Design Of Random Microlens Array With Large Scattering Angle

In recent years,optoelectronic devices have been developing in the direction of miniaturization and integration.As micro-optical components,microlens array have received widespread attention.With the advantages of small cell element size,high integration,and flexible design,microlens arrays are playing an increasingly important role in laser lighting,digital projection,laser displays.But there are many problems in application: Firstly,the sublenses in the traditional microlens array are all periodically arranged.The monochromatic and strongly coherent nature of the laser will lead to interference fringes in the homogenized spot when shaping the laser source,which will seriously affect the actual homogenization effect.Therefore,it is necessary to break the relevant periodic parameters and build a random microlens array;Secondly,transmissive microlens arrays can only scatter at small angles and suffer from low face shape transmission for large angle scattering.This paper presents an indepth study of the various shortcomings of conventional microlens arrays for laser shaping applications and proposes solutions:(1)In this paper,a study is carried out for the random approach of microlens arrays.Firstly,a feasible random method is explored by analyzing the interference principle of the microlens array.Then,an optimal design is given for the bottom graph randomization method,which proposes a randomization method that restricts the edge length ratio.Finally,an optimization function is constructed to solve the problem of excessive variation in the aperture of the subunit during the random process.In this chapter,a random distribution method was proposed for random microlens arrays with simple design and generalizability.(2)In this paper,three random microlens array of spherical,free-form surface and transmission-total reflection types are constructed and analyzed.Firstly,the homogenisation effect of spherical lenses at different divergent angles is explored and the feasibility of processing spherical microlens arrays by chemical etching methods is analyzed.A flat-concave spherical random microlens array with divergent dangle of ±5° is constructed.Furthermore,the beam shaping effect is analyzed,and solutions are given for the technical difficulties in processing the spherical arrays by chemical etching methods;Then,free-form random microlens with larger divergent angle and better homogenization effect is designed.The model construction principle of the free-form random array under the photolithography method is given.The free-form random microlens array with divergent angle of ±20° off-axis is constructed.Moreover,the technical difficulties of fabricating free-form random arrays by photolithography are analyzed and solved.Finally,the energy loss of the transmissive surface type is analyzed for different target scattering angles.The combined transmission-total reflection design is proposed to extend the sub-cell scattering angle.A free-form random microlens array with divergent angle of ±41° is constructed.And the contradictory relationship between interference destruction and energy efficiency is balanced by adjusting the randomness.In this chapter,we provide the relevant theoretical basis for the design of random microlens array with large divergent angles.