Direct Three-Dimensional Shape Measurement by Digital Light-in-Flight Holography

Area of Science:

• Optics and Photonics
• Metrology
• Digital Imaging

Background:

• Direct shape measurement is crucial for various industrial and scientific applications.
• Digital holography offers high-resolution 3D reconstruction capabilities.
• Limitations in resolution and optical delay management in existing methods necessitate new approaches.

Purpose of the Study:

• To propose and validate a novel method for direct 3D shape measurement using short laser pulses and digital holography.
• To address the challenge of limited CCD resolution by creating a variable optical delay.
• To enable accurate three-dimensional shape evaluation through holographic reconstruction.

Main Methods:

• An in-line holographic setup utilizing a Littrow configuration with a blazed reflection grating was employed.
• Short laser light pulses were used in conjunction with a CCD array for holographic recording.
• A continuous variation in optical delay across the CCD array was engineered to manage resolution constraints.

Main Results:

• Different sections of the object were reconstructed from distinct regions of the CCD array, corresponding to specific path lengths.
• The proposed method successfully enabled the evaluation of three-dimensional object shapes by integrating these reconstructed sections.
• Both theoretical predictions and experimental data confirmed the efficacy of the developed technique.

Conclusions:

• The presented digital holography method provides an effective means for direct 3D shape measurement.
• The innovative use of a variable optical delay overcomes CCD resolution limitations.
• This technique holds potential for applications requiring precise and efficient 3D metrology.