Optical-resolution photoacoustic microscopy with a needle-shaped beam

• Published in: Nature photonics 2023-01, Vol.17 (1), p.89-95
• Main Authors: Cao, Rui, Zhao, Jingjing, Li, Lei, Du, Lin, Zhang, Yide, Luo, Yilin, Jiang, Laiming, Davis, Samuel, Zhou, Qifa, de la Zerda, Adam, Wang, Lihong V.
• Format: Article
• Language: English
• Subjects: 142/126; 639/624/1107/328; 639/624/1107/510; Applied and Technical Physics; Depth of field; Diffractive optical elements; Histology; Image acquisition; Image quality; Image resolution; Medical imaging; Microscopes; Microscopy; Neuroimaging; Optical components; Photoacoustic microscopy; Physics; Physics and Astronomy; Quantum Physics; Sidelobes
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-022-01112-w

Optical-resolution photoacoustic microscopy can visualize wavelength-dependent optical absorption at the cellular level. However, this technique suffers from a limited depth of field due to the tight focus of the optical excitation beam, making it challenging to acquire high-resolution images of samples with uneven surfaces or high-quality volumetric images without z scanning. To overcome this limitation, we propose needle-shaped beam photoacoustic microscopy, which can extend the depth of field to around a 28-fold Rayleigh length via customized diffractive optical elements. These diffractive optical elements generate a needle-shaped beam with a well-maintained beam diameter, a uniform axial intensity distribution and negligible sidelobes. The advantage of using needle-shaped beam photoacoustic microscopy is demonstrated via both histology-like imaging of fresh slide-free organs using a 266 nm laser and in vivo mouse-brain vasculature imaging using a 532 nm laser. This approach provides new perspectives for slide-free intraoperative pathological imaging and in vivo organ-level imaging. The use of a needle-shaped optical beam improves the depth of field for photoacoustic imaging.