Single-pixel fluorescent imaging with temporally labeled illumination patterns

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

“…Consequently, CHIRPT imaging is characterized by a coherent spread function (CSF) in space and a coherent transfer function (CTF) in the spatial frequency domain—analogous to the PSF and OTF for LSM. Many of the principle advantages of CHIRPT, such as digital refocusing and aberration correction of fluorescent images, are a direct result of the complex valued CSF that encodes phase variations into temporal modulations of fluorescent light [14,24]. …”

“…Throughout the scan, the AC signal encodes redundant spatial frequency information that must be isolated to recover a unique image of the object. CHIRPT enables the extraction of an SSB without the need to collect multiple images with phase-shifted illumination patterns [13,14]. This is accomplished with a time-dependent phase shift that causes the illumination fringes to shift across the specimen while the spatial frequency of the fringes is scanned through the support of the objective lens [15].…”

“…In that case, the modulation is imparted to an illuminating light beam with a spinning disk that contains a printed pattern [7,13,14]. The illumination is brought to a line focus on the disk, which is then is re-imaged onto the object.…”

“…From that analysis, it follows that CHIRPT will obtain the largest possible DOF for an imaging system because plane waves are eigenfunctions of the Helmholtz equation that describes wave propagation in the object. While the plane-wave model of CHIRPT matches experimental measurements remarkably well [13,14], the focused illumination light that is typically used in the experimental realization of CHIRPT limits the DOF.…”

“…We recently developed an SPI method dubbed coherent holographic image reconstruction by phase transfer (CHIRPT), an imaging technique that converts the spatial phase information carried by the illumination light pattern into temporal modulations of the measured light [13,14]. A key feature of CHIRPT is the ability to digitally refocus light collected from regions that lie well beyond the traditional depth of field (DOF) set by the numerical aperture (NA) of the microscope and illumination wavelength.…”