Abstract
The use of solid frustrated total internal reflection (FTIR) layers to control the polarization effects in optical coatings usually results in large substrate sizes and complicated designs. To overcome this problem, it is proposed to incorporate an air FTIR layer into the multilayer thin film coatings. The low refractive index of air not only helps to reduce the substrate sizes, but also simplifies coating designs or improves the performance. The principle and layer structures of the proposed multilayers are described. Examples of polarizing- and non-polarizing beam-splitters for the infrared spectral region are given. Some practical manufacturing issues are also discussed.
Highlights
Thin film optical coatings or filters are often used in applications that require light incident at non-normal or oblique angles of incidence in order to physically separate the incident, reflected and transmitted beams from each other
One issue with optical coatings used at oblique angles, especially on prism substrates, is the polarization effect between s- and p-polarized light
In an frustrated total internal reflection (FTIR) optical thin film coating where the incident angles are greater than the critical angle (n0/n1>1 and θ0>θC) within low index FTIR layers, the phase changes on reflection at high/low layer interfaces are not fixed at 0° or 180° anymore but vary with angle of incidence and the polarization state
Summary
Thin film optical coatings or filters are often used in applications that require light incident at non-normal or oblique angles of incidence in order to physically separate the incident, reflected and transmitted beams from each other. It has been demonstrated that the combination of frustrated total internal reflection (FTIR) and thin film interference is very effective in the design of polarizing and non-polarizing thin film beam-splitters operating at angles greater than the critical angle [2,3,4,5,6] These coatings consist of solid thin film layers sandwiched between two high refractive index prisms. In the infrared spectral region ZnS and ZnSe are commonly used as the low index layer material and the substrate material This combination results in a very large critical angle above which the optical coatings must operate.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
