Foveated endoscopic lens

Abstract

Abstract. We present a foveated miniature endoscopic lens implemented by amplifying the optical distortion of the lens. The resulting system provides a high-resolution region in the central field of view and low resolution in the outer fields, such that a standard imaging fiber bundle can provide both the high resolution needed to determine tissue health and the wide field of view needed to determine the location within the inspected organ. Our proof of concept device achieves 7 ∼ 8 μm resolution in the fovea and an overall field of view of 4.6 mm. Example images and videos show the foveated lens' capabilities.

Confocal foveated endomicroscope for the detection of esophageal carcinoma

“…In a prior publication, Hagen et al were able to demonstrate the initial concept of a foveated endomicroscope [10]. The objective that was fabricated utilizing a combination of custom built aspheric lenses and an off the shelf glass lens produced foveated images with resolution of 7-8 μm on axis and an overall FOV of 4.6 mm.…”

“…Several attempts have been made to produce an imaging system that balances achievable resolution with large FOV by emulating the human eye [10][11][12][13][14][15][16]. Through the human eye, we observe a drop off in imaging performance from the center of the FOV to the edge as most of the spatial detail is sampled in the center due to a higher concentration of rods and cones in the fovea centralis.…”

“…The resulting image contains distinct regions, with a lower resolution area providing "red-flag" surveillance to direct the high-resolution region towards the area of interest in order to inspect with greater detail. Attempted techniques for replicating the foveated phenomenon have included the use of mirrors, spatially tunable phase elements, sensor array manipulation, and high distortion inducing optics [10][11][12][13][14]. Most of these devices however, have been limited by bulky components, further limiting the adoption by clinicians.…”

“…To meet these design requirements, a new foveated endomicroscope was designed in the optical design software ZEMAX (Radiant Zemax, LLC., Redmond, Washington). The objective is loosely based off of a design from our previously published work [10]. Specific changes included removing the off the shelf glass lens and switching to three custom lenses.…”

“…In order to effectively utilize the image produced by the foveated objective, it is necessary to remove the distortion. In our previous publication [10], we were able to remove the distortion and unwarp the image using a piecewise polynomial-mapping algorithm written in Python. We have rewritten the algorithm in MATLAB and to provide a more rapid piecewise polynomial-mapping.…”