Parametric plot Noise 4%
Noise 40% Temporal phase steps
Uncalibrated temporal phase stepping in a two-channel
spatially phase stepped speckle interferometer
Delft University of Technology
Faculty of Applied Sciences
90 0 -4 -2 0 2 4 0 100 150 200
phase change (rad)
position
Phase change
IntensitySimulations
90 0 0 120 240 Dj = 0 - 4pMotivation
Phase stepping during dynamic events.
Principle
Three-bucket quadrature phase stepping: Fixed spatial phase step p/2: yields one speckle pattern pair. Temporal phase steps: both speckle patterns in a pair are phase stepped simultaneously, yielding three quadrature pairs.Method
Features
Fixed spatial phase step p/2 : polarisation plane rotator.
Temporal phase steps: rotating l/2 plate, combined with l/4 plate. Object change allowed during temporal phase stepping.
Temporal phase steps can be arbitrary, and even unknown.
Supported by the Technology Foundation STW, applied science division of NWO and the technology program of the Ministry of Economic Affairs.
Peter A.A.M. Somers and Nandini Bhattacharya Optics Research Group, e-mail: p.a.a.m.somers@tnw.tudelft.nl
Ae a b c R I90 I0 A B C D
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2c
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Ae
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-(Heron, 1st century)
2
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Ae abc I = R 4 = 0 500 1000 1500 2000 0 90 180 270 360 step 1 step 2 j I1 - IB = IM cos (j ) I2 - IB = IM sin(j )]
[
- -= B B I I I I 1 2 1 arctan j 1 B C A( )I ,1I2Four-bucket Two-bucket Three-bucket quadrature 1 j IB M I90 I ,0
Processing steps
Acquire 3 temporally phase stepped quadrature pairs. Calculate modulation (I = R) with Herons's formula.
Determine location of D, and calculate background I . Calculate phase j, repeat after phase change.
M B 0 120 240 0 50 100 150 200 250 0 100 150 200 250 I0 90 I 50 0 50 100 150 200 250 0 100 150 200 250 I0 90 I 50 50 250 -4 -2 0 2 4 0 100 150 200
phase change (rad)
position 50 250 0 50100 150 200250 0 50100 150 200250 0 50100 150 200250 0 50100 150 200250 1 1 Parametric plot Phase
