Abstract
An ultra-wide angle lens design with relative illumination analysis is presented. The half field angle of 80°, the relative illumination of the image plane will be reduced. It is necessary to increase the image numerical aperture ratio for X and Y direction, and decrease the angle between the chief ray and optical axis in the image space. However the ultra-wide angle lens induces great barrel distortion causing image extrusion. Therefore, we use F-theta distortion to replace optical distortion. Seven lenses and two pieces of flat glass are used for a sensor 1/6” sensor with 2.1 million pixels. The final result for the lens is a half viewing angle of 80°, F/2.4, a focal length 1.1 mm, a length of 22.37 mm, F-theta distortion of less than 2%, and relative illumination greater than 83%.
Highlights
Optical lenses with half field angle greater than 60◦are called ultra-wide angle lenses
The relative illumination and F-theta distortion must be considered in the ultra-wide angle lens design
Where Eθ is the illumination of the image point from the incidence ray of the half field angle θ in the object space; Eobj is illumination of object; R is the reflectivity of the object; TL is the penetration of the lens; Θ is the chief angle in the image space; N Aθ is the numerical aperture of the image point from the incidence ray of the half field angle θ
Summary
Optical lenses with half field angle greater than 60◦are called ultra-wide angle lenses. In the fisheye lenses half field angle is equal to or exceeds 90◦called. W. Wood [1] used a pinhole in front of a container filled with water as the prototype of the first ultra-wide angle lens, simulating the fisheye image in the water. Many improvements have been made to the ultra-wide angle lens design since that time. The current generation of ultra-wide angle lenses has been used in many places, such as: J. The requirements are as follows; half field angle ranging from 70◦to 90◦, and a number of elements ranging from 7 to 11; the overall length of the lens is from 25 mm to 40 mm, and the f number is 2.8. Design specifications used in this study include an 80◦half field angle, 7 lenses with a length 22.37 mm, and F/2.4
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More From: Journal of the European Optical Society-Rapid Publications
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