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Large-aperture lens used for single-lens reflex cameras is generally produced by both ultra-precision grinding and polishing because a mass-produced lens by molding process can hardly achieve the required form accuracy and surface quality. Recently, grinding process of an optical glass should make surface quality as high as possible in order to reduce removal amount in polishing process. Accordingly, evaluation of subsurface damage induced under various grinding conditions has been required because subsurface damage leads to crack initiation or deterioration of the performance. However, evaluation method of subsurface damage on the spherical glass lens after grinding has not yet been established.In this study, the quantitative evaluation method by applying wet-etching of hydrofluoric acid (HF) is proposed, then its validity is verified. From the experimental results, we clarify to evaluate the subsurface damage by examining the surface transition according to etching time.

The demand for large aperture lenses with high surface quality and form accuracy used for single-lens reflex cameras has been increasing. Generally, large aperture glass lenses are produced by ultra-precision grinding. Considering the increasing global competition, the grinding process has to be improved. However, highly efficient grinding causes worse surface quality, which leads to much polishing and ultimately results in lower form accuracy. Thus in this study, aiming at the realization of highly efficient and precise grinding of glass lenses, cross grinding of optical glass BK7 is carried out. As a first step of the study, the influence of grinding conditions on the surface quality is investigated experimentally.

X-ray micro-calorimeters such as the Soft X-ray Spectrometer on board ASTRO-H will enable precise spectroscopy of iron K lines. To exploit the full power of the high-energy resolution, X-ray telescopes with a large effective area around 6 keV are essentially important. We designed a Wolter-I X-ray telescope with Ir/C multi- layer mirrors to enhance the effective area at around 6 keV by the principle of Bragg reflection. We assumed a diameter of 110 cm and a focal length of 110 cm for our telescope. Our simulation suggests that the effective area averaged in the 5.7{7.7 keV band could be 2000 cm2.

We fabricated x-ray mirrors from carbon-fiber-reinforced plastic with a tightly nested design for x-ray satellites, using a replication method for the surfaces. We studied the effects of print-through on the mirror surface as a function of curing temperature. With room temperature curing, the root-mean-square value of the surface error was 0.8 nm. The reflectivity was measured using 8-keV x-rays, and the roughness was calculated as 0.5 nm by model fitting-comparable to that of the ASTRO-H/HXT mirror. We verified the long-term stability of the mirror surface over 6 months. We fabricated Wolter type-I quadrant-shell mirrors with a diameter of 200 mm and performed x-ray measurements at BL20B2 in the SPring-8 synchrotron radiation facility. We obtained reflection images of the mirrors using a 20-keV x-ray spot beam with a slit size of 10 × 1 mm in the radial and circumferential directions, respectively. The averaged half-power diameter (HPD) of the images in one mirror was 1.2 arc min in the circumferential center of the mirror and 3.0 arc min at the edge. In the spot images with a smaller slit size of 10 × 0.2 mm, we achieved an HPD of 0.38 arc min in the best case., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: PA1610075000