Research On Image Distortion Correction Technology Of Bottom-up Projection Based Mask Projection Stereolithography

In recent years, the products are becoming more competitive and the demand for shorter development cycles is growing. The rapid prototyping (RP) as one kind of high and new technology has been get rapid development. Compared with other RP technology, bottom-up projection based Mask Projection Stereolithography (bottom-up projection based MP-SLA) has advantages on forming speed and accuracy, so it has broad market prospects and development.The technology is currently caused a research upsurge in the domestic, more and more people begin to study this technology. But on the whole, compared with foreign mature technology and products, we are still in the development stage. Especially with the urgent needs of the medical industry, the high demand on accuracy is increasingly. Therefore, it has an important market value to do the research on distortion. This paper is mainly aim to improve precision and reduce distortion. The main contents of this paper are as follows:This paper discusses the characteristics of bottom-up projection and up-bottom projection based MP-SLA. In this process, the causes of reduced precision and the forming reasons of distortion are analyzed,which mainly due to three aspects, including the aspects of mechanical structure,the energy distribution of the illumination and imaging.For distortion problem, the aspects of correction software have been done. In the software calibration process, the camera calibration, the projector calibration and with the intersection algorithm to achieve the image of the mask production model which with non-uniform distribution of pixel locations has been done.All this can correct the distortion.According to the distribution of energy on the precision, The irradiance distribution was obtained by measuring the irradiation intensity in various regions of the projection plane with a lumeter, and the approximate linear model based on the relationship between the illumination and Image’s Gray-scale is been obtained. To solve the problem of the uneven distribution of irradiance, the different algorithm according different regions are used to homogenize the irradiance distribution. This method in a certain extent solved the problem of the uneven distribution of irradiance.Projector light path of the illumination and imaging systems is one of the main factors causing distortion, this article analyzes the effects from the principle of the optical path of the illumination and projection imaging, and based on the actual situation of the actual equipment, the simulation and optimization are been studied.In this paper, image distortion correction technology of bottom-up projection based mask projection stereolithography has been researched. The sources of distortion have been analysed. Three aspects were studied to reduce the distortion, these have some theoretical significance and practical value of the process.