Plan apo sl 20x 0

To minimize the acquisition time, we first precalculate the patterns that will be displayed by the DMD. These patterns are split into packets of 79 realizations of input speckles, each containing 21 × 21 patterns which are translated versions of the same speckle. These files are then stored on a solid-state drive (SSD) in a binary format. During an acquisition, each file is loaded on the random access memory (RAM) of the computer (loading time, 2.4 s), transferred into the internal memory of the DMD (transfer time, 8.7 s), and finally displayed by the DMD running at a rate of 2 kHz (display time, 17.4 s). Thus, overall, measuring data for 40,000 realizations takes approximately 4 h. Note that while our DMD could be operated at a rate of up to 23 kHz, working at 2 kHz allows us to improve the signal-to-noise ratio by applying a low-pass filter (−6 dB cutoff frequency: 10 kHz) to the measured signal. Finally, to obtain direct images of the sample, we used a ×20 objective (Mitutoyo Plan Apo SL 20X/0.28) located on the other side of the sample, along with a 200-mm lens, a fluorescence filter (Chroma ET590/50m), and a complementary metal oxide semiconductor (CMOS) camera (Basler acA1300-200um). Direct images were then obtained by averaging the measured images over random illumination patterns coming from the fiber.

Fluorescent objects are composed of latex microspheres (ThermoFisher Scientific, red FluoSpheres, diameter 1.0 µm) dispersed on a glass coverslip. A solution of Poly-L-lysine (Sigma-Aldrich, 0.1 % in H₂O) is first deposited on a clean coverslip in order to fix the microspheres. A solution of fluorescent beads diluted in water is then deposited on the coverslip. Using this procedure, fluorescent beads are randomly dispersed on the sample. In order to detect only the fluorescence of the few beads of interest, we selectively photobleach all other beads within the field of view of the fiber (area of 100 µm × 100 µm) by successively focusing coherent light from a continuous-wave laser (Cobolt 08-DPL, 532 nm, 10 mW after attenuation by a neutral density filter) on the beads using a ×20 objective (Mitutoyo Plan Apo SL 20X/0.28).