surface topography of diffractive optical elements, which is beneficial to improve the imaging quality of the optical system. The research results provide technical support for the development of high-precision diffractive optical elements and have a wide range of engineering applications.  Conclusions   Based on the error analysis of single point diamond turning processing diffraction structure, the diffraction element machined by semicircular arc tool has higher machining accuracy and position accuracy. Before the diffraction element is processed, the proper tool radius is selected by using the simulation model of the position error of the annular band of the diffraction structure with a semicircular tool combined with the influence factors of surface roughness. High-precision diffractive optical element can be obtained by controlling the shape of the base plane. According to the design of the diffraction structure plane shape and simulation model, the semi-circular diamond tool with the tool radius of 0.02 mm was selected for turning. The surface shape error of the diffraction element was 292 nm, the position error of the diffraction ring was less than 55 nm, the height error was less than 16 nm, and the roughness was 5.6 nm. The experimental results show that the prediction model can guide the acquisition of high-precision surface topography of diffractive optical elements and improve the imaging quality of diffractive optical elements. The results provide technical support for the development of high-precision diffractive optical elements and have a wide range of engineering applications.
  • [1] Wang Yefei, Cheng Yanping, Yao Yuan, et al. Design of membrane diffractive athermal infrared optical system [J]. Infrared Technology, 2021, 43(5): 422-428. (in Chinese)
    [2] Zhang Fang, Zhu Jing, Song Qiang, et al. Reducing aberration effect of Fourier transform lens by modifying Fourier spectrum of diffractive optical element in beam shaping optical system [J]. Applied Optics, 2015, 54(30): 8891-8898. (in Chinese)
    [3] Fan Bin, Liu Yanli, Zhao Haibo, et al. A new deep space hyperspectral diffraction computational imaging detection technology (Invited) [J]. Infrared and Laser Engineering, 2020, 49(5): 20201005. (in Chinese)
    [4] Wang Daodang, Xie Zhongmin, Wang Chao, et al. Probe misalignment calibration in fiber point-diffraction interferometer [J]. Opt Express, 2019, 27(23): 34312-34322. doi:  10.1364/OE.27.034312
    [5] Zhu Qixing, Wang Daodang, Lu Yiwei, et al. Optimization and error correction of dual-path fiber point-diffraction interference projection system [J]. Infrared and Laser Engineering, 2022, 51(3): 20210140. (in Chinese)
    [6] Zhi X, Jiang S, Zhang W, et al. Image degradation characteristics and restoration based on regularization for diffractive imaging [J]. Infrared Physics & Technology, 2017, 86: 226-238.
    [7] Wang S W, Lai J C, Li Z J, et al. Design and implementation of a linear array laser emitting optical system based on diffractive principles [J]. Optik, 2020, 224(6): 165693.
    [8] Bourgade A, Meur J L, Pigeon Y E, et al. Analysis of various approaches for the fabrication of diffractive optical elements [C]//Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference, 2019.
    [9] Jonušauskas L, Gailevičius D, Rekštytė S, et al. Mesoscale laser 3D printing [J]. Optics Express, 2019, 27(11): 15205-15221. doi:  10.1364/OE.27.015205
    [10] Ruffato G, Massari M, Romanato F. Diffractive optics for combined spatial- and mode- division demultiplexing of optical vortices: Design, fabrication and optical characterization [J]. Sci Rep, 2016, 6(1): 24760.
    [11] Khoury M E, Winterstein T, Weber W, et al. Photolithographic fabrication of micro apertures in dry film polymer sheets for channel recordings in planar lipid bilayers [J]. The Journal of Membrane Biology, 2019, 252(2-3): 173-182.
    [12] Wang Lun, Xue Changxi, Lan Xirui, et al. Manufacturing technology of diffractive optical elements formed by ultraviolet-cured organic-inorganic nanocomposites [J]. Acta Optica Sinica, 2019, 39(7): 0722001. (in Chinese)
    [13] Ouyang Xu, Xu Yi, Feng Ziwei, et al. Polychromatic and polarized multilevel optical data storage [J]. Nanoscale, 2019, 11(5): 2447-2452.
    [14] Timo Gissibl, Simon Thiele, Alois Herkommer, et al. Two-photon direct laser writing of ultracompact multi-lens objectives [J]. Nature Photonics, 2016, 10(8): 554-560.
    [15] Hoeflich K, Jurczyk J, Zhang Y, et al. Direct electron beam writing of silver-based nanostructures [J]. ACS Applied Materials & Interfaces, 2017, 9(28): 24071-24077.
    [16] Wang Peng, Xue Dongbai, Zhang Hao, et al. ESCV cutting method during infrared crystal single point diamond turning process [J]. Infrared and Laser Engineering, 2019, 48(7): 0742001. (in Chinese) doi:  10.3788/IRLA201948.0742001
    [17] Zhang Yunlong, Wang Zhibin, Zhang Feng, et al. Detection and data processing of diffractive optical element [J]. Journal of Applied Optics, 2018, 39(3): 355-358.
    [18] Zhang Feng, Wang Zhibin, Zhang Yunlong, et al. Diamond turning compensation techniques of diffractive optical elements [J]. Journal of Applied Optics, 2014, 35(6): 1058-1062. (in Chinese)
    [19] Zhang Yunlong, Wang Zhibin, Zhang Feng, et al. Detection and data processing of diffractive optical element [J]. Journal of Applied Optics, 2018, 39(3): 355-358. (in Chinese)
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Error control of diffractive optical element fabricated by single point diamond turning

doi: 10.3788/IRLA20220504
  • 1. Key Laboratory of Thin Film Technology and Optical Inspection of Shaanxi Province, School of Opto-electronic Engineering, Xi 'an Technological University, Xi 'an 710021, China
  • 2. Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China
Fund Project:  Science and Technology Department of Shaanxi Province (2022GY-222); Industrial Chain Project of Shaanxi Science and Technology Department (2021ZDGY12-05)

Abstract:   Objective   Diffractive optical elements are more and more widely used in infrared optical system, which requires higher processing quality of diffractive structure. High-precision diffractive microstructure surface can be machined directly by single point diamond turning. However, the position error and surface quality of diffraction structure have great influence on its optical properties. The diffraction efficiency of diffractive optical element is mainly affected by surface profile quality and surface roughness. The surface profile error and roughness error will produce shadow and scattering effect, which will reduce the diffraction efficiency of diffractive optical element. In order to improve the performance of diffractive optical components, there have been many researches on improving the turning quality of diffractive optical components, but the influence of the surface morphology of the diffraction plane has been ignored. In order to improve the performance of diffractive optical elements, it is necessary to control their turning errors accurately.  Methods   The factors affecting the surface quality of the diffraction element in the process of SPDT processing were analyzed. On this basis, a mathematical model among the ring position error, diffraction surface shape and tool radius was established (Fig.1), which was used to simulate and calculate the relationship between the size of the machining residue area and the turning surface roughness and tool radius. The selection of machining parameters of diffraction optical element turning is guided. Combined with the simulation model and roughness influence parameters, the selection of turning tool radius is guided. It provides technical support for obtaining the high-precision surface topography of diffractive optical elements and is beneficial to improve the imaging quality of diffractive optical elements. Then, based on the simulation results, the machining capability of SPDT on the diffraction surface and the validity of the simulation model are verified by experiments, so as to provide technical support for the high-precision mass production of diffraction optical components.  Results and Discussions   Finally, based on the simulation results, a semi arc tool with a radius of 0.02 mm is selected for machining. The shape error of diffraction element is 292 nm (Fig.6), the maximum position error of diffraction band is 55 nm, the maximum height error is 16 nm (Fig.7), and the roughness is 5.6 nm (Fig.9). Experimental results indicate that the prediction model can guide the acquisition of high precision surface topography of diffractive optical elements, which is beneficial to improve the imaging quality of the optical system. The research results provide technical support for the development of high-precision diffractive optical elements and have a wide range of engineering applications.  Conclusions   Based on the error analysis of single point diamond turning processing diffraction structure, the diffraction element machined by semicircular arc tool has higher machining accuracy and position accuracy. Before the diffraction element is processed, the proper tool radius is selected by using the simulation model of the position error of the annular band of the diffraction structure with a semicircular tool combined with the influence factors of surface roughness. High-precision diffractive optical element can be obtained by controlling the shape of the base plane. According to the design of the diffraction structure plane shape and simulation model, the semi-circular diamond tool with the tool radius of 0.02 mm was selected for turning. The surface shape error of the diffraction element was 292 nm, the position error of the diffraction ring was less than 55 nm, the height error was less than 16 nm, and the roughness was 5.6 nm. The experimental results show that the prediction model can guide the acquisition of high-precision surface topography of diffractive optical elements and improve the imaging quality of diffractive optical elements. The results provide technical support for the development of high-precision diffractive optical elements and have a wide range of engineering applications.

    • 与非球面透镜相比,衍射光学元件更适用于小视场、大孔径光学系统,具有非球面透镜的功能,但其结构更为简化[1-3]。同时,衍射光学元件的出现进一步简化了光学系统。衍射光学元件的应用涉及多个行业和科研领域,如太阳能光伏仪器制造工艺、激光探测系统、红外探测被动运动探测器、智能家居安防系统探头等都有实际应用[4-6]

      衍射光学元件可以通过一系列光刻工艺或直接写入技术制造,如激光束写入、单点金刚石车削或电子束写入[7-11]。早期的衍射光学元件制造方法是采用大规模集成电路制造技术,由于采用二元光学方法,连续的衍射曲面被阶梯形逼近,在此基础上提出了用电子束或激光束直写技术加工连续衍射曲面的方法。然而光刻法加工的微结构尺寸一般在亚微米尺度上,同时还受到光学衍射的限制。与光学光刻相比,电子束直写具有更高的分辨率。但是电子束直写不仅效率低,而且受限于适用材料的范围。激光加工技术对薄膜材料的普适性和加工效率提出了很大的困难和挑战[12-15]。近年来,通过单点金刚石车削技术加工红外衍射光学元件已经十分成熟。随着设备和技术的提升,利用SPDT技术制造衍射光学元件模具,再通过复刻技术,实现批量生产[16-17]。考虑到加工成本和效率,特别是对于渐进式光学微结构,SPDT技术是一种经济高效的选择。

      衍射光学元件的衍射效率主要受表面轮廓质量和表面粗糙度影响。表面轮廓误差和粗糙度误差会产生阴影和散射效应,从而降低衍射光学元件的衍射效率。为了提高衍射光学元件的性能,对于衍射元件车削质量提升的相关研究已有很多,但都忽略了衍射面的面形形貌影响[18-19]。基于此,文中对SPDT技术加工过程中影响衍射元件表面质量的因素进行了分析,在此基础上,建立了环带位置误差、衍射面面形和刀具半径三者之间的数学模型,用来仿真计算加工残留区域的大小;结合车削表面粗糙度与刀具半径关系,指导衍射光学元件车削加工参数的选取。为衍射光学元件高精度表面形貌的获取提供了一定的技术支持,有利于提高衍射光学元件的成像质量。

    • 车削后的衍射光学元件的评价指标主要包括衍射面面形质量、环带位置误差和表面粗糙度等。表面轮廓误差和粗糙度误差会产生阴影和散射效应,车削残留区域会使入射光线偏离理想的传播方向,造成遮挡效应,这些误差会降低衍射效率和系统透过率,从而降低光学系统成像质量。

      表面粗糙度主要与加工参数有关,包括主轴转速、进给速度和刀具半径等,通过正交实验可以得到合适的加工参数。其经验公式如下:

      式中:f为每转进给量;R为刀具半径。

      而面形质量受主轴运动误差、刀具波纹度误差和环境振动等因素的影响。对于衍射光学元件来说,衍射环带的位置决定了衍射波前的形状,衍射环带的台阶高度对衍射效率有重要影响。因此,需要对衍射环带的宽、高误差进行高精度控制。

      对于渐变锯齿形衍射面的加工,选择适合的刀具是非常重要的。由于刀具半径不能为零,在锯齿衍射结构底部总会存在一些小的加工盲区,如图1所示,该残留区域会造成一定的遮挡效应。残留区域不仅影响光学系统的像质,而且降低了衍射效率,导致透射率损失。残留区域的大小与刀具半径和衍射面形状有关,其中宽度D和高度H是主要的环带位置误差。

      Figure 1.  Schematic diagram of residual area of diffraction structure turning

      车削残留区域会使入射光线偏离理想的传播方向,造成遮挡效应,降低衍射效率和系统透过率,透过率的损失可以由下式计算:

      式中:r为工作区域半径;$ {r}_{i} $为第i个衍射环带半径;$ {D}_{i} $为第i个衍射环带残留区域宽度;l为透过率的损失。由公式(2)可知,残留区域宽度越大,透过率损失越大。因此,需要严格限制车削残留区域的大小。当加工衍射面形一定时,刀具半径越小时,残留区域越小,但是表面粗糙度会随刀具半径减小而变大,表面质量随之变差。同时,衍射面形的参数对刀具的选择具有一定的影响,衍射结构的深宽比影响加工表面质量,刀具的参数选择是由两个相邻环带之间的步进深度和横向距离的比值决定的。因此,有必要根据衍射面的具体参数对不同刀具参数的切削性能进行仿真计算评估。

      衍射面形的车削刀具一般有圆弧车刀、半圆弧车刀和尖刀,圆弧形车刀造成的残留区域最大,而尖刀是刀尖圆弧半径为零的刀具,因此很容易磨损,加工表面粗糙度较差,不适合较大口径的元件加工。半圆弧刀具是加工渐变锯齿衍射结构的理想工具,如图1所示,相比圆弧刀具,残留区域大小可以减少近一半。因此,对于更高精度要求的衍射光学元件加工,半圆弧车刀是更优的选择。用半圆弧车刀加工时的残留区域的尺寸可以通过下式计算获得:

      式中:$ f\left(x\right) $为衍射曲线;$ g\left(x\right) $为刀具圆弧曲线;D为残留区域的宽度;H为高度;R为刀具半径。结合公式(3)和公式(4)可以模拟计算出残留区域的精确大小,用于指导刀具半径的选择。因此,利用该计算模型可以获得合适的刀具半径。

    • 衍射光学元件是一种位相型光学元件,以光的衍射效应为基本工作原理。为了实现更丰富的光学功能,增加光学设计自由度,通常将衍射元件的微结构叠加到基底面形上。该基底面可为平面、球面或非球面。常用的衍射光学元件的数学描述如下:

      式中:$ {Z}_{base}\left(r\right) $为基底面的面型。可用高次非球面公式表示:

      式中:A、B、C、D为高阶系数;c为顶点曲率;K为二次系数。

      $ {Z}_{diff}\left(r\right) $表示衍射结构的矢高分布,可用以下公式表示:

      式中:λ为设计波长;n1为材料的折射率;n2为空气折射率;Z2、Z4、Z6为衍射面系数;$\lambda /({n}_{1}-{n}_{2})$为衍射环带深度。

      通过实验验证SPDT在衍射表面的加工能力和仿真计算模型的有效性,从而为衍射光学元件高精度批量化生产提供技术支持。设计的衍射面为平面基底,即Zbaser)=0。衍射面参数如表1所示,其归一化直径为10 mm,衍射结构的环带深度为3.07 μm,环数为14。最小环带位于最外环,约0.18 mm,衍射结构如图2所示。

      Wavelength/λDiameter/mmDepth/μmDiffractive parameters
      Z2Z4Z6Z8Z10
      632.8 nm103.07
      88.625385−0.0138
      47387
      3.480883e-0069.2470349e-007−3.6203
      993e-007

      Table 1.  Diffraction plane parameters

      Figure 2.  Diffraction surface shape

      常见的衍射元件加工方法是将每一衍射环带近似成斜平面,从而选取相应的刀具和加工工艺。近似斜平面时,残留区域最大宽度在衍射环带最外环,可以计算得到最大残留区域宽度与加工刀具的半径之间的关系:

      式中:R为刀具半径;D为残留区域宽度。

      而实际面形与斜平面会有一定差别,如图3(a)所示为近似斜平面与实际面形对应的最大残留宽度与刀具半径之间的关系。可以看到,刀具半径为0.03 mm时,两者之间的差别最大到200 nm。而且近似斜平面与实际面形在比较接近的情况下有近200 nm的误差,如图3(b)所示为衍射结构最外环的实际面形与近似斜平面的比较,当实际衍射面形陡度更大时,与斜平面之间的差异非常明显。因此,在高精度的衍射结构加工时,衍射结构的面形形状也是不可忽略的,在对刀具半径选择时需要考虑衍射面形形貌。

      根据以上仿真与分析,结合车削表面粗糙度理论公式,选用刀具半径为0.02 mm的半圆形金刚石刀具进行仿真与实验验证。首先,根据衍射面参数和刀具半径参数对残留区域大小进行仿真计算,各环带位置的残留区域大小计算结果如图4所示。

      Figure 3.  The actual plane shape of diffraction structure compared with the approximate oblique plane

      Figure 4.  Residual area simulation results

      理论上,残留区域大小随环带半径的增大而增大,从衍射面中心到边缘,加工表面的斜率逐渐增大,因此DH值随着衍射环带从中心到边缘逐渐增大。刀具半径为0.02 mm时,宽度和高度的预测值最大分别为0.38 μm和7 nm,都位于衍射元件最边缘位置。

      衍射结构的形状检测一般采用接触式轮廓仪进行测量。对原始测量曲线进行滤波和差分处理,即可得到突变点的位置信息。实际上,如图5所示,残留区域很小,在B点附近表面形状变化缓慢,实际突变点为A点。因此,一般轮廓仪分析的宽度误差是A点位置误差,即环带的位置误差,表示机床横向位置的加工误差。但阴影区域的实际宽度是A点到B点的横向距离,要得到实际宽度大小,可以根据衍射面形参数特征来求解。

      根据实验设计的衍射面形参数,衍射环带每一段曲线设为f(x),刀具圆弧曲线为g(x)。如图5所示,B点左边的曲线为f(x), B点右边的曲线为g(x)。f(x)的导数是递增的,g(x)的导数是递减的,拐点是B,所以当轮廓曲线为F(x) = f(x) + g(x)时,求曲线的二次微分拐点即可得到B点的位置,根据该方法可以计算出实际的残留区域宽度信息。

      Figure 5.  Schematic diagram of residual area width information

    • 采用Precitech Nanoform 700单点金刚石车削机床加工,用Taylor Hobson接触式轮廓仪对表面进行测量,在直径为12.7 mm的铝(Al)材料上加工。在衍射结构加工前对基面进行加工,通过补偿加工控制表面质量。降低对后续的衍射表面加工的影响,然后在基面上加工衍射结构,加工参数根据公式(1)以及实际的正交实验得到,优化的加工参数如表2所示。刀具半径的选择要考虑粗糙度和环带位置误差的影响,即需要结合公式(1)和公式(2),所选刀具半径应满足粗糙度估计值和透过率的损失在误差允许范围内。采用接触式轮廓仪测量衍射元件的轮廓,得到衍射元件截面轮廓曲线。

      Tool parametersMachining parameters
      Radius/mmRake/(°)Clearance/(°)Speed/rpmFeedrate/mm·min–1Cutting depth/μm
      0.020102 00012

      Table 2.  Tool parameters and machining parameters

      轮廓仪测得的衍射面原始轮廓如图6所示。将该轮廓曲线与设计的衍射结构相减,即可得到面形误差信息。实际检测的面形误差值PV为292 nm。结果表明,实际制造的结构形状与设计结果吻合较好。

      Figure 6.  Diffraction element profile detection results

      对原始数据进行滤波和差分处理后,得到突变点的位置信息,衍射元件的位置误差和高度误差分析结果如图7所示。可以看出,衍射元件位置和高度误差最大值分别为55 nm和16 nm。测量误差的变化趋势与预期结果基本一致,但误差幅度有所不同。位置误差和高度误差从中心到边缘都是逐渐增大,除个别波动点外,变化趋势基本相同。考虑该误差值为纳米量级,加工中的任何小的波动都会对该误差造成一定的影响,因此纳米级的误差波动是正常的。

      Figure 7.  Measurement results of diffraction structure position error

      对于台阶高度的误差,该值与加工残留区域的高度相关。残留高度越大,高度误差值越大。因此,高度误差的变化趋势与残留区域高度预测结果基本一致。考虑到加工误差,实际的误差值会比仿真计算结果大。对于衍射结构位置误差,图7 (a)为环带宽度位置误差,表示机床横向位置的加工精度。

      根据检测得到的高度误差与残留区域宽度预测模型,可以得到残留区域的宽带误差大小,结果如图8所示。可以看到,实际的残留区域宽度略大于仿真结果,最大值约为1.15 μm,变化趋势与仿真结果基本一致。由于加工误差的影响,实际结果比仿真值要大。而由于实际残留区域高度误差为纳米量级,最大值为16 nm,残留区域的宽度相比预测值的偏差影响很小。结果表明,预测模型较好地反映了残留区域大小与刀具半径和面形参数之间的关系。

      Figure 8.  Residual area width error detection results

      衍射光学元件的衍射效率主要受到加工残留区域的影响,尤其是残留区域的宽度大小。因此,根据预测模型选择合适的刀具半径时,应首先考虑宽度位置信息。同时,表面粗糙度是另一个需要考虑的因素。理论上,刀具半径越小,表面粗糙度越大。此外,当刀具半径较小时,刀具容易磨损,损伤表面。如图9所示,测量衍射元件中心区域的表面粗糙度。当刀具半径为0.02 mm时,粗糙度Sq的值为5.6 nm。

      Figure 9.  Measurement results of surface roughness in the center region of diffraction element

      最终加工的衍射元件面形误差为292 nm,衍射环带位置误差最大为55 nm,高度误差最大为16 nm,粗糙度为5.6 nm。

    • 基于单点金刚石车削加工衍射结构的误差分析,采用半圆弧刀具加工的衍射元件具有较高的加工精度和位置精度。在对衍射元件加工前,利用建立的半圆刀具加工衍射结构环带位置误差仿真计算模型,结合表面粗糙度影响因素选择合适的刀具半径。在对基底面形控制下,可以得到高精度的衍射光学元件。根据设计衍射结构面形与仿真模型,选择刀具半径为0.02 mm的半圆形金刚石刀具车削,最终加工的衍射元件面形误差为292 nm,衍射环带位置误差小于55 nm,高度误差小于16 nm,粗糙度为5.6 nm。

      实验结果表明,该预测模型可以指导衍射光学元件高精度表面形貌的获取,有利于提高衍射光学元件的成像质量。该研究结果对高精度衍射光学元件的研制提供了技术支持,具有广泛的工程应用价值。

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