Speed-up chromatic sensors by optimized optical filters

Abstract

The probably best known chromatic sensor is the chromatic confocal point sensor, which is an optical displacement sensor (depicted in Fig. 1). It uses different wavelengths to encode the distance and has one measurement spot. Beside this prominent example, there are plenty of other realizations. E.g. Lee lists fiber optical sensors which measure temperature, displacement, current, strain and more. A variant of the chromatic confocal point sensor is used within this paper as example to apply the proposed method, referred to as CCT (chromatic confocal triangulation) sensor. In contrast to the point sensor the CCT sensor has many measurement spots next to each other (typically 2000 measurement spots in a row)

Impact of Thin Film Fabrication to the Optimization Process of a Multispectral Chromatic Camera

“…The developed filter optimization approach, which is described in [4] in detail, offers a powerful alternative to optimize fabrication tolerant thin film designs. Simulations of the manufacturing process showed, that the uniqueness merit function of a multispectral camera with six filters is very sensitive to layer thickness variations.…”

“…This section roughly explains the novel optimization method, details are covered in [4]. The task is to define a set of filters for a multispectral camera.…”

“…The optical setup ensures that each wavelength corresponds to a unique surface height. A optimization method was developed [4] to optimize filters of a multispectral chromatic camera. The keyword chromatic emphasizes, that the purpose of this multispectral camera is to estimate the wavelength of monochromatic light.…”

“…This additional source of noise is taken into account during optimization and leads to fabrication tolerant layer designs. The sensor principle and the optimization methods are covered in detail in [1], [3], and [4].…”

Multiplex acquisition approach for high speed 3D measurements with a chromatic confocal microscope

“…The optimization of these interference filters for a CCM is described in reference. 6 The purpose of this paper is a technical realization of a multispectral camera, which is especially well suited for high speed measurements. The spectral filtering is performed on the illumination side with six different spectral light sources.…”