A new designed ultra-high precision profiler

Higashi, Y.; Takaie, Yuichi; Endo, Kazuhiko; Kume, Tatsuya; Enami, Kazuhiro; Yamauchi, Kazuto; Yamamura, Kazuya; Sano, Hideto; Ueno, K.; Mori, Yojiro

doi:10.1117/12.617986

Cited by 6 publications

(6 citation statements)

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“…Figure 1 illustrates the measurement principle of the profiler. This measuring method is based on the straightness of laser light and the accuracy of a rotational goniometer [ 7 , 8 ]. Detector quadrant photodiode (QPD) is established at the rotation center of two sets of goniometers at the optical system side; moreover, a light source is set at the position where it is equal to a rotation center optically, and a measured surface is assembled so that the distance becomes R y from the original point of the measured surface to the rotation center of two sets of goniometers at the sample system side.…”

Section: Reviewmentioning

confidence: 99%

Profile measurement of concave spherical mirror and a flat mirror using a high-speed nanoprofiler

et al. 2013

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Ultraprecise aspheric mirrors that offer nanofocusing and high coherence are indispensable for developing third-generation synchrotron radiation and X-ray free-electron laser sources. In industry, the extreme ultraviolet (wavelength: 13.5 nm) lithography used for high-accuracy aspheric mirrors is a promising technology for fabricating semiconductor devices. In addition, ultraprecise mirrors with a radius of curvature of less than 10 mm are needed in many digital video instruments. We developed a new type of nanoprofiler that traces the normal vector of a mirror's surface. The principle of our measuring method is that the normal vector at each point on the surface is determined by making the incident light beam on the mirror surface and the reflected beam at that point coincide, using two sets of two pairs of goniometers and one linear stage. From the acquired normal vectors and their coordinates, the three-dimensional shape is calculated by a reconstruction algorithm. The characteristics of the measuring method are as follows: the profiler uses the straightness of laser light without using a reference surface. Surfaces of any shape can be measured, and there is no limit on the aperture size. We calibrated this nanoprofiler by considering the system error resulting from the assembly error and encoder scale error, and evaluated the performance at the nanometer scale. We suppressed the effect of random errors by maintaining the temperature in a constant-temperature room within ±0.01°C. We measured a concave spherical mirror with a radius of curvature of 400 mm and a flat mirror and compared the results with those obtained using a Fizeau interferometer. The profiles of the mirrors were consistent within the range of system errors.

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Section: Reviewmentioning

confidence: 99%

Profile measurement of concave spherical mirror and a flat mirror using a high-speed nanoprofiler

et al. 2013

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“…Figure 1 illustrates the principle underlying the proposed profiler, which is based on the straightness of laser light and the high accuracy of rotational goniometers. 8,9 Our measurement method involves two components: an optical head and a sample motion unit. The optical head motion unit consists of two goniometers (rotating around the θ -and ϕ-axes), one linear motion stage (moving along the y-axis), and a sample motion unit consisting of two goniometers (rotating around the α-and β-axes).…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional surface figure measurement of high-accuracy spherical mirror with nanoprofiler using normal vector tracing method

Kudo

Okuda

Usuki

et al. 2014

Review of Scientific Instruments

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Processing technology using an extreme ultraviolet light source, e.g., next-generation lithography, requires next-generation high-accuracy mirrors. As it will be difficult to attain the degree of precision required by next-generation high-accuracy mirrors such as aspherical mirrors through conventional processing methods, rapid progress in nanomeasurement technologies will be needed to produce such mirrors. Because the measuring methods used for the surface figure measurement of next-generation mirrors will require high precision, we have developed a novel nanoprofiler that can measure the figures of high-accuracy mirrors without the use of a reference surface. Because the accuracy of the proposed method is not limited by the accuracy of a reference surface, the measurement of free-form mirrors is expected to be realized. By using an algorithm to process normal vectors and their coordinate values at the measurement point obtained by a nanoprofiler, our measurement method can reconstruct three-dimensional shapes. First, we measured the surface of a concave spherical mirror with a 1000-mm radius of curvature using the proposed method, and the measurement repeatability is evaluated as 0.6 nm. Sub-nanometer repeatability is realized, and an increase in the repeatability would be expected by improving the dynamic stiffness of the nanoprofiler. The uncertainty of the measurement using the present apparatus is estimated to be approximately 10 nm by numerical simulation. Further, the uncertainty of a Fizeau interferometer is also approximately 10 nm. The results obtained using the proposed method are compared with those obtained using a Fizeau interferometer. The resulting profiles are consistent within the range of each uncertainty over the middle portions of the mirror.

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“…These goniostages make it possible to attain an angular resolution of 0.018 mrad by electrically dividing one pulse of the rotary encoder. The anglepositioning accuracy of the goniometers was calibrated [2]. We constructed a small shelter to ensure insulation from external temperature fluctuations using 100-mm-thick styrol foam in a temperature-controlled room, which itself was designed to limit temperature changes to within 70.3 1C/day.…”

Section: Principle Of Measuring Methodsmentioning

confidence: 99%

“…In the presently designed ultrahigh precision profiler, the principle of our measurement method is that the normal vectors at each point on the surface are determined by making the incident light beam on the mirror surface and the reflected beam at that point coincident [1,2]. The gradients at each point are calculated from the normal vector, and the surface profile is then obtained by integrating the gradients.…”

Section: Introductionmentioning

confidence: 99%

Surface gradient integrated profiler for X-ray and EUV optics

Higashi

Takaie

Endo

et al. 2007

Science and Technology of Advanced Materials

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A new ultraprecise profiler has been developed to measure, for example, asymmetric and aspheric profiles. The principle of our measuring method is that the normal vector at each point on the surface is determined by making the incident light beam on the mirror surface and the reflected beam at that point of coincident. The gradient at each point is calculated from the normal vector, and the surface profile is then obtained by integrating the gradients. The measuring instrument was designed in accordance with the above principle. In the design, four ultraprecise goniometers were applied to adjust the light axis for normal vector measurement. The anglepositioning resolution and accuracy of each goniometer are, respectively, 0.018 and 0.2 mrad. Thus, in the measuring instrument, the most important factor is the accuracy of the normal vectors measured by the goniometers. Therefore, the rotating angle-positioning errors were measured and calibrated. An elliptical profile mirror for nanometer hard-X-ray focusing was measured, and compared with the measured profile using a stitching interferometer. The absolute measurement accuracy of approximately 5 nm (peak-to-valley) was achieved. Then the measurements of 1000-mm-long flat, spherical and parabolic mirrors were demonstrated. The surface profiles of the mirrors were obtained by integrating the interpolated gradient. r

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A new designed ultra-high precision profiler

Cited by 6 publications

References 0 publications

Profile measurement of concave spherical mirror and a flat mirror using a high-speed nanoprofiler

Profile measurement of concave spherical mirror and a flat mirror using a high-speed nanoprofiler

Three-dimensional surface figure measurement of high-accuracy spherical mirror with nanoprofiler using normal vector tracing method

Surface gradient integrated profiler for X-ray and EUV optics

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