Technical layout and fabrication of a compact all-glass four-channel beam splitter based on a Kösters design

Abstract

We report on the design and fabrication of a novel all-glass four-channel beam splitter based on a Kösters prism for use in space. The Kösters prism, which consists of three pairs of individual prisms, is used to separate an incoming telescope beam into four spectral channels (λ = 800–1700 nm) with the goal to obtain a multi-band photometry of cosmic sources in the optical/near-infrared bands. We performed optical design studies to evaluate the influence of geometrical tolerances of the six individual prisms on the image quality. A stray light analysis revealed the impact of the composition on the overall optical performance. Mechanical design studies benchmarked possible mounting strategies. We considered optical adhesives, soldering and clamping. The influence of the mechanical loads during a rocket launch as well as thermal loads at 140 K (the operation temperature of the optical element) were studied. We optimized the coating properties of the prisms by considering the results from the optical design study as well as the technological requirements for the direct bonding of the prisms. Bonding strategies to realize the prism pairs were developed and successfully tested. A demonstrator Kösters prism was manufactured and is ready to validate its optical performance.

Albedo bias reduction for Nanocarb GHG sensor: comparison of panchromatic or hyperspectral ancillary imager, and high finesse or multiple harmonics Fabry-Perot interferometer

“…The AR coating and the filter coatings are necessary to meet the high requirements on the optical performance of the whole beam splitter setup. 4 A ternary design of the coating system is used to keep the overall coating thickness at 4 µm. SiO 2 serves as low-index material and silicon as high-index material for the beam splitter coating systems.…”

“…Details on the evaluation of their optical properties can be found here. 4 A final SiO 2 layer was included in the coating design, which provides the interface for the bonding.…”

“…In the end, silicate bonding outperformed the other approaches. 4 Silicate bonding (also known as hydroxide catalysis bonding) is widely used for structural assembly in gravitational wave detectors, also in space. 8 applied onto one sample surface.…”

NIR to LWIR Dichroic Beamsplitter Designed and Manufactured for Space Optical Remote Sensor

“…A dichroic coating stack is deposited on one side for the spectral splitting required by the optical system, and the AR coating stack is deposited on the other side for the wavelength range of the transmission area. So far, some researchers have reported [12][13][14] on the development of infrared dichroic beamsplitters and obtained excellent research results. A dichroic beamsplitter was designed by Hendrix et al [15]; band separation occurred on the first optically flat surface, and it separated the SWIR and MWIR bands.…”

“…A study has been carried out on the design and fabrication of the dichroic coating on zinc selenide flat substrate [16]. The dichroic beamsplitter could separate the 3 to 5 µm and 7.5 to 10.5 µm wavelength regions when it So far, some researchers have reported [12][13][14] on the development of infrared dichroic beamsplitters and obtained excellent research results. A dichroic beamsplitter was designed by Hendrix et al [15]; band separation occurred on the first optically flat surface, and it separated the SWIR and MWIR bands.…”