Improving lateral resolution and image quality of optical coherence tomography by the multi-frame superresolution technique for 3D tissue imaging

Abstract

The multi-frame superresolution technique is introduced to significantly improve the lateral resolution and image quality of spectral domain optical coherence tomography (SD-OCT). Using several sets of low resolution C-scan 3D images with lateral sub-spot-spacing shifts on different sets, the multi-frame superresolution processing of these sets at each depth layer reconstructs a higher resolution and quality lateral image. Layer by layer processing yields an overall high lateral resolution and quality 3D image. In theory, the superresolution processing including deconvolution can solve the diffraction limit, lateral scan density and background noise problems together. In experiment, the improved lateral resolution by ~3 times reaching 7.81 µm and 2.19 µm using sample arm optics of 0.015 and 0.05 numerical aperture respectively as well as doubling the image quality has been confirmed by imaging a known resolution test target. Improved lateral resolution on skin C-scan images has been demonstrated. For 3D SD-OCT imaging of human skin, fingerprint and retina layer, we used the multi-modal volume registration method to effectively estimate the lateral image shifts among different C-scans due to random minor unintended live body motion. Further processing of these images generated high lateral resolution 3D images as well as high quality B-scan images of these tissues.

Multi-Frame Superresolution Optical Coherence Tomography for High Lateral Resolution 3D Imaging

“…To our observation, the deconvolution methods are sensitive to the noise level. If background noise is as low as Figure 10(K), the deconvolution processing will not introduce obvious artifacts (not shown here, referring to our previous work [11]). However, the method in Figure 10(K) is harmful to the spatial resolution.…”

“…After collecting the x-, y-, z-position shifts information which produces best overlapping quality, the multi-frame superresolution processing is then performed layer-by-layer to improve the lateral resolution and reconstruct a high quality 3D image. The details of the estimation performance and overlap quality are given in our published work [11].…”

“…It offers deeper penetration depth [3] and larger scan area [4] than confocal microscope imaging [5] as well as higher resolution [3] than ultrasonic imaging [6]. It is thus widely utilized in 3D imaging of eyes [7,8], skins [9][10][11][12], blood vessels [13], cartilages [14], and numerous biomedical applications.…”

Optical Coherence Tomography for Non-Contact Evaluation of Fastener Flushness

“…The selection of this light source is due to its availability inhouse. For fastener flushness evaluation, it would be desirable in principle to select shorter SLD center wavelength yet with reasonable wide spectral bandwidth to attain a better axial resolution [17]. However, the choice of SLD (e.g., InPhenix) is quite limited.…”

“…The lateral resolution is currently set by the focused beam spot size to be 19 μm, which is enough for fastener flushness evaluation. The lateral resolution may be improved by using shorter focal length lens on the scanner with the trade-off of a smaller FOV or by using a super-resolution technique with the trade-off of a longer scanning and image processing time [17].…”