The most important procedure for improving accuracy of modeling in stereo-lithography is to clearly identify the relationship between the conditions of laser irradiation and the solidification of photo-curing resin for modeling. The parametric study concerning laser power, laser beam diameter, laser scan speed and properties of photo-curing resin was conducted in order to find those influence on the dimensional accuracy of the solidified resin.
This paper describes a structured lighting method for the measurement of surface profiles of mat objects. In this kind of profilometry, a grating with binary transmittance distribution has been utilized. In these cases such a problem is known that an error is caused due to the non- sinusoidal transmittance of the grating. Another practical difficulty is in mechanical shifting of the grating. Here we propose to use a hybrid grating which consists of a conventional binary grating and a liquid crystal (LC) binary grating. Moire pattern produced by superposing these two binary gratings is available to overcome these problems. When two binary gratings are overlapped, the resultant moire pattern becomes closely sinusoidal in intensity distribution. And, when the LC grating pattern is moved, the projected pattern can be shifted arbitrarily in phase. Surface profiles of some samples are measured to show validity of hybrid grating projection and utility of the prototype system.
In a stereo-lithography, the most important procedure for improving an accuracy of modeling is to clearly identify the relationship between the method of laser irradiation and the solidification of photo-curing resin. Thus, a theoretical analysis was made in order to find any effect on the solidification, viz. Thickness and width of solidified resin influenced by laser power, laser beam diameters, laser scanning speeds, and properties of photo-curing resin, and these analytical results were compared with respective test results. The results are summarized below: (1) the cured thicknesss of solidified resin can be represented by a function of the energy density at the center of laser, the attenuation coefficient and the critical curing energy density of photo-curing resin. (2) The cured width of solidified resin can be represented by a function of laser beam diameters, the energy density at the center of laser and the critical curing energy density of photo-curing resin. (3) Photo-cured models, which have been manufactured by controlling energy density at the center of laser, would have high manufacturing accuracy, and therefore, can be applied as industrial design models.