| Summary: | 碩士 === 國立中央大學 === 光電科學與工程學系 === 104 === The study is about the design of ultra-wide lens, which has 4 Mega pixel, and compose of seven glass, the focal length of the lens is 2.212 mm, the total length is 22.66 mm, F/# is 2.2, the maximum of half field-of-view is 80 degree. The purpose of the study is to discuss about thermal analysis and correction of the ultra-wide lens when the ambient temperature range from -20C to 60C.
The ambient temperature change not only making the refractive index of optical element change, but also making the radius, thickness of optical element, the space of air, the aspheric coefficient of surface and the mount are change. We must consider the temperature coefficient of the refractive index (dn/dT), the thermal expansion coefficient of the lens (α) and the thermal expansion coefficient of mount (β).
With the ambient temperature change, the optical parameter values of optical element are change. In addition, the optical construction change affects the location of the focus. So we design athermal optical system, we make the change in optical power which due to a temperature change (d/dT) is zero. The d/dT relate to the temperature coefficient (dn/dT) and the thermal expansion coefficient of the lens (α). If d/dT cannot be eliminate, using the thermal expansion coefficient of mount (β) compensate to achieve athermal design. In this study, we choose different mount material to athermalized.
In the ambient temperature range from -20C to 60C, the MTF (180 lp/mm) of the ultra-wide lens are larger than 0.451. The relative illumination can achieve 78.06 %. The maximum of lateral color from short wavelength (F-line) to long wavelength (C-line) is 1.482 m. The maximum of lateral color from short wavelength (F-line) to reference wavelength (d-line) is 0.848 m. The maximum of F-theta distortion is 0.78 %. And the minimum of MTF (180 lp/mm) of tolerance analysis is 0.210.
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