Comparative Study On Collimation Measurement Based On Different Light Sources

In high-precision machining or measuring equipment,collimation measurement is the measurement basis of geometrical parameters and geometric error,such as straightness,verticality,concentricity,etc.However,the collimated beam will be affect by many factors,and drift,then make accuracy of these systems limited severely.How to reduce the influence caused by beam drift and to improve the stability of measurement systems,has been focused on research.In this dissertation,taken a Laser Diode(LD)as the comparison object in collimation measurement,a series of comprehensive research were conducted using a Superluminescent Diode(SLD)and a white Light-Emitting Diode(w-LED)which are two kinds of non-laser light source.Firstly,the principle and property of optical output of three kinds of light source were studied,and characteristics of them were studied and compared.Secondly,comparative study on collimation measurement using SLD and LD,and similar study using w-LED and LD,were conducted successively.The main contents and results of this dissertation are concluded as follows.1)Through stability comparison experiments based on collimated beam using SLD and LD,it was found that the optical output of LD will change when working for a long time due to deformation of the resonant inner the laser,while the output power of SLD could be stable for a long time,In terms of stability of positioning,the beam of SLD performed slightly better than LD.Taking shortcomings of high-cost and large-volume into account,SLD has no obvious advantage when used in collimation measurement,when compared with LD.2)Through stability comparison experiments based on collimated beam using w-LED and LD,it was found that the LD needs to preheat before working,and its intensity was unstable.While the beam from the w-LED could keep unchanged for a long time without preheating.In addition,as a kind of cool source,the w-LED introduced less drift of light beam caused by deformation of mechanical structure resulting from heating by the source.In research on influence of air disturbance,it showed that the w-LED perfects not good as the LD,since the components of different wavelengths are affected to varying degrees.3)Through verification experiment of taking collimated beam from the w-LED as measurement datum,it was showed that intensity distribution of beam of the w-LED kept unchanged in propagation.The w-LED has lower cost,smaller volume,less heat,and more stable power,so that it can be applied for collimation measurement for short distance.