The vehicle zoom ultra wide angle lens design by using liquid lens technology

Abstract

As camera technology develops, products have improved and people have an increasing demand for visual quality. To increase the field of view, many zooming modules have been designed, which has raised the cost of optic components, increased the amount of calculation required, and complicated image processing technology. To date, dashcam lenses are primarily a compensatory design that cannot autozoom. Developing technology with various focuses for use on different roads has become a critical topic for autopilot development. Possibilities include using a short focus on general roads and using a long focus for freeways. Dashcam lens design requires the ability to cover wide angles. The concept behind wide-angle zooming lenses is that when the focal length is the shortest, the widest monitoring range is achieved. To observe a point at a far distance, we can use optical zoom to increase the focal length, thereby enabling a view into the distance. At this time, the angular field of view is sacrificed. However, a reduction of the angular field of view leads to a reduction of distortion, which subsequently reduces the complexity of back-end image processing and leads to clearer images. The design in this study references the wide-angle lens patent US.20090080093 (Ning in Compact fisheye objective lens, U.S., Patent No. 20090080093, 2011) of Alex Ning, whose optical system consists of six spherical lenses. The angular field of view reached 170°. The total system length is 18 mm, and F/# is 3. The system focus is 1.652 mm. Four groups of liquid lenses were placed in this wide-angle lens. Altering the curvature and thickness of the liquid lenses changes the course of light and forms a new angular field of view. This system consists of three zoom settings, with fields of view being 170°, 160°, and 150°, respectively. The F/# was 2.4. The modulation transfer function at a spatial frequency of 1801 p/mm reached 6%, 0%, and 27%, respectively. F-Theta was controlled within ± 10%. The spot size was smaller than 4 μm, and the field curvature was smaller than ± 0.02 mm. The liquid lenses were successfully introduced into the wide-angle lens to achieve optical zoom without using a conventional mobile mechanical structure.