Optical measurements of the silicon vacuum window with anti-reflective sub-wavelength structure for ASTE Band 10.

For millimeter and submillimeter-wave astronomy, it is highly desirable to have vacuum windows within the receiver cryostat that exhibit low reflection, low loss, and a wide bandpass. The use of antireflective (AR) sub-wavelength structures (SWSs) on substrates has expanded the possibilities for creating new vacuum windows. Recently, a novel method of fabricating AR SWS on a silicon-on-insulator wafer has been proposed, and a vacuum window with a two-layer AR SWS has been developed for use with the Atacama Submillimeter Telescope Experiment Band 10 receiver.

Analytical expression of aperture efficiency affected by Seidel aberrations.

The effect of aberrations on the aperture efficiency has not been discussed analytically, though aberrations determine the performance of a wide field-of-view system. Expansion of a wavefront error and a feed pattern into a series of the Zernike polynomials enables us to calculate the aperture efficiency. We explicitly show the aperture efficiency affected by the Seidel aberrations and derive the conditions for reducing the effects of the spherical aberration and coma.

Wide field-of-view crossed Dragone optical system using anamorphic aspherical surfaces.

A side-fed crossed Dragone telescope provides a wide field of view. This type of telescope is commonly employed in the measurement of cosmic microwave background polarization, which requires an image-space telecentric telescope with a large focal plane over broadband coverage. We report the design of a wide field-of-view crossed Dragone optical system using anamorphic aspherical surfaces with correction terms up to the 10th order.

Measurement of complex amplitude with a point-diffraction interferometer.

We propose a pupil-plane wavefront sensor to measure instantaneous phase and amplitude aberrations, developing the configuration of the point-diffraction interferometer proposed by Imada et al. [Appl. Opt.

Real-time point-diffraction interferometer and its analytical formulation.

We propose a novel wavefront sensor and study its performance with an analytical formulation. The sensor has a polarizing point-diffraction beam splitter. Using transmitted and reflected beams, we can build a real-time point-diffraction interferometer with high precision and efficiency.