Mikio Kurita

ABSTRACT An overview of the Seimei telescope, a 3.8 m optical infrared telescope located on Mt. Chikurinji in the Okayama prefecture of Japan, is presented. Seimei is a segmented-mirror telescope whose primary mirror consists of 18 petal-shaped segments. The telescope tube supporting the thin segmented mirrors is structurally incorporated within large arc-rails providing the elevation axis. The tube has a light-weight homologous structure designed with a genetic algorithm. The total weight of th

We designed the optics supporting structure (OSS) of a 3.8 m segmented mirror telescope by applying genetic algorithm optimization. The telescope is the first segmented mirror telescope in Japan whose primary mirror consists of 18 petal shaped segment mirrors. The whole mirror is supported by 54 actuators (3 actuators per each segment). In order to realize light-weight and stiff telescope structure, we have adopted full truss structure as OSS of the telescope. We optimized its design by a newly

We developed the improved three-point method as measuring machine that is applicable for measurements of various telescope optics, including concave, convex, and off-axis mirrors of high aspheric. The method is small and robust against temperature change and vibration and can extend a conventional machining tool to a measurement tool. We measured the cross section of a flat mirror of ϕ 300 mm with this method on an old milling machine. The result was consistent with that obtained with an interfe

A key technique in direct imaging of extrasolar planets with ground-based telescopes is extreme adaptive optics. It requires a wavefront sensor capable of achieving high accuracy with a small number of photons. Imada et al. [Appl. Opt.54, 7870 (2015)APOPAI0003-693510.1364/AO.54.007870] proposed a type of wavefront sensor that employs a point-diffraction interferometer (PDI). This type of sensor has problems concerning a low photon-usage efficiency and manufacturing feasibility. In addition, they

Data-stitching algorithms are widely used to combine multiple sequential data or extend the working area of measurement systems. However, stitched data by the least squares method have inconsistency at the intersections due to their measurement errors, mainly drift error. We propose a new stitching algorithm, to the best of our knowledge, that considers sequential data as an elastic body. We examine the algorithm with several types of sequential data and confirm mitigating of error of drift.

We report a new manufacturing system for free-form large optics. The system enables both polishing and test on an optical surface by a robot arm. The robot arm drags sensors on the surface for measuring cross sections over the test surface. A new algorithm stitches the cross-sectional data to the two dimensional surface shape with improving the accuracy simultaneously. We used the system for an aspheric convex mirror (1 m in diameter) and a flat mirror (major axis of 1m); they are secondary and

We have developed a transportable, lightweight telescope mount. It is capable of carrying a primary mirror of up to 2.5 m in diameter, but is only 7 m high and weighs 5 tons, approximately one-fifth the weight of a conventional telescope. We measured the pointing and the tracking accuracies to be better than 3'' and 0''.5 for 10 minutes, for pointing and tracking, respectively. We have demonstrated that the telescope is readily transportable while retaining sufficient accuracy for astronomical o

We are developing an ultra-lightweight and inexpensive mid-sized telescope on an alt-azimuth mount. Utilizing commercially available truss elements and compact high precision bearings we are able to achieve significant weight and cost savings while maintaining mechanical strength and stability. The design features a structure integrating the mirror-cell and the altitude bearing's arc-rails coupled to a short-armed fork through R-Guide bearings. The fork sits on a turn-table providing rotation ab