Versatile high-speed confocal microscopy using a single laser beam

TL;DR

This paper introduces a versatile high-speed confocal microscope using a single laser beam and a dual 2D scanning system, achieving high frame rates, reduced phototoxicity, and compatibility with particle tracking for 3D dynamics.

Contribution

The paper presents a novel confocal microscopy design that combines a single laser beam with a dual 2D scan system for high-speed imaging and integration with particle tracking.

Findings

Achieves frame rates up to 32kHz line rate.

Lateral resolution of 0.235 micrometers.

Reduces phototoxicity and bleaching.

Abstract

We present a new flexible high speed laser scanning confocal microscope and its extension by an astigmatism particle tracking device (APTV). Many standard confocal microscopes use either a single laser beam to scan the sample at relatively low overall frame rate, or many laser beam to simultaneously scan the sample and achieve a high overall frame rate. Single-laser-beam confocal microscope often use a point detector to acquire the image. To achieve high overall frame rates, we use, next to the standard 2D probe scanning unit, a second 2D scan unit projecting the image directly on a 2D CCD-sensor (re-scan configuration). Using only a single laser beam eliminates cross-talk and leads to an imaging quality that is independent of the frame rate with a lateral resolution of 0.235\unit{\mu m}. The design described here is suitable for high frame rate, i.e., for frame rates well above video rate (full frame) up to a line rate of 32kHz. The dwell time of the laser focus on any spot in the sample (122ns) is significantly shorter than in standard confocal microscopes (in the order of milli or microseconds). This short dwell time reduces phototoxicity and bleaching of fluorescent molecules. The new design opens further flexibility and facilitates coupling to other optical methods. The setup can easily be extended by an APTV device to measure three dimensional dynamics while being able to show high resolution confocal structures. Thus one can use the high resolution confocal information synchronized with an APTV dataset.