Resolution improvement in laser diode-based pump-probe microscopy with an annular pupil filter

Area of Science:

• Optics and Photonics
• Microscopy Techniques
• Nanotechnology

Background:

• Laser-diode-based pump-probe microscopy is a powerful tool for material analysis.
• Improving lateral resolution is crucial for detailed nanoscale imaging.
• Conventional circular beams can suffer from diffraction-limited resolution and side lobe artifacts.

Purpose of the Study:

• To demonstrate the efficacy of annular beams in enhancing lateral resolution for pump-probe microscopy.
• To quantify the improvement in point-spread function width using annular beams.
• To investigate the suppression of side lobes at the focal plane.

Main Methods:

• Experimental implementation of annular pump-probe beams in a laser-diode-based microscopy setup.
• Characterization of the point-spread function width for both annular and circular beams.
• Measurement of photothermal and stimulated emission signals from nanoparticles and fluorescence beads.

Main Results:

• Annular pump-probe beams achieved a point-spread function width of 162 nm.
• This represents a 30% improvement compared to circular beams (232 nm).
• Efficient suppression of side lobes was observed at the focal plane.

Conclusions:

• Annular beams offer a significant advancement in achieving higher lateral resolution in pump-probe microscopy.
• The demonstrated technique is versatile, applicable to various signal types like photothermal and stimulated emission.
• This method provides a pathway for more precise nanoscale imaging and material characterization.