Industrial
Inspection
Digital
Holographic Microscopy for Industrial Inspection and Metrology
High-Resolution
Surface Imaging Using Optical Phase  Researchers
at ORNL have developed and patented a direct-to-digital holographic
imaging technology and prototype system for the inspection and metrology
of surface topology and structure. This method records the complex
wave-front of an object directly on the surface of a charge coupled
device (CCD) camera in a single digital image. Unlike phase-shifting
profilometry methods, the phase and amplitude of the imaged object
surface can be determined rapidly from a single digital image at
high throughput using side-band (heterodyned) analysis. The phase
information is directly proportional to the structural topology
(e.g., surface height) and the index of refraction of the various
materials composing the surface.
Base
Technology
 The
prototype ORNL inspection tool uses a 532-nm laser and can resolve
266-nm in the plane of the object surface while resolving 5-nm to
10-nm in the direction of the surface normal (i.e., approximately
l/100). The system can detect height differences from pixel-to-pixel
on the order of 266-nm (i.e., approximately l /2). The prototype
tool currently processes approximately 3 frames per second (fps)
at 1024x1024 pixels x 12 bits on a standard dual 850-MHz processor
Pentium PC (~240Mflops) but could achieve 5 GFlops (15fps) to 10
Gflops (30fps) at 2048x2048 pixels using a dedicated array processing
architecture.
Specifications
and Features
- Source,
532-nm laser
- Windows
OS, Visual C++ software library
- Precision
Newport stage (20-nm accuracy)
- Automation
software to facilitate large area, referential scans
Fact
Sheet available here in PDF format.
Point
of Contact:
Kenneth W. Tobin, Ph.D.
Group Leader, Image Science & Machine Vision
Engineering Science and Technology Division
Oak Ridge National Laboratory
P.O. Box 2008, MS-6010
Oak Ridge, Tennessee 37831-6010
Office: (865) 574-8521
E-mail: tobinkwjr@ornl.gov |
