Novel optical spatial filtering methods based on two-dimensional photodetector arrays

Abstract

In this paper, modified opto-electronic non-contact measuring techniques for the determination of velocity, direction of motion and particle size are presented. These techniques are based on the use of two-dimensional structured photodetector arrays such as CMOS sensors. The principle of measurement utilized is the optical spatial filtering method, which is in widespread use in industrial velocimeters.

Speckle-based three-dimensional velocity measurement using spatial filtering velocimetry

“…The in-plane motion is addressed experimentally by a CMOS camera where the spatial filtering is implemented in the postprocessing. Previously, such methods have been demonstrated [10,12] and more recently described in a similar application [13]. The measurement of the out-of-plane motion is facilitated by an integrated optical spatial filter due to its high sensitivity [14].…”

Optics and Spectroscopy for Fluid Characterization

“…This approach was later extended by employing the evaluation of quadrature signals [105]. In 2004, Bergeler and Krambeer proposed to use the orthogonal grating structure of the pixel matrix of a CMOS camera and to evaluate subsections of the image time series that enables 2d2c flow measurements [106]. A detailed system theoretic description of this SFV measurement technique is contained in [107].…”

Optical high-resolution analysis of rotational movement: testing circular spatial filter velocimetry (CSFV) with rotating biological cells

“…1C-0D SFV also allows for the analysis of the movement of two dimensional (Cartesian) images with intensity distributions of ( ) i x y t , , (Bergeler and Krambeer 2004). In 1C-0D SFV, the intensity distributions in y-direction are nullified by the applied grating function.…”

“…zero dimensional) with a high temporal resolution (Michel et al 1998). Recently, the technique has been extended to two (2C; Bergeler and Krambeer 2004), and three-velocity components (3C; Iversen et al 2011), all of which are detected for a fixed position. Like other 0D techniques, such as laser Doppler methods (Albrecht et al 2003), SFV also has the potential for the multidimensional (3C-3D) detection of velocity fields and the movement of complex structures.…”