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1、Wang wensheng 7 1 Automatic hologram calculation7.1 Automatic hologram calculation General characters: All interferometry 1) conventional 2) holographic ()NN+N )gp 3) Automatic holographic Calculating fringes number , from or fi dfind displacement, deformation. Conventional interferometry : smooth r
2、egular surface Such as spherical, plane aspherical(2 order) Measuring difference between Standard and measured wave front Holographic I : roughness, any size and irregular form gpg,yg Automatic I : 2D, 3D, 1D magnitude 、 shape 、 direction high accuracy, high speed processinghigh accuracy, high speed
3、 processing 7 1 Automatic hologram calculation7.1 Automatic hologram calculation 7 1 A tti h lll ti7.1 Automatic hologram calculation 7 2l tih lh7.2 real-time holography theory theory relation between phase and shift vector ()()()() 2 x ykx ykx yLx y = uruu ru r ()()()() 12 ,x ykx ykx yLx y = 1 k ur
4、 uu r : illuminating unit vector 2 k r L u r :observating unit vector Determined by arrangement :displacement vector or called sensitivity vector intensity of interference pattern 00 ( ,)2cos( ,) RR I x yIII Ix y=+ 00 ( ,)2cos( ,) RR I x yIII Ix y+ R I ( , )x y : reconstructed object wave, original
5、state If we find out ( , ) y using 3-step method or 4-step method 7 2 real time holography7.2 real-time holography 1( , ) ( , )( , )cos( , )I x ya x yb x yx y=+ 2( , ) ( , )( , )cos ( , )0Ix ya x yb x yx y=+ 3( , ) ( , )( , )cos ( , )Ix ya x yb x yx y=+ At given point, get 3 intensitygp, gy 31 331 (
6、,) 22 II tgxy ctg III = 90o=1 2 ctg = () ()()yxIyxI, arctan 13 () ()() ()()()yxIyxIyxI yy yx ,2, arctan, 123 13 + = 7 2 real time holography Key elements PZT piezoelectric translator for phase displacement (shifting) 7.2 real-time holography PZT piezoelectric translator for phase displacement (shift
7、ing) BSO crystal for automatic development and 1220 Bi SiO home positionhome position Digital hologram EALCD-CCD TV-Computer system , for automatic processing and controllingcontrolling data processing 1) Bdliiti( llil)1) Boundary limiting (ellipse polygon) 2) Analog/Digital converter FGB (frame Gra
8、bber Board) Hologram CCD-A/D-monitor A/D pixel-Gray level , scanning up-down left-right 7.2 real-time holography experiment setup 7.2 real time holography requirement : In situ developing without home position problemIn-situ developing without home position problem High speed processing, 7.2 real-ti
9、me holography 1. light source Ar+(Argon Laser) gp y Ar(Argon Laser) (continuous wave) CW radiation power 300 mw (5W) lth 0 514wavelength 0.514um within sensitive spectrum of BSO, before power , open water gate first for water cooling, then turn on electric power depower: turn off power first，then wa
10、ter gate 2.shutter2.shutter controlling exposure time. Place it in front of beam splitter shutter-controller-computer f3 thhiftifor 3-sterp phase shifting after exposure shut off the shutter scanning, recording, processing fringes open-close for A/D converter， otherwise the information on BSO will b
11、e erased (eliminated ) in 10 second 7 2 real time holography 3.Beam splitter(half mirror) 7.2 real-time holography O A R A Separate incident light beam Into to beams : 4. attenuator RO II= Amplitude modulation It can be placed in reference OP 5 illitibjti5. illuminating objective Illuminate object w
12、ith uniform brightness Fine adjust micro lens and pinhole 6. measured object Rough object surface : uniformly spray white powder 7. polarizerp Linear polarized light beam is diffused on rough surface , depolarize about 50% Put in polarizer to increases contrast of fringesPut in polarizer to increase
13、s contrast of fringes 7 2 real time holography 8. imaging lens :7.2 real-time holography 8. imaging lens For image hologram , decrease exposure time t 9. recording material BSO crystal 1) automatically 2)real time developBSO crystal 1) automatically 2)real-time develop PTF (photoconductor thermoplas
14、tic film) 10. collimator C llitdd filtth li ht bCollimate expand and filter the light beam Micro lens+ pinhole+ collimator 11. phase controller 1) plane parallel plate 2) piezoelectrical translator PZT+ phase controller +computer ( digital phase shifting) 12. vidicon- computer system : Scanning frin
15、ges A /D converter Processing digital information Get deformated information Display the measured experimental result 7 2 real time holography Measure method (1) Not only record the deformation result 7.2 real-time holography (1) Not only record the deformation result But also record the deformation
16、 process (2) If deformation is too large, fringes Changes too density , kh ibji i i lh ltake the instantaneous object state as new initial zero hologram (as reference) requirement requirement In-situ developing without home position problem High speed processing, Holographic material BSOPTDHolographic m
