Ultrawide-angle optical system design for light-emitting diode-based ophthalmology and dermatology applications

BACKGROUND: Compared to laser, light-emitting diodes - non-coherent and divergent light sources requires that the developed optical system support steering and focusing of light on the desired target when acquiring information regarding human tissues. OBJECTIVE: A new optical system with an ultrawide angle was designed to cover large areas of the eye, including facial areas near the eye, in order to overcome the limited field of view of optical systems used for ophthalmology and dermatology applications. METHODS: To achieve a compact and handheld optical system for ophthalmology and dermatology applications, a contrast auto-focus (AF) method must be used, and the weight reduction of the AF group is considered during the design process to satisfy the effective focal length (EFL), back focal length (BFL), and front focal length (FFL) in the proposed optical system using Gaussian-bracket method. RESULTS: The designed optical system can focus from infinity to a magnification of -0.19 times, representing a distance of 114.359 mm from the first surface of the optical system to the object. The AF lens moving distance from infinity to the minimum distance is approximately 4.984 mm. The full width at half maximum (FWHM) values of the red, green, and blue light-emitting diodes were 16 mm, 35 mm, and 22 mm, respectively. CONCLUSIONS: We have designed an ultrawide-angle optical system for compact optical systems that are suitable for high-performance ophthalmology and dermatology applications.