Superresolved multiphoton microscopy with spatial frequency-modulated imaging

Abstract

Superresolved far-field microscopy has emerged as a powerful tool for investigating the structure of objects with resolution well below the diffraction limit of light. Nearly all superresolution imaging techniques reported to date rely on real energy states of fluorescent molecules to circumvent the diffraction limit, preventing superresolved imaging with contrast mechanisms that occur via virtual energy states, including harmonic generation (HG). We report a superresolution technique based on spatial frequencymodulated imaging (SPIFI) that permits superresolved nonlinear microscopy with any contrast mechanism and with single-pixel detection. We show multimodal superresolved images with twophoton excited fluorescence (TPEF) and second-harmonic generation (SHG) from biological and inorganic media. Multiphoton SPIFI (MP-SPIFI) provides spatial resolution up to 2η below the diffraction limit, where η is the highest power of the nonlinear intensity response. MP-SPIFI can be used to provide enhanced resolution in optically thin media and may provide a solution for superresolved imaging deep in scattering media.superresolution | harmonic generation | multiphoton microscopy

Three-dimensional single-pixel imaging of incoherent light with spatiotemporally modulated illumination

“…Moving forward, we will disregard this component of the signal since it does not contribute to image formation. We note, however, that the DC intensity does contribute to the overall noise measured in the total signal, S t , and thus contributes to the SNR of the recovered image [15]. …”

“…Instead, an SSB is isolated by a time-dependent phase shift imparted to the illumination intensity that manifests as a carrier frequency in the temporal domain. This carrier frequency permits one to isolate all three components of the measured signal—$S_t^{\left(0\right)},S_t^{\left(1\right)}, \text{and} S_t^{\left(-1\right)}$ —with straightforward Fourier signal processing methods [13–15,23]. …”

Analysis of Anorthite Dissolution on the Submicrometer Scale

“…Tests will entail adding a fluorescing Ca 2+ indicator to the flow solution and conducting laser imaging during flow through experiments to capture Ca 2+ release during dissolution. SPIFI has been used with TPEF and with second-harmonic generation (SHG) to image inorganic and biological samples [6,7]. However, this would be the first time in-situ geochemical dissolution has been captured with SPIFI.…”

Third-harmonic generation at interfaces with femtosecond pulses: self-focusing contribution and nonlinear microscopy

“…In this way, the spatial location is encoded by the Recently, it was demonstrated that using the SPIFI microscope it is possible to obtain images in superresolution (sub-diffraction-limit). 18 When the laser beam passes through the time-dependent spatial modulation pattern, produced by the spinning disk rotation (or, as in our case, by the SLM modulation), the line focus is diffracted into several beams with varying propagation angles, θ j , where j corresponds to the diffracted order, Fig. 7.2.…”

“…81 Recently, SPIFI has been shown to have the added benefit of superresolved multimodal imaging. 18 Multiphoton SPIFI provides spatial resolution up to 2β below the diffraction limit, where β is the highest power of the nonlinear irradiance response, for instance, β = 4 for SHG and β = 6 for THG. Michael we improved the microscope's design and took third-harmonic images for the first time using a SPIFI setup.…”