Vzm 600i

To demonstrate the ultrasonic virtual relay imaging in transmission mode, we built a custom experimental setup consisting of a top microscope assembly and the piezoelectric transducer immersed in a water tank. The cylindrical transducer surrounds the target medium and launches standing pressure waves into it. The top microscope is used in transmission mode for imaging the relayed image through the ultrasonically sculpted virtual GRIN lens. The top microscope is composed of a zoom imaging lens (VZM 600i, Edmund Optics, Inc., USA), a CMOS camera (BFS-U3-51S5C-BD2, FLIR Integrated Imaging Solutions, Inc., Richmond, British Columbia, Canada), and a fluorescent emission filter (MF525-39, Thorlabs, Inc., Newton, New Jersey, USA). A clear glass optical window (WG11050-A, Thorlabs, Inc., Newton, New Jersey, USA) is immersed in the medium and acts as the interface between the microscope and the imaged medium. We designed a fluorescent target object consisting of a negative transparency mask (CAD/Art Services, Inc., Bandon, Oregon, USA) of the word “CMU” (overall size: 374 × 110 µm, minimum feature size: 22 µm) overlaid on a layer of solid agar (A5306, Sigma–Aldrich, Inc., St. Louis, Missouri, USA) homogeneously mixed with Fluorescein dye. the sample is illuminated by a blue laser (λ_light = 473 nm) from the bottom.

The measurement setup (Supplementary Fig. 1) consists of a microforce sensing probe (FT-S100, range ± 100 µN and FT-S1000, range ± 1000 µN; FemtoTools AG, Switzerland) and a data acquisition board (NI USB-6351, National Instruments Inc., USA) that was used to collect data at 100 Hz with custom-built software; motorized high-precision positioning stages for x-direction (M-404.8PD, 0.50 µm precision, Physik Instrumente GmbH, Germany), y-direction (M-122.2DD, 0.15 µm precision, Physik Instrumente GmbH, Germany), and z-direction (M-111.1DG, 0.10 µm precision, Physik Instrumente GmbH, Germany); a piezoelectric microdispenser (PicPIP, 100 pl minimum droplet size, GeSiM GmbH, Germany); a high-speed camera sideview (Phantom Miro LC310, Vision Research Inc., USA) with a 1–5× macro lens (MP-E 65, Canon Inc., Japan) and another CCD camera sideview (IGV B1320M, Imperx Inc., USA) with a 1–6× microscope lens (VZM 600i, Edmund Optics Inc., USA). Measurements were carried out in room temperature (~22 °C) and in ~40% relative humidity.