Research On Laser Precision Preparation Technology Of Hard Brittle Material Optical Devices

In recent years,the requirement of miniaturization,integration of devices becoming much higher with the development of science and technology,especially in the aspect of electronic components.Microminiature devices are widely applied to the fields of photoelectric device,micro-optics,microelectronics,mems,biological sensors.At present,the femtosecond laser used to process micro-optics devices has attracted the attention of many experts and scholars,because it mainly due to the femtosecond laser machining technology compared with traditional laser processing technology in micro-optics device,high precision,processing three-dimensional structures.In this paper,using femtosecond laser combined with different etching methods,we processed micro lens arrays and sapphire window materials at the micron size.It is well known that femtosecond laser often shows the shortcomings of low machining efficiency and surface roughness when machine hard materials.In this paper,the processing method of using ion beam etching combined with femtosecond laser comed up to realize the 3D processing.In the experiments,we use femtosecond laser of the wavelength of 800 nm and the frequency of 500 Hz to process quartz materials,and etched by ion beam etching technology,so we gain the 7x7 and honeycomb micro lens array which have intact shape and good surface roughness.The measurement shows that the micro concave lens have the depth of 1.35?m,and 20?m in diameter.By the test of imaging and,we can see the well effect of focusing and the clear images.At the same time,the results has been shown in hard materials,such as silicon carbide and diamond machining.Then,in the fields of military affairs,industria,aerospace,materials transmittance has been asked for more demands.In this paper,by using the machining methods of combination of wet etching and femtosecond laser to prepare sapphire optical window material.In the experiment,a layer membrane of quartz coated on the surface of sapphire material in order to protect the surface of sapphire material against the damage while femtosecond laser processing inside of sapphire.After scrubed with acetone solution,the Sapphire material put in ethanol solution for 30 minutes by ultraphonic method,and then put it in the distilled water 30 minutes.Then the specimen etched for 6 minutes by using the liquid which mixtures sulfuric acid and phosphoric acid at the condition of 230?,finally the sapphire window materials gained.The experiment shows that the thickness of specimen is 432?m(including 2?m in thickness of quartz film),and it made the size of 1.5 mm x 1.5 mm.And by reactive ion beam etching method,reducing the surface roughness,then get the intact structure of sapphire.After the infrared transmission test,the experiment measure that with double minus reflection array structure of the sapphire substrate in infrared region transmission can be 98%,and with single minus reflection array structure of infrared transmission of sapphire substrate by 92%.In conclusion,by means of the method of combining femtosecond laser and etching technology,we implement process the three-dimensional structure in a hard material,at the same time improves the machining efficiency,and also preliminarily solves the the problem of femtosecond laser machining that poor surface roughness.Second,femtosecond laser combined with wet etching preparation of subwavelength minus reflection structure on technical innovation,can overcome the traditional coating-the thermal and mechanical stress caused by the mismatch problem and shed film damage,at the same time preparation technology is simple,low cost,no mask,free to design the preparation of subwavelength structure parameters.We implement the preparation of optical devices in micron size,meanwhile we provide a new method and thought for the field of micro-optics processing.