Figure 2 shows the inverted microscope (Olympus IX71) with excitation and emission detection pathways. Double arrows indicate translating elements in the apparatus with their approximate spatial resolution. The 514.5-nm line from the argon ion laser (Innova 300, Coherent, Santa Clara, CA) is intensity modulated by the acoustoptic modulator (AOM) then linearly polarized by the Glan-Taylor (P) polarizer. The polarization rotator (PR) uses Fresnel Rhombs to rotate linearly polarized light to the desired orientation. Linearly polarized light, split into two beams at the interferometer (IF), travels different path lengths before rejoining. Path length difference is , well under the coherence length of the laser. The lower and upper path beams have relative path difference controlled to precision using a nanopositioning piezo stage and controller (nano-bio 100, MCL, Madison, WI) that translates two mirrors in tandem within the box. The beam expander (BE) consists of a or microscope objective and a large-diameter, long-focal-length (250 mm) lens (LFL). The LFL translates with 25-μm resolution using a motorized micrometer (Newport, Irvine CA). Exciting laser light enters the microscope, reflects at the dichroic mirror (DM), and is focused on the sample by the objective. The objective (Olympus planapo , 1.45 NA, and 100 µm working distance) translates along the optical axis under manual control using the microscope focus and with nanometer precision using a piezo nanopositioner (C-Focus, MCL). Emitted light is collected by the objective, transmitted by the dichroic mirror, then focused by the tube lens (TL) onto the camera (CCD, Orca ER, Hamamatsu Photonics, Hamamatsu-City, Japan). A microscope stage with leadscrew drives and stepper motors translates the CCD camera with submicrometer resolution (LEP, Hawthorne, NY).