Two-color differential dynamic microscopy for capturing fast dynamics

Abstract

Differential dynamic microscopy (DDM) is increasingly used in the fields of soft matter physics and biophysics to extract the dynamics of microscopic objects across a range of wavevectors using optical microscopy. Standard DDM is limited to detecting dynamics no faster than the camera frame rate. We report on an extension to DDM where we sequentially illuminate the sample with spectrallydistinct light and image with a color camera. By pulsing blue and then red light separated by a lag time much smaller than the camera's exposure time we are able to use this two-color DDM method to measure dynamics occurring much faster than the camera frame rate. The following article has been accepted by Review of Scientific Instruments. After it is published, it will be found at https://aip.scitation.org/journal/rsi.

Differential dynamic microscopy for the characterization of polymer systems

“…61 Moreover, the continuous progress in imaging sensors technology and the introduction, in combination with DDM, of clever acquisition/illumination schemes will enable access to unprecedentedly fast dynamics. 62,63 DDM is robust against multiple scattering compared to DLS, and has been exploited by many investigators to study samples that would otherwise have been impossible with optical methods. However, a systematic study of the effects of multiple scattering on DDM analysis is still missing, and understanding the associated limitations could be important for extending DDM to a wider class of samples and experiments.…”

“…The use of DDM as a diagnostic tool for quasi‐real‐time monitoring of samples during production, processing, transport or aging is fostered by the availability of optimized software implementations, enabling the quasi‐real time DDM analysis of an acquired image sequence 61 . Moreover, the continuous progress in imaging sensors technology and the introduction, in combination with DDM, of clever acquisition/illumination schemes will enable access to unprecedentedly fast dynamics 62,63 . DDM is robust against multiple scattering compared to DLS, and has been exploited by many investigators to study samples that would otherwise have been impossible with optical methods.…”

Differential dynamic microscopy for the characterisation of motility in biological systems

“…Two recent developments in DDM allow for the measurement of dynamics faster than the camera frame rate: two-colour DDM, which correlates the signals from rapidly alternating blue and red illuminations to access faster delay times, allowing access to fast dynamics; 46 and Cross-DDM, which cross correlates the images collected by two cameras, again allowing access to faster dynamics. 47…”

“…Two recent developments in DDM allow for the measurement of dynamics faster than the camera frame rate: two-colour DDM, which correlates the signals from rapidly alternating blue and red illuminations to access faster delay times, allowing access to fast dynamics; 46 and Cross-DDM, which cross correlates the images collected by two cameras, again allowing access to faster dynamics. 47 A related technique is Differential Variance Analysis (DVA) which also calculates difference images, but instead of performing a Fourier analysis it looks at the real space variance of fluctuations in the difference images to extract dynamical variables.…”

Differential dynamic microscopy for the characterization of polymer systems

“…The use of DDM as a diagnostic tool for quasi-real-time monitoring of samples during production, processing, transport or aging is fostered by the availability of optimized software implementations, enabling the quasi-real time DDM analysis of an acquired image sequence [62]. Moreover, the continuous progress in imaging sensors technology and the introduction, in combination with DDM, of clever acquisition/illumination schemes will enable access to unprecedentedly fast dynamics [63,64]. DDM is robust against multiple scattering compared to DLS, and has been exploited by many investigators to study samples that would otherwise have been impossible with optical methods.…”