Progress in 2009

1. A High-contrast Coronagraph with a capability to direct image Earth-like planets Jiangpei Dou 1,2,Deqing Ren1,2,3, Yongtian Zhu1,2 , Xi Zhang1,2 1.National Astronomical Observatories/ Nanjing Institute of Astronomical Optics & Technology, China 2. Key Laboratory of Astronomical Optics & Technology, Nanjing Institute of Astronomical Optics & Technology, Chinese Academy of Sciences 3.Physics & Astronomy Department California State University Northridge Progress in 2009 A contrast better than 10-6 results has been achieved at angular distance of 4λ/D. In Process Phase-induced coronagraph with DM Near-Future Plan Direct image the young giant planets and those with long orbits using Ground-based Telescope. Simulation results of phase-induced coronagraph through a DM left: The photograph of the tested filter. Cr film was coated on the upper surface of the glass substrate and an anti-reflection coating was coated on the opposite surface. The clear aperture of the substrate is 62mm x 57mm with a thickness of 10mm. Right: Pinholes and the gap between the last two neighboring steps. Red circles indicate the pinhole on Cr film. Rectangular bar shows the gap between last two neighboring steps. Shape of the filter and the simulated coronagraphic point spread function (PSF) image. The theoretical contrast for one filter apodized coronagraph (solid line) and that without any apodization (doted line). A contrast in the order better than 10-6 should be achieved at an angular distance of 3λ/D in theory. The pupil of the actual telescope and its corresponding PSF. Diffraction by pupil is serious and the extra-solar planets will not be seen. Optical Layout Square Aperture without any apodization, a 10x10 DM is used for simulation Left Figure shows the phase map of the DM to induce for a square aperture; Middle Figure shows the PSF image with a quarter of the whole image plane for a high contrast region; Right Figure shows the corresponding contrast. Latest Laboratory Experiment Results Contrast plot along the diagonal direction. Tested PSF image Based on the 13-step-transmission filter previously designed, a contrast of 10-7 can be received. We use a 10x10 DM to induce a specific phase to gain an extra contrast of 10-3, in which case we can reach a high contrast of 10-10. Such a method is very suitable since it can gain a high contrast in a large working region (depend on the step number rather than that of actuator) and the phase provided by the DM will reduced to a great extent. Meanwhile, the advantage of introducing a DM for the step-transmission based coronagraph is that such a method is no sensitive to broad-band light. Shape of the 29-step Apodizing Filter, Theoretical PSF using this filter and contrast Purchased from BostonMicromachines Corp.，12x12 DM，In progress, WFS interface First light will be expected later this year. Better Result is expected! Speckle Removing techniques Apodized Pupil: consists of two identical transmission filters. In each filter, transmission changes only in one direction. The plot of simulated PSF at the focal plane: 10-10 contrast imaging at 2 /D is achieved in theory. Wave-front sensing Wave-front Controlling Contrast along the diagonal direction Relative Intensity (a) The original wave-front map; (b) the reconstructed wave-front map λ/D Shape of the continuous Apodizing Filter, Theoretical PSF using this filter and contrast plot Ren. et al 2006 ApJ ,640 530   doi:10.1086/500007 Dou. et al, 2009 Science in China Series G-Physics Mechanics Astron , 52(8) 1284 doi: 10.1007/s11433-009-0158-2  Ren et al,2007 PASP,119,1063 ,doi: 10.1086/522015 Dou. et al, 2008 SPIE, Proc. SPIE, Vol. 7010 Correspondence: *Email: jpdou@niaot.ac.cn , ytzhu@niaot.ac.cn, xzhang@niaot.ac.cn; phone: +86-025-85482285 **Email: ren.deqing@csun.edu; phone: 818-677-3186