In a examine revealed in Proceedings of the Nationwide Academy of Sciences, a analysis crew led by Prof. Dongguo Zhang of the College of Science and Expertise of China (USTC) of the Chinese language Academy of Sciences (CAS) developed an optical module consisting of cascaded momentum-space polarization filters primarily based on vector mild area modulation.
This optical module successfully suppresses background noise whereas capturing excessive signal-to-noise ratio (SNR) microscopy pictures of particular person nano-objects.
Exact imaging of the evolution and movement habits of particular person nano-objects, corresponding to ultrafine atmospheric particles, is essential on the subject of understanding their functionalities and properties. Label-free optical microscopy has been extensively utilized in imaging and sensing of nanoparticles resulting from its distinctive non-destructive, non-invasive and quick detection traits.
Nevertheless, the power of sunshine scattering by particular person nanoparticles in air drops considerably with particle measurement to the sixth energy. Consequently, the scattered mild depth is considerably decrease than the background noise, making it tough for conventional label-free optical microscopes to perform excessive SNR imaging of particular person nanoparticles.
To handle this challenge, Prof. Zhang’s crew developed a momentum-space polarization filter that can be utilized to switch vector area polarization.
Solely scattering mild from single nano-objects can move by way of the filter and be caught by the detector, whereas various background noise is considerably filtered and suppressed, due to this fact reaching excessive distinction and excessive SNR imaging of nano-objects.
The filter was positioned on the exit finish of a complete inner reflection microscopy (TIRM) to indicate how it’s used. Compared to conventional label-free black-field microscopy, black-field microscopy, which has diminished (blacker) background noise and better detection sensitivity, was achieved by changing TIRM into black-field microscopy as soon as the filter was put in.
As such, it was made clear that black-field microscopy can be utilized to acquire real-time excessive SNR and high-contrast optical microscopy pictures of particular person protein molecules, gold nanoparticles, and perovskite nanocrystals.
Moreover, single perovskite nanocrystals endure anion-exchange reactions upon the sequential introduction of HCl and HI vapor. These processes alter the nanocrystals’ form and refractive index, therefore inflicting variations within the scattered mild alerts of the person nanocrystals.
Black-field microscopy can seize this course of in real-time, providing a novel photonic approach for the detection of bodily and chemical reactions going down as a nanoobject’s properties evolve.
The momentum-space polarization filter machine is exclusive in that it may be used to supply black-field imaging functionality to traditional label-free optical microscopy, together with floor plasmon resonance microscopy (SPRM), TIRM, and different near-field optical microscopy, with out altering the interior construction of the microscopes. This enormously will increase the sensitivity of the microscopes in detecting particular person nano-objects.
In abstract, the crew created a novel platform for analyzing particular person nanoparticles utilizing black-field microscopy, which holds important promise to be used within the fields of supplies science, biology, physics, and environmental science.
Journal Reference:
Liu, Y., et. al. (2024) Cascaded momentum-space polarization filters enabled label-free black-field microscopy for single nanoparticles evaluation. Proceedings of the Nationwide Academy of Sciences. doi:10.1073/pnas.232182512