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ENERGY

ENERGY. h n. a proposal for a M ulti-channel C mos C amera. e-. F. Pedichini, A. Di Paola, R. Speziali INAF Oss. Astr. Roma. What is multi-channel imaging?. The most standard duty of an astronomer simply : Multi Band Photometry. How to do it?. The 3 most used technologies:.

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ENERGY

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  1. ENERGY hn a proposal for a Multi-channel Cmos Camera e- F. Pedichini, A. Di Paola, R. Speziali INAF Oss. Astr. Roma

  2. What is multi-channel imaging? The most standard duty of an astronomer simply : Multi Band Photometry How to do it?

  3. The 3 most used technologies: • 1- an old, but good, FILTER WHEEL + 1 CCD imager • 2- a MOSAIC FILTERED CCD imager • 3- a DICROICH focal plane splitter + several CCD imagers All of these items deserve a... deep comparative analisys !

  4. an old, but good, FILTER WHEEL + 1 CCD imager ...101010 00111.... Imager Has been used since the first digital imager, with great results, low cost, simple mechanics, user selectable bands and thx. to modern CCDs also a very good Q.E. ......but...... different bands are exposed and acquired at different times due to detector readout time and filters set up time

  5. a MOSAIC FILTERED CCD imager matrix filter ....RGBRGB.... widely used in low cost tv cameras, digital photography apparatus and amateur astronomy color imagers with all the bands taken during the same exposure .....but..... no user selectable bands, low Q.E. (quite impossible to be used with back illuminated detectors) and the bad MOIRE effect...

  6. the MOIRE effect... the color of each pixel is function of the signals of the nearest ones producing nice on sharp edges....! RAINBOWS astronomers dont’LIKE!

  7. a DICROICH focal plane splitter + several CCD imagers ...101010 00111.... Imager ...101010 00111.... Imager sometime used in astronomy with the best Q.E. and time sincronicity in each channel ....but.... complex, expensive and polarization &f# sensitive ...101010 00111.... Imager

  8. polarization &f# sensitive • dicroichs are made up by dielectric layers and partially polarize the reflected and transmitted beams • best performances about field uniformity need collimated beams so a collimator and several camera optics must be added in the imager optical train • often the weight and size of a “dicroich” imager make it impossible to fit some telescope focal planes as in the case of Schmidts or fast prime foci and now we go to a comparative table...

  9. comparative table.... ........is the world of C-MOS helping us with a fourth chance?

  10. http://www.foveon.com in this detector each pixel outputs R,G and B signals with all the nice features of a CMOS “on chip camera” • about 10Mpix in three layers • low power • on chip 12bit ADC • windowing and binning • 4 f.p.s. • less than 30e- RON

  11. foveon phisycs:on silicon “dicroich” • red photons are deep penetrating the silicon • green photons make photoelectrons midway • blue photons interact early.....

  12. foveon bands: • bands are not user selectable • how do they compare to Johnson filters • what can we do with them in astronomy?

  13. Black Bodies simulations: BB spectra from 2000 to 20000 K convolved with BVR Jhonson and BVR Foveon converted to magnitudes

  14. reduction to Johnson.... it is possible using instr. color index Vf-Rf or Bf-Vf and a second order polinomya. error is 0.01 mag. V-Vf = 0.7818(Vf-Rf)^2 + 0.2571 (Vf-Rf)- 0.0051

  15. Energy camera: Uses Foveon M10 x3 CMOS 2200 x 1500, 9 micron pixels 3 bands, 4fps about 25 arcmin2 @ 12 m focal lenght 0.15 arcsec/pixel 30 e-RON 0.25 seconds read out time no shutter needed

  16. LBC comparison on a mag 14 star: Target: star field BVR fast photometry at S/N = 100 to detect light transients SKY 1”seeing ~21mag/arcesc^2 Telescope: Mirror 8.2m. 1.4F# (prime focus camera) Both cameras: 9 micron pixels about 4Mpixel CCD: exp. 0.013 sec QE 90% 2e/adu RON 5 e- Time for 3 bands: exp. 3x0.013 sec filter 3x1 sec readout 3x1sec total ~3 sec Energy: exp. 0.04 sec QE 30% 5e/adu RON 30 e- Time for 3 bands: exp. 1x0.04 sec filter 0 sec readout 1x0.25sec total ~0.3 sec

  17. LBC comparison on mags @ S/N 100: 3.9Hz 3.5Hz CCD exp Energy exp 2.9Hz 2Hz 1.1Hz 0.5Hz Mag

  18. ENERGY @ 60/90/180 Schmidt: On a smaller telescope at the resolution of 1”/pixel the field is 1180 arcmin^2. Energy becomes a: multiband GRB Hunter on raw satellite triggers Hz S/N=100 S/N=10 Mag

  19. 2nd comparative table....

  20. open discussions: • 1) Is it useful in astronomy? • 2) Can Foveon modify the shape of the bands? • 3) Will we have more than 3 on-chip bands in the future? • 4) Can Foveon technology used on back ill. detectors? • 5) Can Foveon technology join CCDs?

  21. the end.....Energyis a Multi channel camera or... Mc2

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