We at CSTM recently customized a collimator lens, the performance of which could not be achieved using off-the-shelf components. This collimator included three optical elements and one aspherical surface. The fiber outlet is located at the narrow side, and the collimated beam comes out at the wide side. The design addressed a requirement for a limited volume, and resulted in a solution where the distance from the fiber source to the exit surface of the collimated beam, is about 30% of the focal length. In addition, the optics and mechano-optics were designed so that the collimation level would remain stable at a temperature range of 55oC. The realization of the central element was relatively difficult, since its two surfaces are close to being concentric (usually not acceptable). In order to improve centricity, we chose positioning the elements with reference to one another. This measure required in turn non-standard opto-mechanics.
