Automatic data reduction of certain holographic interferograms

Area of Science:

• Optical Metrology
• Mechanical Engineering
• Holography

Background:

• Accurate measurement of rigid body displacement is crucial in engineering.
• Traditional methods can be time-consuming or lack precision for micro-displacements.

Purpose of the Study:

• To develop and validate an automated technique using holographic interferometry for precise translation measurement.
• To assess the accuracy and applicability of the method for diffusely reflecting objects.

Main Methods:

• Digitizing photographs of a double-exposed hologram's virtual image.
• Processing data using a CDC 6600 computer to count fringe shifts over image points.
• Varying viewing direction to create displacement contours with 0.0368 cm surface resolution.

Main Results:

• Successfully verified a 6.35-microm linear displacement of a 3.68-cm diameter aluminum object.
• Achieved an error of less than or equal to 4.3% across the entire object surface.
• Demonstrated the feasibility of contour generation based on fringe movement.

Conclusions:

• The automated holographic interferometry technique provides accurate displacement measurements.
• The method shows promise for extension to the analysis of three-dimensional objects.
• This technique offers a precise and potentially automated solution for metrology challenges.