Guided optimization of a good starting design can lead to a final design that can be reverse engineered. We apply this to a wide bandpass filter and indicate its deposition with optical monitoring.

Coating Design of a Broad Band Visible Transmitting Filter with Sharp Cut-On and Off Transitions

Glass selection for hyperachromatic triplets (A)

This paper reports on the development of dielectric and amorphous silicon-based thin film stacks for applications at room and liquid nitrogen (LN) cryogenic temperatures. The deposition process was performed using assisted energetic evaporation processes such as Reactive Low Voltage Ion Plating (RLVIP) and Ion Assisted Deposition (IAD). Dielectric coatings produced by RLVIP exhibited fairly good stability at LN temperature. Indeed, as compared to room
temperature, a spectral shift of ∇λ0.5 = -2.9 nm at half maximum was obtained for a 3-cavity bandpass filter centered at 1570 nm. Amorphous silicon and silicon dioxide stacks deposited by IAD processes were tested for optical applications. Amorphous silicon thin films showed good mechanical stability at LN temperature. The influence of deposition parameters and operating temperature on the electrical, mechanical and optical properties of amorphous Si
films was investigated.

Development of dielectric and amorphous-silicon-based thin film coatings for room- and cryogenic temperature applications

As for the optical measurement, the longer the focal length of collimator is, the less the measurement error is. However, the longer the focal length is, the more difficult the optical design is. It’s higher application value to design long focal length collimator with wide-view. The paper designs a collimator with 2000mm focal length, 4 degree field of view and its wavelength range is from 480nm to 750nm. The collimator is employed in the camera resolution detection system. It adopts the apochromatism three-piece-type structure and the secondary spectrum is corrected. The paper analyses the imaging quality of the optical system and the MTF curve is presented.

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Design of the Wide-view Collimator Based on ZEMAX

A fast (F/1.55) and wide-angle refractive camera objective has been developed to work with a large-size CCD on the focal plane of the spectrograph of Mont Megantique telescope for large spectral coverage from UV to VIS and up to NIR. The novel camera objective has been designed and optimized with three different glass combinations in order to have higher throughputs for large spectral coverage, especially in UV region. The tolerance analysis of the camera objective is given in the paper. The final opto-mechanical design of the objective is discussed with the consideration of the manufacturing tolerance in the optical and mechanical parts, as given in this paper. The used components have been minimized to reduce the light inherent lost. The optical testing results displayed the good optical performance of the camera with the required resolution for the whole FOV, as predicted by the optical simulation and computation. The broadband AR coating, enhanced on UV region, have been used on each surface of the lenses in the optical system.

Development of fast camera objective for spectrograph of Mont Megantique telescope

All-reflective optics is conventionally required for extended spectral region observations in astronomical spectrograph But the spatial resolution is usually not good enough while the large-size CCD will be used for observation in all-reflective optics In this paper, all-refractive optics has been investigated to design a fast (F/155) and wide angle camera objective for large spectral coverage, from UV to VIS and up to NIR, when a large-size CCD is used on the focal plane of the spectrograph of Mont Megantique telescope The case of achromatic and apochromatic condition has been investigated for axial and lateral color controls The new proposed solutions have been optimized from two to three different glass combinations in order to have higher throughputs for large spectral coverage, especially in UV region The used components have been minimized to reduce the light inherent lost The monochromatic aberrations have been corrected and controlled by using optimized lens bending and shapes to make the camera have the CCD pixel resolution Ray tracing results displayed the good optical performance of the camera to cover from 350 nm to 1000 nm spectral region with high resolution The broadband AR coating, enhanced on UV region, will be used on each surface of the lenses in the camera Final throughputs for the designed camera has been estimated and given in the paper

Simon Thibault

Papers

Fast camera objective designs for spectrograph of Mont Megantique telescope