Mr. Kenta Fujita Profile

Kenta Fujita

at Kobe Univ

SPIE Involvement:

Author

Publications (3)

Proceedings Article | 19 September 2007 Paper

Coronagraph project with the SPICA mission

K. Enya, L. Abe, S. Tanaka, K. Haze, M. Venet, T. Nakagawa, H. Kataza, M. Tamura, J. Nishikawa, N. Murakami, K. Fujita, Y. Itoh, O. Guyon, E. Pluzhnik, T. Wakayama, T. Sato, N. Nakagiri

Proceedings Volume 6693, 66930I (2007) https://doi.org/10.1117/12.733707

KEYWORDS: Coronagraphy, Space telescopes, Telescopes, Point spread functions, Mirrors, Infrared telescopes, Binary data, James Webb Space Telescope, Photomasks, Wavefronts

Read Abstract +

We present the status of the development of a coronagraph for the Space Infrared telescope for Cosmology and Astrophysics (SPICA). SPICA is the next generation of infrared space-borne telescope missions following to AKARI, led by Japan. SPICA will carry a telescope that has a 3.5 m diameter monolithic primary mirror and the whole telescope will be cooled to 4.5 K. It is planned to launch SPICA into the sun-earth L2 libration halo orbit using H II-A rocket in the middle of the 2010s and execute infrared observations at wavelengths mainly between 5 and 200 micron. The SPICA mission gives us a unique opportunity for coronagraph observations, because of the large telescope aperture, the simple pupil shape, the capability of infrared observations from space, and the early launch. We have started development of the SPICA coronagraph in which the primary target is direct observation of extra-solar Jovian planets. The main wavelengths of observation, the required contrast and the inner working angle (IWA) of the SPICA coronagraph instrument are set to be 5-27 micron, 10^-6, and a few λ/D (and as small as possible), respectively, in which λ is the observation wavelength and D is the diameter of the telescope aperture (3.5m). We focused on a coronagraph with a binary shaped pupil mask as the primary candidate for SPICA because of its feasibility. Nano-fabrication technology using electron beam lithography was applied to manufacture a high precision mask and a laboratory experiment with a He-Ne laser (λ=632.8nm) was performed in air without active wavefront control. The raw contrast derived from the average measured in the dark region reached 6.7×10^-8. On the other hand, a study of Phase Induced Amplitude Apodization (PIAA) was started in an attempt to achieve higher performance, i.e., smaller IWA and higher throughput. A hybrid solution using PIAA and a shaped pupil mask was proposed. A laboratory experiment was performed using a He- Ne laser with active wavefront control via a 32×32 channel deformable mirror. A raw contrast of 6.5×10^-7 was achieved. Designs of binary shaped pupil mask are presented for the actual SPICA pupil which is obstructed by the telescope's secondary mirror and its support. Subtraction of point spread function (PSF) was also evaluated.

Proceedings Article | 7 July 2006 Paper

Development of an MIR coronagraph for the SPICA mission

Keigo Enya, Shinichiro Tanaka, Takao Nakagawa, Hirokazu Kataza, Lyu Abe, Motohide Tamura, Jun Nishikawa, Naoshi Murakami, Kenta Fujita, Yoich Itoh

Proceedings Volume 6265, 626536 (2006) https://doi.org/10.1117/12.670976

KEYWORDS: Coronagraphy, Space telescopes, Telescopes, Infrared telescopes, Mirrors, Point spread functions, Mid-IR, Infrared radiation, Planets, Binary data

Read Abstract +

Proceedings Article | 29 June 2006 Paper

Development of simultaneous imaging polarimeter

Kenta Fujita, Maiko Nishida, Yoichi Itoh, Tadashi Mukai

Proceedings Volume 6269, 62693D (2006) https://doi.org/10.1117/12.670232

KEYWORDS: Polarimetry, Polarization, Prisms, Beam splitters, Wave plates, Telescopes, Stars, Astronomy, Calibration, Cameras

Read Abstract +

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years