Dlp7000

The experimental setup is illustrated in Fig. 2. The light source was a collimated diode-pumped solid-state laser module (532 nm, 4.5 mW, CPS532, Thorlabs, New Jersey, USA). After beam expansion through two achromatic lenses (AC254-030-A-ML; AC254-075-A-ML, Thorlabs, New Jersey, USA), the laser light was spatially modulated using a DMD (DLP7000, Texas Instruments, Texas, USA) and then projected onto the proximal facet of a MMF (105 μm, 0.22 NA, 1 m, M43L01, Thorlabs, New Jersey, USA) via a tube lens (AC254-050-A-ML, Thorlabs, New Jersey, USA) and an objective (20×, 0.4 NA, RMS20X, Thorlabs, New Jersey, USA). The light illuminated area on the DMD included 32 × 32 independent input modes, with each 2 × 2 micromirrors grouped as one mode. An objective (20×, 0.4 NA, RMS20X, Thorlabs, New Jersey, USA) and a tube lens (AC254-0100-A-ML, Thorlabs, New Jersey, USA) were used to magnify the output light beam before it was captured by a complementary metal-oxide-semiconductor (CMOS) camera (C11440-22CU01, Hamamatsu Photonics, Shizuoka, Japan) with a frame rate of 200 frames per second (fps) for MMF characterisation.

To digitally create a complex wavefront, we built a fast 3D focus scanning module based on a super-pixel encoded DMD (fig. S5). The recording beam was expanded by a 20× beam expander to match the modulation area of the DMD (DLP7000, Texas Instruments). The target field, E(x, y), was converted into a binary pattern to be loaded onto the DMD via a super-pixel encoding look-up table. Once the binary pattern was displayed, the target field was modulated on the focal plane of the 4f system by filtering out the first-order diffracted light through a pinhole. By switching to different binary patterns in order, the holograms could be stored in the photopolymer at a refresh rate of 22.7 kHz.
The 3D focus scanning module controlled the focus 3D position by changing the tilt and defocus coefficient of the light field in front of the focusing lens. The target field, E(x, y), can be expressed by $$E(x,y)=A\exp \left\{\frac{2\mathrm{\pi }i}{\mathrm{\lambda }}[\frac{i}{2(l+f)f}(x^2+y^2)+\frac{ax+by}{l+f}]\right\}$$ where f, A, and λ represent the lens focal length, field amplitude, and wavelength, respectively. Further, a, b, and l represent the 3D position of the focal spot. The coordinate origin is the lens focal point. By changing the value of (a, b, and l), the tilt and defocus coefficient of the light field can be changed accordingly, thus focusing the spot at any 3D position.

A schematic diagram of the imaging system is shown in Fig. 1. A pulsed laser (532 nm, 2 ns, 50 kHz, SPOT-10-200-532, Elforlight, Daventry, United Kingdom) was used as the light source for both PA and fluorescence imaging. A DMD with 768 × 1080 pixels (DLP7000, Texas Instruments, Texas, USA) was used to project binary patterns onto the proximal end of a MMF via a tube lens (AC254-050-A-ML, Thorlabs, New Jersey, USA), a circular polariser (CP1L532, Thorlabs, New Jersey, USA) and an objective (20 $\times$ , 0.4 NA, RMS20X, Thorlabs, New Jersey, USA). Two types of MMFs including a STIN 105  $\mathrm{\mu }$ m, 0.22 NA) and a GRIN (100  $\mathrm{\mu }$ m, 0.29 NA) fibre with the same length of 20 cm were employed. A sub-region of the DMD covering 128 × 128 micromirrors was used for light modulation. Prior to image acquisition, a fibre characterisation step was performed by a fibre characterisation unit that comprised a CMOS camera (C11440-22CU01, Hamamatsu Photonics, Shizuoka, Japan) for capturing the output speckle patterns after magnification by an objective (20 $\times$ , 0.4 NA, RMS20X, Thorlabs, New Jersey, USA) and a tube lens (AC254-0100-A-ML, Thorlabs, New Jersey, USA). The focal plane of the camera was set to approximately  $100\mathrm{\mu }\mathrm{m}$ away from the distal end of the fibre.