A low cost non-linear fluorescence near-field/far-field microscope

Presented is a microscope design that employs two-photon non-linear excitation to allow the imaging of the fluorescence from almost any visible fluorophore at resolutions below 30 nm without changing filters or excitation wavelength. The ability of the microscope to image samples at atmospheric pressure, room temperature, and in solution makes it a very promising tool for the biological and materials science communities. The microscope demonstrates the ability to image topographical, far-field and near-field optical responses from the sample of interest. A single computer, simple custom control circuits, field programmable gate array (FPGA) data acquisition, and a simplified custom optical system are used. This versatility enables the end user to custom-design experiments from confocal far-field single molecule imaging to high resolution scanning probe microscopy imaging. Demonstrated is the far-field, topographic and near-field imaging using two-photon excitation of Bovine Pulmonary Artery Endothelial (BPAE) cells and J-aggregates (PVS Poly vinyl Sulfate) and PIC (Pseudo-Isocyanine) dye.