Aberration free synthetic aperture second harmonic generation holography.

Second harmonic generation (SHG) microscopy is a valuable tool for optical microscopy. SHG microscopy is normally performed as a point scanning imaging method, which lacks phase information and is limited in spatial resolution by the spatial frequency support of the illumination optics. In addition, aberrations in the illumination are difficult to remove.

Cascaded domain multiphoton spatial frequency modulation imaging.

Significance: Multiphoton microscopy is a powerful imaging tool for biomedical applications. A variety of techniques and respective benefits exist for multiphoton microscopy, but an enhanced resolution is especially desired. Additionally multiphoton microscopy requires ultrafast pulses for excitation, so optimization of the pulse duration at the sample is critical for strong signals.

Super-resolution computational saturated absorption microscopy.

Imaging beyond the diffraction limit barrier has attracted wide attention due to the ability to resolve previously hidden image features. Of the various super-resolution microscopy techniques available, a particularly simple method called saturated excitation microscopy (SAX) requires only simple modification of a laser scanning microscope: The illumination beam power is sinusoidally modulated and driven into saturation. SAX images are extracted from the harmonics of the modulation frequency and exhibit improved spatial resolution.

Single-shot spatial frequency modulation for imaging.

Spatial frequency modulation for imaging (SPIFI) has traditionally employed a time-varying spatial modulation of the excitation beam. Here, for the first time to our knowledge, we introduce single-shot SPIFI, where the spatial frequency modulation is imposed across the entire spatial bandwidth of the optical system simultaneously enabling single-shot operation.

Nearly degenerate two-color impulsive coherent Raman hyperspectral imaging.

Impulsive stimulated Raman scattering (ISRS) is a robust technique for studying low frequency (<300 cm) Raman vibrational modes, but ISRS has faced difficulty in translation to an imaging modality. A primary challenge is the separation of the pump and probe pulses. Here we introduce and demonstrate a simple strategy for ISRS spectroscopy and hyperspectral imaging that uses complementary steep edge spectral filters to separate the probe beam detection from the pump and enables simple ISRS microscopy with a single-color ultrafast laser source.

Fisher information and the Cramér-Rao lower bound in single-pixel localization microscopy with spatiotemporally modulated illumination.

Single-pixel imaging, the concept that an image can be captured via a single-pixel detector, is a cost-effective yet powerful technique to reduce data acquisition duration without sacrificing image resolution when properly structured illumination patterns are introduced. Normally, the image reconstruction process is subject to the diffraction limit. Here, we study the possibility of exploiting the information contained in the illumination patterns to enable a form of single-pixel localization microscopy (SPLM) for super-resolution.

Two-dimensional random access multiphoton spatial frequency modulated imaging.

Spatial frequency modulated imaging (SPIFI) enables the use of an extended excitation source for linear and nonlinear imaging with single element detection. To date, SPIFI has only been used with fixed excitation source geometries. Here, we explore the potential for the SPIFI method when a spatial light modulator (SLM) is used to program the excitation source, opening the door to a more versatile, random access imaging environment.

Interferometric spatial frequency modulation imaging.

Interferometric spatial frequency modulation for imaging (I-SPIFI) is demonstrated for the first time, to our knowledge. Significantly, this imaging modality can be seamlessly combined with nonlinear SPIFI imaging and operates through single-element detection, making it compatible for use in scattering specimens. Imaging dynamic processes with submicrometer axial resolution through long working distance optics is shown, and high contrast images compared to traditional wide-field microscopy images.

Fabrication and characterization of modulation masks for multimodal spatial frequency modulated microscopy.

Spatial frequency modulated imaging (SPIFI) is a powerful imaging method that when used in conjunction with multiphoton contrast mechanisms has the potential to improve the spatial and temporal scales that can be explored within a single nonlinear optical microscope platform. Here we demonstrate, for the first time to our knowledge, that it is possible to fabricate inexpensive masks using femtosecond laser micromachining that can be readily deployed within the multiphoton microscope architecture to transform the system from a traditional point-scanning system to SPIFI and gain the inherent advantages that follow.

High-resolution mosaic imaging with multifocal, multiphoton photon-counting microscopy.

High-resolution mosaic imaging is performed for the first time to our knowledge with a multifocal, multiphoton, photon-counting imaging system. We present a novel design consisting of a home-built femtosecond Yb-doped KGdWO(4) laser with an optical multiplexer, which is coupled with a commercial Olympus IX-71 microscope frame. Photon counting is performed using single-element detectors and an inexpensive electronic demultiplexer and counters.