With the recent development of less costly uncooled detector technology, expensive optics are among the remaining significant cost drivers. As a potential solution to this problem, the fabrication of IR lenses using chalcogenide glass has been studied in recent years. We report on the fabrication of a molded chalcogenide-glass lens for car night vision and on the evaluation of the lens. The moldability of chalcogenide glass was characterized through transcription properties of the mold's surface. In addition, both IR transmittance and x-ray diffraction patterns of the molded chalcogenide-glass lens were evaluated to verify the compositional and structural stability of the glass material under the given molding conditions.

We examine the effect of temperature on the molding of chalcogenide glass for infrared (IR) lens fabrication and evaluate a molded chalcogenide glass lens. Both the adhesion of the chalcogenide glass to the mold's surface and lens breakage depended on the initial heating temperature and on the molding temperatures in the glass molding process. In addition, the molded chalcogenide glass lens was evaluated based on transcription characteristics of the mold's surface, IR transmittance, and x-ray diffraction patterns. From the analysis results, we verified that the chalcogenide glass lens for IR imaging application could be fabricated by well-controlled temperature conditions.

This study investigated the following two issues using the design of experiment (DOE): (1) grinding conditions of tungsten carbide (WC) mold to fabricate aspheric glass lenses for the megapixel camera phone module and (2) pressing conditions in the molding process using the mold fabricated under the optimum conditions found by DOE. The optimization of the grinding and the pressing conditions with respect to the surface roughness (Ra) of the ground WC and the form accuracy (PV) of the molded lens, respectively, were ascertained by employing factorial design method. As a result of the analysis of variance (ANOVA) and P-value (significance level), it was verified that the depth of cut in the grinding process and, in case of the pressing, the time of pressing step 2 represent the most significant operative variables that affect the corresponding response variable. The WC mold was fabricated under the optimum condition found by DOE and it shows a PV of 0.181 um in aspheric surface. In the optimum condition, percentage transcription ratio is supposed to be 82%.

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