PhaseCam NASA Tech Days May 2001 James Millerd

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PhaseCamNASA Tech DaysMay 2001James Millerd

• Flatness System
• Overview of Operation
• Measurement of Telescope Mirrors
• Recording of Phase Movies
• Multi-wavelength System
• Overview of Operation
• Measurement of polished and unpolished
  substrates
• Conclusion

www.4dvt.com
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PhaseCam
Instantaneous optical phase measurement. Now
you can make precise interferometric measurements
on.. The Factory Floor
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PhaseCam Operation

• Patent pending optical system
• Spatial phase shift interferometry
• 4 identical interferograms - single CCD sensor
  array.
• Relative phase shift via a quadrant mask
• Compact and easy to align
• Insensitive to motion of the detector array
• simplified camera interface requirement

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Twyman-Green Configuration
PhaseCam
Test mirror
Coupling optic
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PhaseCam - Flatness
Hard disk platters Mirrors/Optics
Wafers
Vibration insensitive Small
footprint Patent Pending
3rd party SW compatibility
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PhaseCam Performance

• Measurement Time
• 2 microseconds per image (electronic gating)
• Nanoseconds with pulsed laser
• Spatial Resolution (x,y)
• 470 x 470 pixels (FOV scalable)
• Vertical Resolution (z)
• 1.2 nanometers
• l/300 repeatability

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NASA 0.5 meter mirror 20 meter standoff 5 nm
repeatability (in air)
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Disk Platter Flatness

• Measured on Factory Floor
• No vibration isolation
• All stages of process
• Wet
• Stains

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PhaseCam Recording of Phase Movies

• Quantitative interferometry at full video frame
  rates
• High speed cameras for ultra-high capture rate

Recorded deflection of hard drive transducer
suspension assembly (TSA)
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PhaseCam - 3D

• Instantaneous phase multi-wavelength
• Replace laser with dual or tunable source
• Dynamic range extended to centimeters
• Specular and diffuse surfaces
• Step height resolved

Detail of US penny shows 1 ?m profiling resolution
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Two-Wavelength Measurement
Df1,2(x,y)
object beam
I cos 4p Dz fr
l1,2
Dz
l2
l1
reference beam
Df2(x,y) - Df1(x,y) 4p Dl Dz 4p Dz
Measure profile
l2
ls
synthetic wavelength (tunable)
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Measurement of polished and unpolished substrates
Single l phasemap
Dual l phasemap
Polished Al 1 mm thick
True 3D measurement
Un-polished diffuse surface
l/2
Discontinuity resolved 1 fringe 3 mm
Discontinuities not resolved Diffuse surface -
random phase Unwrapping errors
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Conclusion
PhaseCam is

• Vibration insensitive, quantitative
  interferometer
• 1 Color system
• Surface figure measurement (nm resolution)
• Snap shot of surface phase
• Acquisition of phase movies
• Multi-wavelength system
• Synthetic wavelength interferometry
• Extends range to centimeters
• Diffuse and specular surface measurement
• Resolves step discontinuties

Useful tool for measurement of next generation
telescopes
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James Millerd 4D Vision Technology, Inc. 17900
Skypark Cir. 103 Irvine, CA 92614 (949)
477-2320 james.millerd_at_4dvt.com