Design and manufacture of off-axis optical reflective integrator with faceted structure

Here, an off-axis optical reflective integrator is designed to transform a parallel Gaussian beam into a uniform intensity beam with a rectangular cross section, which is used in solar simulation systems. The integrator is designed using the faceted structure based on geometrical optics and nonimaging optics, and fabricated by ultra-precision turning to achieve a high efficiency and precision. The advancement in this study is to reduce the stepwise discontinuity among the facets to make it applicable for turning. To improve existing refractive integrators that are large in size and complex in structure, the off-axis optical reflective integrator only needs a mirror that is simple and easy to use. Comparing with an existing reflective integrator whose substrate is a spherical surface, the integrator designed here by the edge ray tracing method is aimed to achieve a smooth connection with flat or conic facets, to reduce the image distortion caused by the large tilt angles, and the discontinuity among the facets. Both the simulations and experiments show that above 90% of illumination uniformity can be achieved using this new design.