Non-planar calibration phantoms for optical coherence tomography

Abstract

Optical coherence tomography (OCT) is increasingly used in areas such as ophthalmology and contact lens metrology. However, in such cases, image distortion can occur due to the non-planar nature of the measured sample. Postprocessing algorithms can be implemented to correct this distortion. Here we present an OCT phantom designed to confirm the validity of post-processing algorithms used for measuring curved surfaces. A multi-purpose OCT phantom has been created within a fused silica plano-convex lens using the direct femtosecond laser writing technique. This phantom can be used to calibrate and quantitatively assess the performance (e.g. resolution, sensitivity and distortion) of OCT systems and associated post-processing algorithms for curved structures such as lenses. This novel OCT phantom has been characterized using an optical microscope and OCT systems.

Simple Characterization Scheme for Optical Coherence Tomography Systems With Application to a Commercial and a Near-Isometric Resolution Fibre-Based System

“…Whereas the commercial phantom provides good repeatability of geometric structures and allows characterizing the PSF on inscribed reflectors and different depth positions, it would not allow direct measurement of the axial resolution limits as it would be difficult to provide embedded reflecting structures with known size and sufficient accuracy. Laser inscription of structures into fused silica is a favoured method in laboratories that have suitable laser equipment and expertise to create phantoms with known structures [39]. Also, the air wedge using standard microscope slides will not be able to provide high accuracy.…”

Pragmatic Micrometre to Millimetre Calibration Using Multiple Methods for Low-Coherence Interferometer in Embedded Metrology Applications

“…Three-dimensional artefacts for areal calibration have also been developed for the determination of surface characteristics and lateral resolution [8,9]. Alternatively, transparent artefacts for optical micro-CMM [10] and optical coherence tomography (OCT) [11][12][13] are also present in the literature.…”

Femtosecond laser inscribed advanced calibration phantom for optical coherence tomography (OCT)

“…However, those methods do not address to all the requirements to quantitatively calibrate and assess the OCT system and associated image distortion when imaging through a curved surface. Femtosecond laser direct writing technique has been used previously for the purpose of phantom inscription at Aston [5], where a non-planar multi-purpose phantom was developed [6] where the planar side could be used for a standard assessment and calibration while the curved side could be used to test the validity of the post-processing algorithm for the image distortion. However, this phantom was inscribed with grid pattern that requires a higher degree of alignment in terms of the angle of the sample to generate a useful calibration phantom for the OCT operator.…”