Fig. 1 |. A schematic of HOT and the procedure of complex field retrieval.

a, The HOT optical set-up; the system records the complex SHG field by using off-axis holography. BBO, a beta-barium borate crystal; DM, dichroic mirror; DL, delay line; CL, condenser lens; OL, objective lens; F, filter; BS, non-polarized beam splitter; TL, tube lens; CAM, camera. A detailed description of the system design is provided in the Methods. b, A representative hologram recorded by HOT. The sample is a tissue slice of a rabbit lymph node measured in focus. c, The spatial power spectrum of the image in b. One of the sidebands (indicated by the circular dashed line) is isolated and shifted to the origin of the frequency domain. d, The amplitude of the SHG field, extracted from the inverse Fourier transform of c. e, The phase of the SHG field. Scale bars, 10 μm.