Traditional optical metrology techniques face significant challenges when applied to biological specimens, largely due to the specimens' inherent transparency. This often results in inadequate imaging and compromised measurement accuracy. To circumvent these challenges, confocal microscopy has become the preferred method for metrological analysis of such samples. However, it is important to note that confocal microscopy is fundamentally a point -based technique, which inherently limits its field of view (FOV). In this paper, we explore the application of a depth-from-focus method for the 3D mapping of biological tissues in a wide FOV. Although this technique is well-established for reflective and absorbent samples, its use has been limited with transparent, and specifically biological, samples. The lack of critical surface texture in transparent samples hinders the acquisition of the necessary imaging detail when using traditional transillumination or epi-illumination systems. Additionally, conventional high-resolution depth-from-focus systems typically employ microscope objectives that yield a narrow depth of field however limiting the FOV due to high magnification. We address these challenges by introducing two key innovations. First, we implement a ring LED illumination system to enhance the clarity of the sample surface image. Second, we substitute the microscope objective with a photographic lens paired with a larger sensor to expand the FOV. These adaptations, along with a developed focus estimation algorithm, enable high-resolution 3D mapping of biological tissues, overcoming the limitations of existing methods.
A novel multichannel optical imaging system capable of high-resolution imaging across a wide field of view (FOV) of 7x7 mm2 with a 4x magnification. Comprised by microlens arrays (MLAs) and micro-aperture arrays, our design circumvents the traditional trade-off between resolution and field size. Each channel of the system is optically isolated by microaperture arrays acting as field stops, ensuring high-quality imaging without crosstalk. A 5x5 step micro-scanning technique extends the imaging capability to the entire FOV. Experimental validation of the prototype, which employs commercially available MLAs and fabricated micro-aperture arrays, demonstrates agreement with theoretical predictions, achieving clear imaging without the need for a large sensor. This approach promises significant advancements in applications requiring detailed imaging over large areas.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.