Tympanic membrane contour measurement with two source positions in digital holographic interferometry

Area of Science:

• Biomedical Optics
• Optical Metrology
• Audiology

Background:

• Quantitative displacement measurement requires accurate object shape data.
• Non-invasive optical testing is valuable in industrial and biomedical research.
• Understanding tympanic membrane (TM) mechanics is key to comprehending the hearing process.

Purpose of the Study:

• To measure the surface contour of ex-vivo cat tympanic membranes (TMs).
• To combine TM shape and displacement data for a complete deformation analysis.
• To investigate the potential of digital holographic interferometry (DHI) for TM analysis.

Main Methods:

• Digital holographic interferometry (DHI) was employed.
• A two-illumination positions method was utilized for shape measurement.
• Digital Fourier transform methods were used to analyze phase changes.

Main Results:

• The TM shape was successfully measured using DHI with two source positions.
• The tympanic membrane was found to have a conical shape.
• A maximum TM depth of 2 mm was measured, with a setup capable of measuring up to 7 mm.

Conclusions:

• TM shape data, combined with displacement data, offers a comprehensive description of TM deformation.
• Acquiring knowledge of TM shape reveals mechanical behavior and potential physiological alterations.
• This method provides insights into middle ear diseases and their impact on sound transmission.