Design Of Plasma Lens For Navigation Applications In Low-light

Polarized light navigation is self-contained navigation.The error does not accumulate with time and has strong ability to resist electromagnetic interference.Polarized light navigation can be used to make up the disadvantages of various navigation technologies widely used.It can improve the overall performance of navigation system by combining with the existing navigation technology,so as to adapt to more complex and more diverse navigation requirements.Under this background,the principle and application of polarized light navigation have been widely studied.The existing polarized light navigation method can provide accurate and stable navigation information for the carrier,however,its application scene is still limited to a clear daylight and other non-low-light environment.The solution of the problem that the existing relatively mature polarized light navigation system cannot be used in the light environment to realize the all-weather application of polarized light navigation determines the future of this new navigation technology to a great extent.In this paper,based on the polarized light navigation system verified by experiment,we design a focus device compatible with the sensor polarization sensitive function for the key device in navigation system-the polarized light navigation sensor,so as to realize the future application of the navigation system in the low-light environment.First,this paper systematically introduces the development process of the focused optical devices,and points out that the first generation of traditional optical devices and the second generation of two element optical devices cannot meet the requirements of the application of the navigation sensors in low-light environment.It is proved that the designed corresponding microlens array for the polarized light navigation sensor based on the principle of two element optical devices is unable to meet the requirements by experiments.At the same time,this paper analyses the feasibility and advantages of the third generation planar nanoscale metal lens to expand the polarized light sensor in low-light environment,and systematically introduces and analyses its principle and various parameters.Secondly,according to the phase regulation principle of the planar nanoscale metal lens,combined with the core component of polarized light sensor—sub wavelength nanoscale metal grating,we design a subwavelength nanoscale grating polarizing concentrator which is compatible with sensors and systematically design key parameters of the structure: the width of the slit and the height of the metal layer.We use the Finite-Difference Time-Domain(FDTD)method to simulate the light field distribution.The geometric parameters of the structure are optimized,and the influence of each parameter on the focus position and focusing effect is given.At the same time,the transmittance of TM light is solved by simulation.Finally,a series of structural numerical simulation results are systematically analyzed.The focus of the optimal structure is located in the light outlet 2798 nm of the polarizing concentrator.The light intensity is increased to 16 times,and the transmittance of the polarizer is about 63% in the 450 nm which is the polarized light navigator's sensitive band.The new nanoscale grating polarizing concentrator proposed in this paper realizes light's focusing in low-light environment,which is compatible with the polarization sensitive function of the original relatively mature navigation sensor.It provides an effective reference for the design of nanostructured devices in the future integrated optical path.