衍射光学元件热稳定性的分析

本文对折射元件和衍射元件的温度特性进行了分析,建立了透镜焦距和衍射效率随环境温度的变化关系,通过施密特红外望远镜系统的设计,比较了折射非球面与衍射光学校正板的温度特性对系统光学传递函数的影响,结果表明衍射光学元件具有较好的热稳定性.     

体全息光栅透镜的设计和应用

设计了一种新型的体全息光栅透镜, 在一块光学平板（体全息记录材料）内可以将输入光束产生横向传输并聚焦, 或对输入光点产生横传的准直. 它由一束平面波和一束球面波正交入射到光学平板上干涉形成的. 研究了该体全息透镜的光栅间距变化情况, 为设计和制备体全息光栅透镜及相关器件提供了理论依据. 基于两光束耦合波理论, 得到了该光栅透镜的耦合波方程, 近似计算了该透镜的衍射效率及其达到高衍射效率时透镜的最佳尺寸. 最后, 讨论了该透镜在集成光学等领域中的应用.     

含有双层衍射光学元件的中波/长波消热差光学系统的设计

建立了工作在一定入射角度范围内的多层衍射光学元件的复合带宽积分平均衍射效率的分析模型。基于衍射光学元件所具有的独特的消色差和消热差性质,设计了一个含有双层衍射光学元件的工作在(3.7~4.8) μm和(7.7~9.5) μm红外双波段光学系统。光学系统的焦距为200 mm,F#为2。采用像元数为320×256、间距为30 μm的制冷型探测器。该系统在空间频率17 lp/mm时,中、长波红外MTF分别高于0.66和0.54;最大RMS半径小于11.702 μm;波前像差小于0.191 7λ;最大离焦量小于焦深;在-55℃~71℃范围内实现了无热化设计。入射到衍射面上的角度为0°~5.19°,该双层衍射光学元件在中波和长波波段的复合带宽积分平均衍射效率分别为99.81%和97.36%。含有双层衍射光学元件的红外双波段光学系统结构简单,像质优良,可以广泛应用于军事探测系统中。     

VECTOR COUPLED-WAVE THEORY OF DIFFRACTIVE OPTICS IN THE RESONANCE DOMAIN

In this paper, based on Maxwell's equations and boundary continuity condi-tions of electromagnetic fields, we derive rigorous vector coupled-wave equations of two-dimensional diffractive patterns for an arbitrary polarization in the resonance domain, and describe the solution to these equations. We verify this theory with a practical example, and show the effectiveness of this method for the resonance-domain diffractive optics.     

Some focusing properties of chirped gratings

In the past the focusing properties of chirped grating structures have been investigated in various disciplines including optics, acousto-optics and acoustics. In this paper we present the results of a detailed theoretical and experimental study of one such amplitude grating structure, namely the chirped optical diffraction grating, although many of the conclusions are of more general validity. We derive some useful fundamental properties of such focusing gratings, and show that to first order their behaviour is similar to that of various other classical components such as focusing lenses, grating spectrometers and matched filters for chirped waveforms. However, we also describe a range of second-order differences in behaviour, for example concerning the physical location of the multiple foci, and the sidelobe structures within and perpendicular to the focal plane. For devices of large numerical aperture we demonstrate the advantages of using a non-linear grating structure — for example, for sidelobe suppression in the focal plane - and point out that surface acoustic wave (SAW) techniques can be used to generate the non-linear chirp waveforms necessary to implement such gratings in acousto-optic devices.     

利用严格模式理论分析光栅透镜的衍射特性

光栅透镜因其独特的光学性能而具有广泛的应用.根据光栅透镜的线宽和间距微小渐变的特点,建立了光栅透镜的物理模型,并利用严格模式理论对其衍射特性进行分析.该方法物理概念清晰、公式简洁.对光栅透镜实现谐波分离、聚焦功能时的衍射效率与槽深关系的计算结果表明,其计算速度快、数值计算结果准确可靠.并对加工误差的影响进行了模拟计算,说明了在当前的微细加工的工艺水平条件下,能够制作出满足ICF系统要求的光栅透镜.实验上制作了尺寸为100 mm的大面积光栅透镜,其衍射效率的实验测试结果与理论计算结果一致.     

含双层衍射元件消热差长波红外光学系统设计

采用多层衍射元件是实现宽波段高衍射效率的有效方法,设计了一个含双层衍射元件-30℃～70℃消热差系统。通过合理选择衍射面的基底材料,优化衍射表面的浮雕深度,设计出红外宽波段高衍射效率的消热差光学系统。设计结果表明,在整个设计温度范围内,该光学系统成像质量良好,光学传递函数在16lp/mm时均在0.6以上。     

宽光谱超大孔径反衍望远系统设计

二元光学元件具有许多传统光学元件无法比拟的优越性。利用2个二元光学元件作为系统的物镜和目镜,通过确定各元件的基本结构、孔径大小,设计了25m的超大孔径反衍混合望远系统。所设计系统的弥散斑大小及MTF函数都能够达到设计要求。使用谐衍射透镜代替普通衍射透镜,对系统进一步改进,使望远系统获得了较宽的光谱范围。试验结果表明:改进后的系统无论在单一光谱、多频带光谱或者连续光谱范围,都能够获得接近衍射极限的成像质量。     

Annular-focus zone lens for increasing the intensities of created Bessel beams

In this paper we proposes a new concept of annular-focus zone lens and its design procedure based on binary optics. An investigation of the diffraction efficiencies and the transverse intensity distributions on the focal plane of the designed annular-focus zone lenses is presented. This special kind of zone lens may be used to increase the intensities of Durnin's diffraction-free beams.     

Efficiency of Blazed Diffractive Optics Produced by Diamond Turning

In blazed diffractive optics produced by the diamond turning process, the finite size of the tool causes a decrease in diffraction efficiency. To analyze the influence of the tool, we evaluate first-order diffraction efficiency of periodic gratings based on the electromagnetic theory. The design indices of the diffractive optics for higher efficiency are shown. Even with the same power of diffractive optics, the efficiency differs with the front or back side of the surface. The efficiency of a diffractive-refractive hybrid lens depends on the curvature of the refractive surface.     

Efficient high-order diffraction of extreme-ultraviolet light and soft x-rays by nanostructured volume gratings

We report what is believed to be the first demonstration that volume gratings diffract extreme-ultraviolet light (EUV) or soft x-rays into high orders approximately an order of magnitude more efficiently than predicted by classical thin-grating theory. At the 13-nm wavelength, copolymer grating structures with 200-nm period and aspect ratios of ~10:1 achieved diffraction efficiencies of 11.2%, 15.3%, 11.5%, and 9.1% in the orders m of 2, 3, 4, and 5, respectively. In addition, the measured transmission spectra are consistent with electrodynamic calculations by coupled-wave theory. High-order diffraction can now be employed for substantially improved diffractive EUV and x-ray optics, e.g., highly resolving diffractive lenses and large-aperture condensers.     

双曲柱面透射光栅衍射的数值分析

建立了双曲柱面透射光栅的数学模型。由光程的定义导出平行光通过单个双曲柱面的复振幅透过率。用傅里叶光学方法得出双曲柱面透射光栅在频谱面上的光强分布表达式。使用MATLAB软件模拟出其衍射光强随双曲线半实轴变化的分布规律,得出的衍射花样与理论分析一致。最后从理论上指出双曲柱面透射光栅在光学领域的应用。     

折/衍混合LWIR凝视成像系统的杂散光分析

本文对一折/衍混合长波红外(LWIR)凝视成像系统进行了杂散光分析,在此LWIR系统中,含有一个用金刚石车削技术制作的衍射光学元件(DOE)。本文中,对DOE的不同衍射级次、光学表面的多次反射、镜筒内壁的反射等主要杂散光源利用LightTools软件进行了分析,对6种二次反射的模拟结果表明,对归一化的光源,理想光路的像面辐照度为100 W/mm2,每种二次反射会给像面带来0.01W/mm2的辐照度;对于反射率为10％的镜筒内壁,带来的像面辐照为0.01W/mm2。并利用该LWIR凝视成像光学系统进行了相关实验,实验结果证明了上述分析的正确性,有利于对LWIR凝视成像系统光学性能的进一步理解和杂散光的抑制。     

Optimized staircase profiles for diffractive optical devices made from absorbing materials

We report on the optimization of staircase grating profiles for the case of absorbing grating materials. Using a simple numerical algorithm, we determined the grating parameters, maximizing the first-order diffraction efficiency for different numbers of staircase steps. The results show that there is a significant difference between the staircase profiles for nonnegligible and negligible absorption. The obtained solutions are of importance for diffractive optics in the soft-x-ray and extreme-ultraviolet ranges.     

Blazed binary subwavelength gratings with efficiencies larger than those of conventional échelette gratings

We introduce a new structural cutoff beyond which subwavelength gratings cease to behave as homogeneous media and discuss its effects on the proper selection of the sampling periods of subwavelength diffractive elements. According to this analysis, a 3lambda-period blazed binary grating composed of square pillars is designed for He-Ne operation and is fabricated by etching of a TiO>(2) layer deposited upon a glass substrate. Its first-order measured diffraction efficiency is 12% larger than the theoretical efficiency of an ideal blazed échelette grating in glass with the same period.     

双波长共焦衍射光学元件分析与设计

报道二维纯位相环带衍射光学透镜的研究。结果表明，在确定位置的像平面的光强分布呈现相当理想的光聚焦作用；同时以１．０６μｍ和０．６３２８μｍ两种波长为例，对双波长二维成像的环带衍射透镜进行分析计算，结果表明二种波长的光束都能聚焦于同一像平面。这种元件可方便地用于非可见激光中的对焦与光路调整。     

Bypassing and cutting through 1D photonic crystals by ultra-shallow wet-etched resonant gratings

The electromagnetic field in subwavelength resonant diffractive optical elements is so concentrated that a very shallow surface corrugation obtained by wet chemical micro–nano-etching is sufficient to give rise to high contrast diffraction effects allowing a high wavelength-, polarization- or transverse-mode-selectivity which is not achievable by conventional diffractive elements. Two examples of polarizing laser mirrors at both extremes of the optical spectrum with wet-etched grating bypassing and cutting through the 1D photonic crystal are demonstrated.     

CGQ-II车间数字干涉仪的几种特殊检测的应用

最近研制与改进的几台CQG II型车间数字干涉仪除应用于平面及球面的面形测量、获得面形误差PV、RMS或N、ΔN外 ,还可以广泛地应用于下列几种特殊的应用 :( 1)微型光学件的检测 :借助 φ60mm～φ15mm放大系统可以测量 φ1mm平面 ;( 2 )光学平行平面的透过波面畸变检测 ;( 3)棱镜角度及面形检测 ;( 4)非球面检测 :低陡度非球面、二次曲面及非球面准直系统 ;( 5 )衍射光检测 ;( 6)镜头的调制传递函数 (MTF)的检测 ;( 7)金属表面 (模具 )或镀反射膜光学件的检测。仪器的口径为 60mm ,平面精度为λ/2 0 ,球面精度为λ/10 ,λ =632 8nm ,对以上的应用均列举了生产实际应用或科研应用的实例。     

Towards dualband megapixel QWIP focal plane arrays

Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024 × 1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NEΔT) of 17 mK at a 95 K operating temperature with f/2.5 optics at 300 K background and the LWIR detector array has demonstrated a NEΔT of 13 mK at a 70 K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90 K and 70 K operating temperatures respectively, with similar optical and background conditions. In addition, we have demonstrated MWIR and LWIR pixel co-registered simultaneously readable dualband QWIP focal plane arrays. In this paper, we will discuss the performance in terms of quantum efficiency, NEΔT, uniformity, operability, and modulation transfer functions of the 1024 × 1024 pixel arrays and the progress of dualband QWIP focal plane array development work.     

紧凑型8～12 μm波段折/衍混合双位置两档变焦光学系统设计

设计了工作于8～12 μm波段的折/衍混合双位置两档变焦光学系统.该系统变焦过程中相对孔径保持不变,F/#为1.7,系统变倍比为3.75∶1.大视场角为19.2°,有效焦距33 mm,用于在大范围内搜索目标;小视场角为5.1°,有效焦距125 mm,用于对目标进行具体分析.系统采用锗和硒化锌两种材料,为四片镜结构,仅通过两片透镜的轴向移动便可完成两个视场的切换.系统中引入二元面和高次非球面,使系统结构简化,并极大地提高了成像质量.该系统适用于像元尺寸20 μm的非致冷式面阵探测器,可广泛应用于军事扫描成像和红外前视系统中.