Research On The Design Of The Five-speed Zoom Lens Of The Focal Length Instrument

With the continuous development of the optical industry,the zoom optical system has been widely used in the fields of medicine,military,industrial testing and other fields.The focometer,as a traditional optical instrument for measuring focal length,has been equipped with a set of fixed focus measuring lenses.The magnification and the working distance of each measuring lens are fixed.When measuring focal distances of different ranges,the focal length instrument needs to replace different measuring lenses.The measurement process is complicated and inefficient,which has been unable to meet the needs of current enterprises.This paper designed a five gears zoom lens to instead of the set of fixed focus measuring lenses.When measuring lenses in different range of focal length,five gears zoom lens can automatic transmission,automatic focusing.In this way,focal length measurement process is more efficient and more automated.It is in line with the trend of measuring the focal length of the future.According to the working principle of the magnification method focometer,this paper computered number of gears,specific parameters and other related indicators of every gear.According to the optical structure design method of optical zoom system,this paper designed a five gears zoom lens.This paper designed optical structure,automatic shift function module,the five zoom autofocus function module and CCD image plane image processing algorithm module.When the theoretical design is completed,the next work is tolerance analysis of the five gears zoom lens,mechanical design,and the specific choice of various auxiliary tools.This paper has also assembled the five gears zoom lens,and testing the performance of the important parameters of five gears zoom lens.The result of test showed that,each gear's magnification were 7.93 times,2.54 times,0.93 times,0.49 times,0.16 times and each gear's working distance were 22.5mm,58.6mm,155mm,301.5mm and 1000mm.Measurement range of five gears zoom lens is(-1000mm,-5mm)U(5mm,1000mm).The image quality of five gears have reached the requirements,through the analysis of the measurement results.It can be concluded that the five gears zoom lens meets the design requirements.