Conventional dental photo­graphy technology has had a limitation in using inconvenient tools such as mirrors and cheek retractors. Dentists require basic teeth images from various angles, such as right/left buccal and maxillary/­mandibular occlusal, for dental health inspection. To acquire these images, patients feel discomfort because dentists must put a mirror into the mouth to capture the reflected teeth image through a handheld camera. Information such as tooth arrange­ment and the location of tooth decay can be obtained through this process. A compact intraoral dental camera can overcome the discomfort and scan the condition of teeth. However, due to the restricted depth of field and field-of-view, the conven­tional device has limi­tations in close-up imaging for observing tooth decay in detail and wide-angle imaging for capturing the entire arrangement of teeth.

Various species of compound insect eyes have superior visual characteristics, such as wide viewing angle and large depth of field with compact visual organs made up of tiny lenses. Insect eyes give inspira­tion for minia­turized cameras, and insect-inspired cameras can solve the problems of conven­tional compact cameras, such as limited observation range. However, previously developed insect cameras have drawbacks in low-resolution or limited functions. Now, researchers from Korea Advanced Institute of Science and Technology and Korea Photonics Technology Institute recently developed a novel wide-angle insect eye camera, the bio­logically inspired intraoral camera (BIOC), for assorted functional imaging. Using the device, assorted functional imaging was demons­trated to satisfy clinical needs.

The BIOC involves a new confi­guration of convex-concave lens and inverted micro­lens arrays (iMLA) and a single CMOS image sensor on a flexible printed circuit board in a handpiece holder. The convex-concave lens sub­stantially increases the field of view up to 143 degrees, and iMLAs reduce optical aberra­tion by the scaling law. In addition, the new camera overcomes many chronic issues of conventional intraoral cameras, such as limited depth-of-field, thick total-track-length, and limited functional imaging. In detail, the ultrathin dental camera can solve discomfort states owing to its thinness and observe teeth even in anatomi­cally narrow regions. Also, clear dental imaging is achieved without image blur by emulating the insect vision feature of infinite depth of field even at close object distance. The BIOC offers multifunctional dental imaging, such as high dynamic range, 3D depth, and auto­fluorescence imaging, through the multichannel vision system.

The scientists hope that the novel wide-angle insect eye camera contri­butes not only technical advances in biomedical engineering societies but that it also has signi­ficant impacts on such diverse vision appli­cations as surveillance, smartphone, and drones. They anticipate a continuing expansion in appli­cations in the future. (Source: SPIE)

Reference: K. Kim et al.: Biologically inspired intraoral camera for multifunctional dental imaging, J. Opt. Microsys. 2, 031202 (2022); DOI: 10.1117/1.JOM.2.3.031202

Link: Biophotonics, Korea Advanced Institute of Science and Technology KAIST, Daejeon, South Korea