Research On The Technologies Of Electrohydrodynamics For Quantum Dot Encoders

Linear encoder（also known as grating ruler）is a type of optical encoder and the grating on its code pattern is the basis for linear displacement measurement.Optical encoder for displacement measurement have been widely used in many fields such as CNC machine tools,precision measuring instruments and high-precision motion platforms,which are of great significance to my country’s economic development and scientific or technological progress.At present,the gratings on the optical encoder are manufactured by different surface etching techniques,including mechanical scribing,holographic lithography,X-ray and electron beam lithography,and extreme ultraviolet lithography.However,due to the above-mentioned grating etching technology have the defects such as high cost,complex process,low yield and slow forming speed,may not be able to meet the sustainable development requirements of grating manufacturing in the future.With the rapid development of foreign technology for describing gratings and the progress of AI decoding technology in the future,the strict embargo on my country’s high-precision gratings produced by them will pose a huge security threat to our country’s measurement and control industry chain.Therefore,the industry needs to find another way for the manufacturing process and encoding and decoding methods.Exploring the feasibility of the new process to manufacture the code pattern and create an encode and decode method for the displacement measurement.At present,the printing of precise nanoscale patterns can be achieved through the near-field direct-writing technology in the additive manufacturing.In addition,quantum dots,as a new type of nanoscale display material,have their own luminescent properties,which provide a new idea for the construction of code pattern insteading grating.Accordingly,this thesis combines the above two,and proposes a new linear encoder（referred to as quantum dot encoder）that uses quantum dots to print special code patterns based on additive manufacturing.The main research contents are as follows:（1）Complete the design and realization of a device suitable for electro-hydrodynamic processing,which can meet the process requirements of electro-hydrodynamic near-field direct writing and Electrospray printing by changing the printing modules on the Z axis.At the same time,it is equipped with different external signal modules to realize the process technology.Finally,the feasibility of the device is proved by the COMSOL Multiphysics simulation and the real-time monitoring of the high-speed camera.（2）Exploring the optimal process parameters for the fabrication of the code pattern of the quantum dot encoder.First,by comparing with the existing organic materials,a new type of quantum dot printing ink suitable for near-field direct writing process was created.Then,the code pattern was analyzed and designed and the experiment of exploring the optimal process parameters of the dot printing ink was begin.Finally,the luminous performance and dimensional consistency evaluation of the completed code pattern determine the feasibility in the displacement measurement.（3）Construct a set of image acquisition system suitable for quantum dot encoder and propose an algorithm for encoding and decoding displacement value.At the same time,the developed image acquisition system is beneficial to avoid the thermal deformation error caused by the light source to the grating substrate.Finally,two key algorithms for code pattern fitting are proposed,which are used for the comparison of the next displacement value measurement,and the best measurement accuracy of the quantum dot encoder is obtained.（4）Design and develop a interface suitable for displacement measurement of quantum dot encoders,from which real-time motion displacement values can be derived intuitively.Then,the design of the measurement accuracy experimental method and the summary and analysis of the experimental data are carried out.The positioning accuracy of the two key algorithms is obtained,which proves that the design and application of the quantum dot encoder is feasible.Finally,according to the summary of experimental experience,a method that is beneficial to improve the accuracy of quantum dot encoder is proposed and its future development is prospected.