Study On Liquid Lens Technology And Its Application In Micro Zoom Optical System

With the development of the modern optical instrument, the optical zoom system has been adopted more widely. But the conventional zoom system is always limited by its designing method and complicated structure in application to micro system. And it also has the disadvantages of easy to be abrased and short using life. Liquid lens is a kind of novel optical device, which can realize active zooming without any moving elements. The liquid lens can provide many new functions which the normal lens can not realize. By utilizing this device, zoom camera can be designed more miniature and smart than before and avoid the objections of complicated structure and short using life.The liquid lens technology and its application in the micro zoom system were discussed in this dissertation. The discussion focuses on two kinds of liquid lens, which include the liquid-filled membrane lens and the electrowetting effect based liquid lens. The main work completed includes:Firstly, the imaging principle and the aberration of the two kinds of liquid lens were analyzed based on the geometrical optical theory and the aberration theory. The aberrations of the liquid lens were studied, when the focal power shifted. A kind of hybrid diffractive-refractive liquid lens was presented to solve the problem that there was no designing freedom can be used to adjust the aberration, when the lens's focal power needed was confirmed. The hybrid diffractive-refractive liquid lens can offer a freedom to adjust the aberration of the system but without increasing its volume and weight, and depressing the stability of its structure. And the imaging principle of the hybrid liquid lens was analyzed based on the diffractive theory, which showed that the Modulation Transfer Function (MTF) of the liquid lens can be increased when the diffractive surface was added. Secondly, two kinds of liquid lens had been fabricated in laboratory and tested. The influence of the material, gravity, liquid density and environmental temperature on the imaging quality was analyzed. The shape deformation of the liquid-filled membrane lens caused by the gravity was calculated by the Finite Element Analysis method. And the impact on the deformation of the lens's aperture, the surface curvature and the density of the filled liquid was studied. The focal power change was analyzed, which was caused by the inconsistence of the density of the two kinds of liquid in electrowetting based liquid lens. And the approach of how to compensate the focal power shift caused by the temperature altering was proposed.Finally, the application of the liquid lens to micro zoom optical system was researched. A method of designing zoom optical system without any moving lens was demonstrated, by using the liquid lens and the hybrid diffractive-refractive liquid lens as core elements, which can avoid the disadvantages of complicated structure and easy to be abrased in the conventional zoom system. And three kinds of micro optical instrument including auto-focusing endoscope system, bifocal zoom endoscope system, and zooming mobile phone lens were designed, which not only realized the function of auto-focusing or zooming in the system, but also satisfied the requirements of the structure and application.