光干涉课题进展.ppt

Background Goal Dream: Optical long baseline interferometer based in space Reality: Optical interferometry of China is just in inital stage + limited money Option: Compact Fizeau Space Interferometer short baseline direct instantaneous imaging small scale Step 1: gound prototype with diameter equivalent to 1m Step 2: Fizeau space Interferometer with diameter equivalent to 2~4m future: longer baseline more elements... Array configuration Geometric Array Beam combining errors (1/2) PSF vs. piston error Beam combining errors (2/2) PSF vs. tip/tilt error Spec. of the ground prototype Y-4 array ----- (1) high stability due to symmetric structure (2) optimal MTF (3) tubes modulization common mounting ----- without optical delay line for compensating outer OPD C-shape board triangle flatform ----- high stiffness resonance freq. wide FOV ~ ±2 Direct Drive ----- no backlash, high tracking accuracy ~ RMS:0.01(Dec=45°) FEA of structure Optics design Challenge How to measure and eliminate co-phasing errors between sub-telescopes? pyramid wavefront sensor fringe tracking How to improve image quality? interferometric image restoration method - better MTF Conceptual Design of a Compact Fizeau Interferometer Neng-hong Zhu, Xin-yang Chen Shanghai Astronomical Observatory * Modulation Transfer Function: MTF=|FT(PSF)| α=0° α=10° α=20° α=30° piston=-0.2λ piston=-0.4λ piston=0.2λ piston=0.4λ MTF vs. piston Strehl Ratio vs. piston SR≥0.9 ----- piston P-V≤0.1λ [Cao Fang, et al, 2008] X tip=0 （a）Y Tilt Error=0 （b）Y Tilt Error=0.1λ (c）Y Tilt Error=0.2λ (d) Y Tilt Error=0.3λ X tip=0.2λ X tip=0.1λ X tip=0.3λ Y tilt=0 Y tilt=0.2λ Y tilt=0.1λ Y tilt=0.3λ MTF vs. tip/tilt Strel Ratio vs. tip/tilt SR≥0.9 ----- tip/tilt P-V≤0.055λ≈0.3 [Cao Fang, et al, 2008] sub-telescope optics folding combiner optics confusion circle Φ≤ 0.7 Primary mirror Outer diameter(mm) 420 Inner diameter(mm) 80 Thickness