Magnetic Fluid Lens Assembly for Variable Focus Terahertz Tomography

The patent applies the dynamics principle by using a magnetic fluid lens where the focal length can be dynamically adjusted by changing the applied voltage. The magnetic fluid's refractive index and distribution are controlled by electromagnetic fields generated by coil structures, allowing continuous variation of focal length from infinity to a minimum value, transforming a static lens into a dynamic adjustable optical element.

The patent implements parameter changes by varying the voltage applied to the electromagnetic generating units, which changes the magnetic field strength and consequently alters the magnetic fluid's distribution and effective refractive index. This enables continuous adjustment of the focal length parameter without changing the physical lens structure, achieving variable focus through electrical parameter control.

The patent applies the pneumatics and hydraulics principle by using magnetic fluid (a liquid) as the optical medium instead of solid lens materials. The magnetic fluid is contained in a sealed cavity and its properties are controlled through electromagnetic fields, similar to how hydraulic systems use fluid pressure control. This allows the lens to achieve variable focus by controlling the magnetic fluid's magnetic properties rather than mechanically moving or deforming solid materials.

The patent employs composite materials by combining magnetic fluid with specific magnetic particle compositions (such as cobalt, nickel, or iron oxide particles suspended in carrier liquid) to create a material with tunable optical and magnetic properties. This composite magnetic fluid allows simultaneous control of magnetic response and optical refractive index, enabling variable focus functionality while maintaining manufacturability through material science approaches.