1. PALM-3000 HOWFS Design Update 2/27/08 C. Baranec Pasadena, CA February 27 th 2008

2. PALM-3000 2 Conceptual design Diffraction effects Other issues Conclusions / Future work

3. PALM-3000 Conceptual Design 1 Decided on system of exchanging lenslet arrays 3 Collimation lens OAP2 focus Lenslet array Reimaging lens CCD Swap out lenslet arrays. Each has the same pupil diameter, but different focal lengths.

4. PALM-3000 Conceptual Design 2 Identified plate scales at different sampling modes (x64, x32, x16, x8) 4 PupilSpot Sizes (arcsec) Desired PS NGSLGSPlanets ’’/pixel (bin) 641.8-2.3 321.52.14(3.5/2.7) 1.3, 2.6 (2) 161.332.04 1.3 (2), 1.95 (3) 81.282.01 1.3 (4), 1.95 (6) Extended Sources 3.5Uranus32x32NGSwant 4x4sampling 2.7Neptune

5. PALM-3000 Diffraction effects Required lenslet arrays for x64 and x32 sampling, low Fresnel number (FN<1), lower than any other operating or planned AO system Issue with ‘focal length’ in low FN resolved Currently simulating impact of crosstalk (finishing in next two weeks) Have setup lab experiment to verify simulations of intensity distribution behind lenslet arrays 5

6. PALM-3000 Simulation and Reality 6 P3K 616nm FN=0.66 Lab exp 808nm FN~0.69

7. PALM-3000 Crosstalk effects Insert movie here 7

8. PALM-3000 Center of Mass (COM) response P3K x64 Transfer curve for the tilted central subaperture Plate scale: 1 pix = 2.1” Subaperture size: 2x2 pixels 8

9. PALM-3000 Crosstalk on adjacent slopes 9 Crosstalk: a ~10-14% effect on adjacent slopes for P3K x64 Estimating up to an additional 10% in RMS WFE

10. PALM-3000 Other issues 10 CCD characterization – namely dark current and its affect on binning chip to get desired plate scales, especially in x8 mode where we will be using faint NGS Refined optical design – currently paraxial Design relay Collimation lens Lenslet arrays – quotes from MEMSoptical, Wavefront sciences, Vitrum

11. PALM-3000 Conclusions / Future work Continuing characterization of crosstalk in simulation –Exact amount of additional reconstruction error? –Mitigation strategies (short-pass filter, less subapertures) Finalization of optical system design Schedule – preliminary optical design by mid-April Obtaining SURF student to help assemble/align/characterize system during the summer. Poster on P3K WFS for SPIE 11