1. “TUNABLE FILTER TECNIQUE :” A phase ambiguity solution with PYramid Phasing Sensor (PYPS)

2. Technological development for the ELTs ONE OF THE KEY ACTIVITIES: PHASING AND ALIGNMENT OF THE PRIMARY MIRROR SEGMENTS ARE CORRECTED SIMULTANEOUSLY tip tilt piston errors of segmented mirror P yramid W avefront S ensor: 2005 closed loop

3. PYramid Phasing Sensor (PYPS) Based on the sensing of phase step On the segment edges !! limitation of signal ambiguity introduced by the phase periodicity  ambiguity mirror surface step wavelenght used for the sensing PYPS signal

4. 3 TECNIQUES THAT ALLOW TO SOLVE THE PHASE AMBIGUITY WITH PYPS  two wavelenght closed loop  wavelenght sweep tecnique (WST)  segment sweep tecnique (SST) main task for an optical phasing sensor: to keep phased the segments sensor: to keep phased the segments during the observation during the observation PYPS tip tilt piston errors correction simoultaneously this has been done operating PYPS in closed loop source    nm

5. 3 TECNIQUES THAT ALLOW TO SOLVE THE PHASE AMBIGUITY WITH PYPS  two wavelenght closed loop  wavelenght sweep tecnique (WST)  segment sweep tecnique (SST) main task for an optica phasing sensor to keep phased the segments to keep phased the segments during the observation during the observation PYPS tip tilt piston errors correction simoultaneously this has been done operating PYPS in closed loop source    nm open loop mode: sine function   2  2] not phase ambiguity closed loop mode: extended to   ] around sinus zero in this range the function of sin is preserved! -- ++ +  2 -  2 0

6. 3 TECNIQUES THAT ALLOW TO SOLVE THE PHASE AMBIGUITY WITH PYPS  two wavelenght closed loop  wavelenght sweep tecnique (WST)  segment sweep tecnique (SST) main task for an optica phasing sensor to keep phased the segments to keep phased the segments during the observation during the observation PYPS tip tilt piston errors correction simoultaneously this has been done operating PYPS in closed loop source    nm open loop mode: sine function   2  2] not phase ambiguity closed loop mode: extended to   ] around sinus zero in this range the function of sin is preserved! -- ++ +  2 -  2 0 °

7. 3 TECNIQUES THAT ALLOW TO SOLVE THE PHASE AMBIGUITY WITH PYPS  two wavelenght closed loop  wavelenght sweep tecnique (WST)  segment sweep tecnique (SST) main task for an optica phasing sensor to keep phased the segments to keep phased the segments during the observation during the observation PYPS tip tilt piston errors correction simoultaneously this has been done operating PYPS in closed loop source    nm open loop mode: sine function   2  2] not phase ambiguity closed loop mode: extended to   ] around sinus zero in this range the function of sin is preserved! -- ++ +  2 -  2 0 °°

8. 3 TECNIQUES THAT ALLOW TO SOLVE THE PHASE AMBIGUITY WITH PYPS  two wavelenght closed loop  wavelenght sweep tecnique (WST)  segment sweep tecnique (SST) main task for an optica phasing sensor to keep phased the segments to keep phased the segments during the observation during the observation PYPS tip tilt piston errors correction simoultaneously this has been done operating PYPS in closed loop source    nm open loop mode: sine function   2  2] not phase ambiguity closed loop mode: extended to   ] around sinus zero in this range the function of sin is preserved! -- ++ +  2 -  2 0 °° ° The closed loop operation is able to drive the actuator to the same position (it works with iteraction process)

9. 3 TECNIQUES THAT ALLOW TO SOLVE THE PHASE AMBIGUITY WITH PYPS  two wavelenght closed loop  wavelenght sweep tecnique (WST)  segment sweep tecnique (SST) main task for an optica phasing sensor to keep phased the segments to keep phased the segments during the observation during the observation PYPS tip tilt piston errors correction simoultaneously this has been done operating PYPS in closed loop source    nm Interaction matrix Reference acquisition ( required:FIRST FLAT ) in order to operate in closed loop mode:

10. To obtain the condition in order to employed PYPS in standard co-phasing tecnique Piston error in +/-  New tecnique : NO C-LOOP Wavelenght Sweep Tecnique Segment Sweep Tecnique Calibration NOT required -> Segment are driven in to 500nm range (accuracy) -> Capture range +/-13  m -> parallel procedure -> hight accuracy -> capture range infinite -> one segment as reference And sweeping the neightbors C-loop calibration FAST!!!

11. To obtain the condition in order to employed PYPS in standard co-phasing tecnique Piston error in +/-  FIRST FLAT CO-PHASING Wavelenght Sweep Tecnique Segment Sweep Tecnique Calibration NOT required -> Segment are driven in to 500nm range (accuracy) -> Capture range +/-13  m -> parallel procedure -> hight accuracy -> capture range infinite -> one segment as reference And sweeping the neightbors C-loop calibration First method Second method FIRST FLAT ACHIEVED!!!!

12. ABOUT W AVELENGHT S WEEP T ECNIQUE Based on piston signal dependence of the wavelenght S = S(1/ ) Mesuring signal for several value of WE CAN FIT S(1/ ) this mesurement gives an extimation of the physical step that lies on the considered sensor sub-aperture WE CAN USE A TUNABLE FILTER

13. Liquid crystal tunable filter Narrow-bandwith Uses electronically controlled liquid crystal elements in a Lyot-type birefringent design to select a transmitted wavelenght range while blocking all others. quartz Glass substrate Liquid crystal Sheet polarizer Lyot-type filter VARYNG THE GAP SELECT

14. fff T f +P f f 22 + WORKING LIMITS the capture range is defined by the resolution of the wavelength sweep. T is suppose to be positive we found : 2|d | f Minimum step:  m ~ 500 nm Maximum step:  M ~ 80  m 1 The expected values for Pf are: 0 when d >0  when d <0

15. ...future project about this tecnique is in APE project and at the WHT collaboration with the WHT group.... TUNABLE FILTER ELTsCO-PHASING “MAIN SCIENTIFIC CASES”

16. ...future project about this tecnique is in APE project and at the WHT collaboration with the WHT group.... TUNABLE FILTER ELTsCO-PHASING “MAIN SCIENTIFIC CASES” Exo-Planetary Systems and evolution

17. ...future project about this tecnique is in APE project and at the WHT collaboration with the WHT group.... TUNABLE FILTER ELTsCO-PHASING “MAIN SCIENTIFIC CASES” Exo-Planetary Systems and evolution Star Formation and Stellar Discs Dark Matte and Dark Energy Galaxies and Cosmology GRBs Black Holes, AGN and QSOs THE UNEXPECTED…….

18. Liquid crystal tunable filter Narrow-bandwith Uses electronically controlled liquid crystal elements in a Lyot-type birefringent design to select a transmitted wavelenght range while blocking all others. quartz Glass substrate Liquid crystal Sheet polarizer Lyot-type filter There are multy-plate filters, and each plate being half the thickness of the previous one. Only wavelenght at which the ordinary and extraordinary rays have optycal path lenghts equal to an integer multyple of the wavelenght exit the plates in the same polarization state as they entered thje plates. The separation and narrowness of the transmission peacks depends on the number, thickness,and orientation of the plates

19. Layot-filter Optical filter is composed of a crystal birefrangent plane (usually quartz) that is interposed bween two parallel polarizer (inclined at 45° from optic axis of the plate): 1)Wave hit the polarizator 2)Wave is splitted in to two component: ordinary an extraordinary rays 3)The two wave’s component have got different refraction index: they are a phase shift between (that dipends of plate’s thickness and crystal’s birefringent) 4)The two wave’s component are put together on the output polarizator, and becouse of they inteference, they realized a transmission 5)A series of these layot-filter close each other allow us to select the output wavelwnght.