Three-dimensional optical coherence digital-null deformography of multi-refractive-surface optics with nanometer...

Area of Science:

• Optical Engineering
• Metrology
• Materials Science

Background:

• Lens deformation during reliability testing is critical for design and fabrication.
• Measuring nanoscale changes on refractive lens surfaces is challenging due to optical path distortion.

Purpose of the Study:

• To develop a method for simultaneously measuring nanoscale, test-induced changes on all refractive lens surfaces.
• To overcome the challenge of refractive distortion in optical path measurements.

Main Methods:

• Developed Optical Coherence Digital-Null Deformography (ODD).
• Utilized phase-sensitive Optical Coherence Tomography (OCT) for digital null recording.
• Employed digital null alignment (DNA) with a hexapod for iterative physical alignment.
• Measured changes using intensity centroid shift (ICS) and joint wavenumber (k)-depth (z) domain phase shift (kz-PhS).

Main Results:

• The kz-PhS method demonstrated a sensitivity of 4.15 nm and a range of 5 µm.
• DNA achieved high precision: 0.04 µm (z-translation), 0.24 µm (x/y-translation), 0.0003° (tilt), and 0.03° (rotation).
• ODD successfully visualized non-destructive, simultaneous changes on all refractive surfaces during a lens drop test.

Conclusions:

• ODD effectively circumvents refractive distortion for accurate lens deformation measurement.
• The technique facilitates non-destructive, simultaneous visualization of nanoscale changes on multiple lens surfaces.
• ODD is a valuable tool for advancing lens design and fabrication reliability testing.