Design and analysis of non-polarizing beam splitter in a glass cube

The reflectance and transmittance of thin films at oblique incident angles exhibit strong polarization effects, particularly for the films inside a glass cube. However, the polarization effects are undesirable in many applications. To solve this problem, non-polarizing beam splitters with unique optical thin films have been achieved employing a method of combination of interference and frustrated total internal reflection, the non-polarizing condition expressions based on frustrated total internal reflection has been derived, and the design examples of non-polarizing beam splitters with an optimization technique have been also presented. The results of Rp=(50±0.5)%, Rs=(50±0.5)% andΔr=(0±0.3) degree in the wavelength range of 400-700nm have been obtained. The thickness sensitivity of NPBSs is also analyzed.