Figure 8.

Self-referenced transmission matrix measurement. (a) Beam in the plane of the SLM. A fraction of the beam incident on the sample is modulated. Another part of the beam remains static and serves as a reference for interferometric acquisition. (b) The modulated and the static reference beam are both scattered at the sample and interfere at the detector (compare Figure 5). (c) A sinusoidal intensity fluctuation is observed in case the phase of the modulated part of the wavefront is changed. The phase and amplitude of the scattered field which results from sample illumination with the modulated wavefront segment, i.e., one column of the transmission matrix, can be determined from this signal using phase-shifting algorithms. Image from [8], with permission.