Use of focus stacking and SfM techniques in the process of registration of a small object hologram

Paśko, Sławomir; Sutkowski, M.; Bakanas, Ramūnas

doi:10.3788/col202018.060901

Cited by 1 publication

(1 citation statement)

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“…related to the curvature of the lenses. Nevertheless, for future applications of this technique, the application of image processing techniques as well as focus stacking ones, or the introduction of a compensating phase-curved term in the propagation calculations or in the illuminating beams, could lead to an artificially increased depth of field as a combination of different focused planes at different distances of the same sample or a single focus of the whole curved surface [ 51 , 52 , 53 ].…”

Section: Discussionmentioning

confidence: 99%

Soft Contact Lens Engraving Characterization by Wavefront Holoscopy

Vila-Andrés,

Esteve-Taboada,

Micó

2024

Sensors

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Permanent engravings on contact lenses provide information about the manufacturing process and lens positioning when they are placed on the eye. The inspection of their morphological characteristics is important, since they can affect the user’s comfort and deposit adhesion. Therefore, an inverted wavefront holoscope (a lensless microscope based on Gabor’s principle of in-line digital holography) is explored for the characterization of the permanent marks of soft contact lenses. The device, based on an in-line transmission configuration, uses a partially coherent laser source to illuminate the soft contact lens placed in a cuvette filled with a saline solution for lens preservation. Holograms were recorded on a digital sensor and reconstructed by back propagation to the image plane based on the angular spectrum method. In addition, a phase-retrieval algorithm was used to enhance the quality of the recovered images. The instrument was experimentally validated through a calibration process in terms of spatial resolution and thickness estimation, showing values that perfectly agree with those that were theoretically expected. Finally, phase maps of different engravings for three commercial soft contact lenses were successfully reconstructed, validating the inverted wavefront holoscope as a potential instrument for the characterization of the permanent marks of soft contact lenses. To improve the final image quality of reconstructions, the geometry of lenses should be considered to avoid induced aberration effects.

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Section: Discussionmentioning

confidence: 99%