High-speed line-scan confocal Raman microscope with enhanced diffraction efficiency

Abstract

Confocal Raman microscopy is commonly employed across different research fields because it allows for label-free sample investigation at high spatial resolution. However, the slow data acquisition speed of Raman microscopy limits its application for imaging large area samples. We developed a line-scan confocal Raman microscope to achieve parallel detection for high-speed data acquisition and proposed a dual mirror scan method to enhance the diffraction efficiency of the spectrometer. We used a Powell lens for the line illumination and demonstrated that it can provide a more uniform intensity distribution than a cylindrical lens. The spectrometer consists of a volume phase holographic grating and two scanning mirrors. Using the proposed dual mirror scan method can provide a high-resolution Raman spectrum at high efficiency over a wide spectral range. The system has a maximum spectral rate of 25 600 spectra s−1 and a theoretical spectral resolution of 1.2 cm−1. With the parallel detection by the line illumination and the enhanced diffraction efficiency, we expect the proposed system can be used in a variety of applications that require a high spectral rate, such as wide-field Raman imaging.

Histological classification of atherosclerotic arteries using high‐speed confocal Raman microscopy with machine learning

“…The samples were imaged with a custom-built confocal Raman microscopy as previously described [18]. Briefly, the instrument was equipped with a 532 nm laser with a spectral bandwidth of 1 MHz (Torus 532, Laser Quantum Ltd, Cheshire, UK).…”

“…However, Raman imaging requires a long exposure time due to weak Raman scattering signals and high spectral resolution over a wide spectral range. To overcome this limitation, our group has previously developed confocal Raman microscopy for high speed and spectral resolution [18]. In order to increase the imaging speed, a line illumination was used with a Powell lens for higher uniformity compared to a cylindrical lens.…”

Fast Raman imaging through the combination of context-aware matrix completion and low spectral resolution

“…21,23 In spontaneous Raman imaging, multifocal methods (ranging from traditional line-scan imaging, to more exotic methods) have been proposed. [25][26][27][28][29][30][31] While these methods improve imaging speed, they come at the cost of somewhat increased system complexity, as well as reduced confocal sectioning ability, which can be important for limiting sources of background, such as from glass coverslips that fluoresce at the common 785 nm excitation wavelengths.…”