Ph. D Dissertation, the University of Tokyo, 2000.
Subaru Telescope Preprint and Reprint Series, No. 101, ISSN 1344-834X.
PDF version of the thesis can be downloaded from here (PDF3.0, 5.9MB, June 11, 2000).
Optical design: Zemax files
We have constructed a Mid-Infrared Test Observation System, MIRTOS to observe diaction limited structures of mid-infrared sources using the Japanese National Large Telescope, Subaru. Figure 0.1 shows the MIRTOS mounted on the Subaru telescope with other instruments in Cassegrain automated instrument exchanger CIAX-3 (Usuda, et al., 2000).
The system combines two cameras. One is for mid-infrared (MIR, wavelengths of 8-13 microns and 20 microns) and the other for near-infrared (NIR, wavelengths of 1-2.5 microns). They take simultaneous images at a rate more than 10 frames for a second that is fast enough to freeze the atmospheric seeing. The NIR images are not only for the spectral coverage but for reference sources of Two-Wavelength Shift-and-Add (TWSAA), a method that we developed to preserve diaction-limited angular resolution of MIR images during a long integration time. Also it has telescope emissivity mapping mode that images the telescope entrance pupil to determine temperature and emissivity of the telescope and also helps to align the system with the telescope.
For the MIR camera, a Si:As Impurity Band Conduction (IBC) array with 320 by 240 pixels made by Raytheon, Santa Barbara Research Center (SBRC) is used with a pixel scale of 0.067 arcsec, which has enough sampling rate for diaction limited images at 8 microns with a eld of view (FOV) of 21 arcsec by 16 arcsec. For the NIR camera, an SBRC InSb array with 256 by 256 pixels is used. With the pixel scale of 0.028 arcsec per pixel, the NIR camera is optimized to detect positions of the brightest speckle in images at the wavelength of 2.2 microns. It has a FOV of 7.1 arcsec square inside a corner of the MIR FOV to image a reference point source. Both of the imaging optics, which were designed, assembled, and adjusted by us, are re ective optics to cover the wide range of the wavelengths. For MIR, four-mirror optics with a parallel beam section has been made for future installation of a Fabry-Perot. For NIR, three-mirror system was employed to make the optics smaller with enough image quality.
To test the instrument, we observed some of sources including an asteroid (1) Ceres and the central region of NGC 1068 on the Subaru Telescope, along with the entrance pupil of the telescope. In the image of the entrance pupil, we have found hot regions that are planned to be covered by re ecting plates. Image motion of Ceres had a correlation between K'-band and 10 um or 18.5 um, which assures the ect of TWSAA method. In Shift-and-Add images of NGC 1068 taken with 10 um filters along with a 18.5 um filter and a K'-band filter, we see some of components around the central engine of the galaxy. After deconvolution, we see the central structures of the Seyfert 2 galaxy including elongation of the central engine along north-south direction and a mark of hot disk in the east and west of the central peak that is presumably from the torus around the AGN. Also we found silicate emission region at the end of the radio jet observed in 5GHz by Gallimore, et al. (1996).