Virtually all optical microscopes for biological imaging are based on refractive objective lenses. The performance of these lenses approaches the theoretical limit, however, their use is limited to the visible to near-infrared spectral range. Even within this range, their performance is only guaranteed over a relatively narrow range, and broadband use is invariably affected by chromatic aberrations. Another problem is the group delay dispersion that these lenses introduce to short optical pulses, which reduces the efficiency of nonlinear optical (NLO) signal generation in the microscope. Taken together, these shortcomings seriously compromise the imaging properties of several NLO imaging modalities such as three-photon excited fluorescence and third-harmonic generation. In addition, refractive objectives simply cannot be used for NLO techniques that incorporate excitation light in the mid-infrared (MIR) range, such as photothermal imaging and sum-frequency generation, promising technologies based on MIR molecular contrast. The only viable alternative is the all-reflective Schwarzschild-Cassegrain (SC) objective, which is inherently achromatic but suffers from a non-ideal point spread function and a center obscuration that limits throughput. Because of these limitations, SC lenses have not found widespread use in biological imaging applications. This lack of performance is also the reason why advances in exciting new MIR-based NLO imaging technologies have been stifled: there simply are no high-performance high numerical focusing options available to support these emerging imaging technologies. In this project, we develop a novel high numerical aperture lens that overcomes all limitations of the SC focusing lens. Leveraging refractive and reflective elements based on a non- concentric layout, this new catadioptric design features transmission from the ultra-violet to the mid-infrared, exhibits a wide field of view and extended working distance, dramatically reduces group delay dispersion and significantly improves throughput by eliminating the center obscuration all together. This lens not only advances existing NLO modalities that rely on broadband radiation, but also enables new technologies such as photothermal imaging and SFG microscopy that have thus far suffered from low performance focusing optics. Ultimately, this imaging tool will enable researchers to perform single-cell and tissue studies for a variety of cross- cutting biomedical applications regardless of the illumination source used.
Public Health Relevance Statement: Project Narrative. In this project, we design, fabricate, and validate a new type of microscope objective, namely a catadioptric objective lens in a non-concentric geometry. This lens overcomes all limitations of commercial reflective objectives, which are invariably based on the Schwarzschild-Cassegrain design. The new lens features spectrally broad operation from the ultraviolet to the mid-infrared, a wide field of view, unparalleled throughput and a well-behaved point spread function, thus enabling new and advanced nonlinear optical technologies that have so far been stifled by the lack of a high-performance objective lens. To support such innovation, we unite a team of expert microscopists and optical engineers to prototype and validate this lens through multimodal imaging of tissue biopsies at the single-cell level.
Project Terms: Fatty Tissue; adipose; white adipose tissue; yellow adipose tissue; Adipose tissue; Affect; Astronomy; space science; Biopsy; Cells; Cell Body; Color; Dermis; Corium; Cutis; Electromagnetics; Elements; Engineering; Exhibits; Fluorescence; Housing; Light; Photoradiation; Lighting; Illumination; Lipids; Methods; Microscopy; Mus; Mice; Mice Mammals; Murine; Optics; optical; Research Personnel; Investigators; Researchers; Signal Transduction; Cell Communication and Signaling; Cell Signaling; Intracellular Communication and Signaling; Signal Transduction Systems; Signaling; biological signal transduction; Computer software; Software; Technology; Testing; Tissues; Body Tissues; Collagen Type I; Type 1 Collagen; Diamond; County; Generations; Imaging Techniques; Imaging Procedures; Imaging Technics; Photons; Microscope; improved; Surface; Specified; Specific qualifier value; Phase; biologic; Biological; Chemicals; Measurement; tool; instrument; Specimen; Research Specimen; Physiologic pulse; Pulse; Frequencies; Source; Techniques; System; Performance; novel; new technology; novel technologies; Modality; Radiation; Deterioration; Property; Oranges; image-based method; imaging method; imaging modality; preventing; prevent; Address; Imaging Device; Imaging Instrument; Imaging Tool; Multimodal Imaging; multi-modal imaging; multi-modality imaging; multimodality imaging; Resolution; resolutions; Sum; Collection; transmission process; Transmission; Molecular; Development; developmental; ultraviolet; ultra violet; Image; imaging; optic imaging; optical imaging; 2-photon; two-photon; virtual; designing; design; Outcome; Imaging technology; innovate; innovative; innovation; usability; prototype; lenses; lens; multi-modality; multimodality; flexible; flexibility; operations; operation; Geometry; contrast imaging; Tissue imaging; high resolution imaging; imaging properties; multiphoton excitation microscopy; multiphoton microscopy; biomedical imaging; supply chain; fabrication
