Research / 2021 / Article / Fig 4

Research Article

Quantifying Information via Shannon Entropy in Spatially Structured Optical Beams

Figure 4

The schematic of the experimental setup, where a spatially filtered Gauss-like 635 nm, 4 mW (Thorlabs LDM635) laser beam is reflected off the spatial light modulator (SLM) onto the mirror M1, into the boxing of the Shack-Hartmann sensor (SHS) (Thorlabs: WFS20-7AR). The device is optimized to operate with ordinary Gauss-like signals. The SLM can be set to a mirror regime or to generate an orbital angular momentum (OAM) beam of Laguerre-Gauss-like profile. The OAM beam generation is accomplished by an SLM loaded with a computer-generated diffraction pattern with a fork dislocation (i). In that case, the measured intensity distribution of an OAM beam (ii) has a typical doughnut-like structure. L1 and L2 are the lenses of the beam expander; P1, P2, and P3 are the pinholes; M1 and M2 are the directing mirrors; and LT are the boxing elements of the SHS.