Multi-speckle diffusing wave spectroscopy with a single mode detection scheme

TL;DR

This paper introduces a novel single setup detection scheme for diffusing wave spectroscopy that uses a rotating diffuser to efficiently perform ensemble averaging, achieving high-quality correlation measurements without additional time averaging.

Contribution

The authors develop a two-cell geometry with a rotating diffuser enabling ensemble averaging in DWS without extra time averaging, outperforming camera-based multi-speckle methods.

Findings

Comparable or superior performance to camera-based techniques

Enables measurement of full autocorrelation function over 10 decades

Eliminates need for additional time averaging

Abstract

We present a detection scheme for diffusing wave spectroscopy (DWS) based on a two cell geometry that allows efficient ensemble averaging. This is achieved by putting a fast rotating diffuser in the optical path between laser and sample. We show that the recorded (multi-speckle) correlation echoes provide an ensemble averaged signal that does not require additional time averaging. We find the performance of our experimental scheme comparable or even superior to camera based multi-speckle techniques that rely on direct spatial averaging. Furthermore, combined with traditional two-cell DWS, the full intensity autocorrelation function can be measured with a single experimental setup covering more than 10 decades in correlation time.