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Near-field holography (NFH), with its virtues of precise critical dimensions and high throughput, has a great potential for the realization of soft x-ray diffraction gratings. We show that NFH with reflections reduced by the integration of antireflective coatings (ARCs) simplifies the NFH process relative to that of setups using refractive index liquids. Based on the proposed NFH with ARCs, gold-coated laminar gratings were fabricated using NFH and subsequent ion beam etching. The efficiency angular spectrum shows that the stray light of the gratings is reduced one level of magnitude by the suppression of interface reflections during NFH.

We present a replication process, named reversal soft ultraviolet (UV) nanoimprint, to fabricate a high-aspect-ratio flexible subwavelength grating (SWG) on a polyurethane acrylate (PUA). This nanopatterning technique consists of casting, reversal UV imprint, and dry release. The UV curing process of PUA to avoid pattern collapse is investigated. Revalpha film acts as the supporting and sacrificial layer during the whole process due to its special surface energy property. The free-standing PUA structures with a period of 200 nm and a depth of 350 nm can be automatically released from the Revalpha film by heating. The PUA resist is well suited to replicate fine patterns of the mold with high aspect ratio and large area precisely and uniformly for low surface energy and low viscosity. The measured transmittance is compared with the calculation results based on rigorous coupled-wave analysis in the wavelength region ranging from 500 to 800 nm. The experimental results agree well with the theoretical calculations.

To eliminate the eccentricity effect, a new method for measuring the groove density of a variable-line-space grating was adapted. Based on grating equation, groove density is calculated by measuring the internal angles between zeroth-order and first-order diffracted light for two different wavelengths with the same angle of incidence. The measurement system mainly includes two laser sources, a phase plate, plane mirror, and charge coupled device. The measurement results of a variable-line-space grating demonstrate that the experiment data agree well with theoretical values, and the value of measurement error (ΔN/N) is less than 2.72 × 10(-4).

The basic principle and method to generate structural color from the photoresist grating of the multilayer dielectric diffraction grating are introduced. Rigorous coupled-wave analysis is used for computation with the open software RCWA-1D. The relationships between the characteristics of the photoresist and the structural color are explained. This paper discusses the effect of light source characteristics on the duty cycle color resolution, indicating that TE polarization is better than TM polarization, and the FWHM should be sufficiently large with an optimized value for the incident angle.

The structure principle and performance of the measure system of three-dimensional resolution of time, space and spectrum for laser-produced plasma are presented. The typical experimental results are also given.

This paper describes an effective method for the measurements of large aperture sampling grating , the sampling efficiency the sampling focal length and the sampling angle. By using a 351nm collimation laser source to scan the full aperture of the sampling grating in every subregion, the diffraction power of q0q order and q+1q order can be obtained synchronously by two standard integrating balls, And then by calculating the sampling efficiency of this subregion and splicing the acquisition data, we can get the averaged grating sampling efficiency in the full aperture .Based on this method, we can effectively eliminate the effect of the output instability of laser source, decrease the uncertainty of test results. According to the fabrication principle of the sampling grating , measurements for the sampling focal length and the sampling angle can be performed. Test rersults indicate that this method can be used to measure large aperture sampling gratings .

As a new type of grating, the freestanding blazed transmission grating combines the advantages of traditional transmission gratings (low mass, relaxed alignment and flatness figure insensitivity) with those of reflection gratings (high broadband diffraction efficiency, high spectral resolution). A freestanding blazed transmission grating with period of 1μm was successfully fabricated by holographic lithography and anisotropic wet etching of silicon. The duty cycle is about 0.13. The aspect ratio of a single grating bar is about 77. The thickness is 10μm and the open area fraction is about 58.8%. The size of a single die is 15mm×15mm divided into four 5mm ×5mm windows. The diffraction efficiency of the grating was measured at the National Synchrotron Radiation Laboratory in the wavelength region of 5-50nm. The results show a strong blazing effect in the direction of specular reflection from mirror-like grating sidewalls, as expected.

A broadband [SiC/W/Ir](2) multilayer coating was deposited onto a diffraction grating to enhance the grating efficiency in the 50-100 nm wavelength range in a Seya-Namioka mount. The holographic ion-beam etched grating had a laminar profile with 1200 lines/mm. The coating was designed by using the subquarterwave multilayer theory. The measurement results show that the efficiency in the -1st diffraction order is greater than 9.3% throughout the wavelength range of 50-100 nm, which is obviously higher than that of single-layer gratings with SiC, Ir, or Au coatings.

We demonstrate a method of fabricating varied-line-spacing grating by employing elastic medium with variable vertical section. The advantages of this technique include continuous variation of line spacing, high fabrication efficiency, low cost, etc. It is very difficult or impractical to produce this variation of line spacing by traditional interference lithography. This kind of grating can be used in an optical position sensor to improve the precision of the sensor.

We present new progress of the diffraction grating interferometer being pre-aligned used a double frequency grating. To measure the parallelism of the double frequency grating to a nicety before being built in the interferometer, a device based on Diffraction Technique for measuring the parallelism of the double frequency grating is designed. It is built of a semiconductor laser, a collimator, gratings, a precision turnplate, a beeline workbench, a redressal shelves, a ccd detector. The system error of the device is analyzed in this paper, and the parallelism of the double frequency grating is measured by this device. The results demonstrate that the diffraction measuring device suits the parallelism measured the diffracting grating interferometer based on the double frequency grating of that parallelism can attain a high pre-aligning precision.

A binary transmission phase grating is designed to operate as a dispersive element used in soft x-ray plasma diagnostic in ICF (inertial confinement fusion). The first and zero orders diffraction efficiency is simulated as a function of wave length and grating thickness. It is shown that the first order diffraction efficiency of a transmission phase grating can be up to 23.3% of the incident light, whereas that is not more than 10% for a conventional amplitude transmission grating. The transmission phase grating is fabricated in gold film supported by polyimide membranes using holography and ion beam etching method. The primary experimental results are presented.

Parameters of two spherical waves are firstly optimized to get the exact groove densities of diffractive gratings. Consequently, the groove density differences between on the plane and on the curved substrates are derived. Therefore, some experimental results are provided to demonstrate the validity of this method above. Meanwhile, the curvatures of the substrates are measured three times by using long trace profiler (LTP), which assures the repeatability of the bending technique for grating substrates. At last, the advantage of this method is exhibited through comparing the errors of grating groove density fabricated by this technique with only two spherical waves.

The major etching processes of a large-aperture multilayer diffraction grating, including the uniformity of the ion beam current along the major axis and the on-line measurement of the diffraction intensity distribution are described. A large-aperture ion beam etcher with radio frequency linear source has been developed to fabricate large-aperture diffractive optical elements. The length with ±5.1% uniformity of the ion beam current distribution along the major axis is 30 cm. A series of multilayer diffraction gratings were etched successfully by using this etcher with CHF 3 chemistry. Multilayer diffraction gratings on a 80 mm×150 mm BK7 substrate etched for laser systems are shown. The grating exhibits an averaged diffraction efficiency about 96% at TE polarization of 1 064 nm light viewed at Littrow angle.

The short wavelength, high brightness and good spatial coherence of soft x-ray lasers make them ideal sources for the diagnostics of dense plasmas. As a widely used diagnosing tool in the research of laser-produced plasma, interferometry has many advantages in the accurate measurement of the plasma electron density because it directly gives refraction index mapping from the interference pattern processing. The electron density gradient and electron density of larger variety plasma will be probed by the soft X-ray diffraction grating Mach-Zehnder interferometer (DGI). At the wavelength 13.9nm which our DGI uses, we fabricate a laminar grating used as the splitter grating. Its groove density is 1000g/mm, groove depth is 13nm, duty cycle is 0.4±10%. The zero and first diffracted order beams have an equal metrical diffraction efficiency about 25 percent at 81.3 degrees, and the maximum of the product is 7.6 percent at 81.2 degrees. The results illustrate the laminar grating is suitable for being used as a new pattern splitter grating at the wavelength 13.9nm.

It is known that rectangular grooves profile and various duty cycles (line to pitch) are required to attain maximum efficiency. The gold transmission phase gratings have been fabricated using holography and ion-beam etching techniques. The latent image monitoring technique and real time end-point detection technique were utilized to improve control of the shape of grooves and duty cycle during exposure and development, respectively. It is difficult to produce gratings with larger duty cycle in photoresist on gold for standing wave, nevertheless it is revealed in our work that the duty cycle can be more than 0.4 for the case for photoresist on gold substrates if development is stopped where the slope of the monitoring curve begins to drop off, not at the peak of the diffracted signal. In ion-beam milling, the influence of redeposition on the shape of grooves and duty cycle has been overcome by using a thin mask of Chromium with a comparatively low ion-etch rate and tilting and rotating substrates beneath the ion beam. Finally, some gold phase gratings with the duty cycles in the range of 0.25-0.45 have been obtained, whose duty cycle value is about 0.45, and their grooves profile is trapezoidal profile whose left and right facets are both more than 83 degrees approximately.

Fabrication and testing results of sine-top, high-efficiency, broadband gold-coated gratings (BGCG) for high-power laser pulse compression applications are reported. These gratings differ from conventional metal-on-photoresist pulse compression gratings in that the gratings patterns are generated by directly etching the quartz substrate. The groove depth and duty cycle of the photoresist mask was controlled by changing photoresist thickness and adjusting exposure and development times, respectively. The duty cycle of the photoresist mask was further corrected by oxygen plasma etching. Using this method, high efficiency, sine-top, BGCG with line densities of 1740 lines/mm was achieved. The average diffraction efficiency at the-1st order was 89.2% and the peak value was 90% for TM polarized light as the wavelength increases from 750 to 850 nm.

Diffraction gratings are designed for grazing-incidence operation in the soft x-ray spectral region. The efficiencies for various diffraction orders are simulated as a function of angle of incidence and blazed angles. According to the beat phenomenon, the grating pattern with double-frequency on the same substrate is recorded in a holographic way. The blazed grating will be fabricated using holography and ion beam etching method. The primary experimental results are presented. This kind of blazed grating is a key element used as a beam splitter of soft x-ray Mach-Zehnder interferometer, which is a new tool to diagnose the plasma generated by the laser-based inertial confinement fusion.

Holographic and ion beam etching technique has become routine means for fabricating vacuum ultraviolet and soft x-ray diffraction gratings. A novel technique has been successfully, in which oxygen reactive ions etching was used to achieve resist ashing of the grating, to fabricate diffraction gratings with holographic ion beam etching. The new technique was used to fabricate a spherical blazed grating, 1200g/mm and 130 nm blazed wavelength, and some laminar gratings for monochromators in the beamline of National Synchrotron Radiation Laboratory. The results show that the new technique can considerably lower the stringent requirements of holographic exposure and development, and makes it controllable to make smooth grooves with desirable depth and duty cycle. A gold transmission grating is one of the critical elements in the soft x-ray spectrometer for plasma diagnostics. With holographic-ion beam etching technique, a number of self-supporting transmission gratings have been fabricated for inertial confinement fusion (ICF) diagnosis.

In order to improve the efficiency uniformity of large-aperture beam sampling gratings (BSGs), a conventional chemical mechanical polishing (CMP) process of fused silica by CeO₂ slurry is proposed to modify their groove profiles. With the proposed CMP process, the efficiency uniformity of several BSGs with an aperture of 430 mm×430 mm has been successfully controlled within an rms of 5%. The proposed CMP process is an effective method to improve the efficiency uniformity of large-aperture BSGs. Using the proposed CMP process, the requirement of the uniformity of the holographic ion beam etching process can be released in the realization of large-aperture BSGs.

With holographic-ion beam etching technique, a number of self-supporting transmission gratings have been fabricated for inertial confinement fusion diagnosis. In addition to the general process, a practical method for monitoring the evolution of the grating structures exposed in photoresist during development of the resist. The real-time monitor technique developed here is relatively simple in comparison with a He-Ne laser and detector, which needs delicate control.

We present the recent advances achieved in the Changchun Institute of Optics and Fine Mechanics, Chinese Academy of Science, in the field of the soft X-ray etched multilayer optics. In the present study, Mo and Si have been chosen as materials for the scattering layer and space layer soft X-ray multilayer, respectively. The fabrication of Mo/Si multilayer used by the magnetron sputtering, the patterned resist was obtained by optical holography, and the pattern of the resist was transferred into the multilayer by the ion beam etching. The several components based on soft X-ray etched multilayer were measured by grazing incidence X-ray reflectance measurements at (lambda) equals 0.154 nm (Cu-K (alpha )) using a conventional diffractometer.

In this paper a brief description is given to introduce the activities of the manufacturing technology using the synchrotron radiation light source in the National Synchrotron Radiation Laboratory (NSRL). The light source in NSRL is a dedicated synchrotron radiation facility in China. Five beamlines and corresponding experimental stations, including soft x-ray lithography, have been constructed. The main experimental results obtained from the soft x-ray lithography station are reported. We have fabricated some devices using the synchrotron radiation lithography, for example, the high electron mobility transistor, high T c superconductor infrared detector-array, diffraction grating, and micro condenser zone plate. A simple method for the achievement of synchrotron radiation x-ray lithography mask will also be presented. The LIGA (German abbreviation for: Lithograpie, Galvanoforming, and Abforming) technique has been developed in NSRL. It is the most promising technique for the fabrication of three-dimensional microstructures. We are successful in making several microdevices by deep x-ray lithography and microelectroforming, such as microgearwheel, micro acceleration sensor.

A new electronic shearing speckle pattern interferometry using a special Ronchi grating as the shearing element has been developed and applied to deformation measurement and non destructive testing (NDT) in the practical environment. This special designed Ronchi grating is a kind of phase grating. It can make zero order and all even order beams disappear and among all odd order beams the +/- 1 order beams are much stronger than others. This new shearing element has many advantages, such as small volume, light weight, lower price, lower energy lost and good quality of shearing image. The experimental results show that it is good at electronic shearography.

Laminar-type gratings as soft x-ray beam splitters for interferometry are presented. Gold-coated grating beam splitters with 1000 lines/mm are designed for grazing incidence operation at 13.9 nm. They are routinely fabricated using electron beam lithography and ion etching techniques. The laminar grating is measured to have almost equal absolute efficiencies of about 20% in the zeroth and -1st orders, which enables a fringe visibility up to 0.99 in the interferometer. The discrepancy of the grating profiles between the optimized theoretical and the experimental results is analyzed according to the comparison of the optimized simulation results and the measurement realization of the grating efficiencies. By a precise control of the grating profile, the grating efficiency in the -1st order and the fringe visibility could be improved to 25% and 1, respectively.

We propose a general correction method for the efficiency measurement of optical components in the 45-110 nm range to eliminate the contamination of higher-order harmonics at beamline U27 of the Hefei Light Source (HLS). The influence of harmonics can be deducted effectively from the initial measurement results through the analysis of the proportion of harmonics with a transmission grating and the efficiency measurement of optical elements at the harmonics wavelengths. The reflectivity measurement of a gold film is performed at the beamline to verify its validity. Results indicate that the corrected reflectivity is in good agreement with the theoretical value. The maximal deviation amounts to 1.93% at a wavelength of 85 nm and an incident angle of 5?.

Grating beam splitters have been fabricated for soft X-ray Mach- Zehnder interferometer using holographic interference lithography. The grating beam splitter consists of two gratings, one works at X-ray laser wavelength of 13.9 nm with the spatial frequency of 1000 lines/mm as the operation grating, the other works at visible wavelength of 632.8 nm for pre-aligning the X-ray interferometer with the spatial frequency of 22 lines/mm as the pre-alignment grating. The two gratings lie vertically on the same substrate. The main feature of the beam splitter is the use of low-spatial- frequency beat grating of a holographic double frequency grating as the pre-alignment grating of the X-ray interferometer. The grating line parallelism between the two gratings can be judged by observing the diffraction patterns of the pre-alignment grating directly.

Varied-line-spacing gratings are used in soft-x-ray monochromators and spectrometers because of their ability to correct various aberrations by varying the groove density. A curved grating blank in a Rowland circle mounting could eliminate primary aberrations. Bending a plane constant-groove-density grating into a desirable surface can eliminate higher-order aberrations as a result of the change in surface profile and groove density. This provides a simple means for improving the imaging properties. When used in a monochromator, the grating can be bent to different degrees to minimize aberrations at all wavelengths. General formulas concerning the transformations of groove function, groove density, and groove spacing are presented for the bending grating. Analytic results with a numerical example show the significant properties of the system.

A long trace profiler method has been developed to measure the groove density of concave gratings in National Synchrotron Radiation Laboratory recently. With the aid of large angular acceptance (35mrad), it is suitable for precise measurement of concave or convex gratings with high curvatures. The effects of the slope variations along its substrate are discussed in detail. To eliminate the off-axis errors, which are the essential error sources in the measuring system based on rotating mounts of gratings, an error-reduced method is introduced consequently. A commercially available concave grating with a curvature radius of 998mm is measured and the relative groove density error δN∕N is about 4×10−5 rms.

Multilayer phase gratings have higher diffraction efficiency than amplitude gratings in the soft x-ray region. The authors give a detailed description of the fabrication, characterization, and performance of soft x-ray phase modulation multilayer laminar gratings. The experimental results are discussed and compared with theory.