A technique using Linnik-based optical coherence microscopy (OCM), with built-in fluorescence microscopy (FM), is demonstrated here to describe cellular-level morphology for fresh porcine and biobank tissue specimens. The proposed method utilizes color-coding to generate digital pseudo-H&E (p-H&E) images. Using the same camera, colocalized FM images are merged with corresponding morphological OCM images using a 24-bit RGB composition process to generate position-matched p-H&E images. From receipt of dissected fresh tissue piece to generation of stitched images, the total processing time is <15 min for a 1-cm2 specimen, which is on average two times faster than frozen-section H&E process for fatty or water-rich fresh tissue specimens. This technique was successfully used to scan human and animal fresh tissue pieces, demonstrating its applicability for both biobank and veterinary purposes. We provide an in-depth comparison between p-H&E and human frozen-section H&E images acquired from the same metastatic sentinel lymph node slice (∼10 µm thick), and show the differences, like elastic fibers of a tiny blood vessel and cytoplasm of tumor cells. This optical sectioning technique provides histopathologists with a convenient assessment method that outputs large-field H&E-like images of fresh tissue pieces without requiring any physical embedment.

No abstract

Intense nanosecond emission with spectral broadening from 980 to 1600 nm was generated with peak power up to 117 kW, close to the damage threshold of fiber fuse. Both laser amplification and nonlinear conversion were simultaneously employed in a fiber power amplifier giving power scaling free from significant depletion. In a diode-seeded all-PM-fiber master oscillation power amplifier system under all normal dispersion, a core-pumped preamplifier using double-pass scheme can significantly improve the energy extraction. This produced the pulse energy of 1.2 mJ and duration of 6 ns with a conversion efficiency of 66% at the moderate repetition of 20 kHz, which is consistent with the coupled laser rate equations including the stimulated Raman scattering. For the comparable nonlinear strength in each stage from single to few modes, the onset and interplay of four kinds of fiber nonlinearities can be addressed.