Multi-wavelength confocal displacement sensing using a highly dispersive flat-field concave grating.

A multi-wavelength confocal displacement sensor based on a flat-field concave grating (FFCG) was proposed and designed; the large dispersion and small volume of the FFCG make it an ideal candidate for replacing the complex dispersive lens group. The designed displacement sensor was calibrated by displacement meter, and the characteristics were measured. Consequently, for the proposed displacement sensor, the displacement range of 6.8 mm was measured with the R-square linearity evaluation coefficient of 0.998, and the sensitivity preceded 17.1 nm/mm. The resolution of the displacement sensor was characterized by 70 µm, as well as a full width at half maximum (FWHM) fluctuating around 1.63 nm, indicating high precision and accuracy in displacement measurement. Moreover, the stability and reliability of the sensor were verified within 20 min, with no significant wavelength shifts, and gentle power fluctuations of 557.73 counts at 520 nm and 563.67 counts at 545.05 nm, respectively.

Target-surface multiplexed quantitative dynamic phase microscopic imaging based on the transport-of-intensity equation.

Microscopic phase digital imaging based on the transport of intensity equation, known as TIE, is widely used in optical measurement and biomedical imaging since it can dispense with the dependence of traditional phase imaging systems on mechanical rotational scanning and interferometry devices. In this work, we provide a single exposure target-surface multiplexed phase reconstruction (SETMPR) structure based on TIE, which is remarkably easy to construct since it directly combines a conventional bright-field inverted microscope with a special image plane transmission structure that is capable of wavefront shaping and amplification. In practice, the SETMPR is able to achieve dynamic, non-interferometric, quantitative refractive index distribution of both static optical samples and dynamic biological samples in only one shot, meaning that the only limitation of measuring frequency is the frame rate. By comparing the measurement results of a microlens array and a grating with a standard instrument, the quantitative measurement capability and accuracy are demonstrated. Subsequently, both in situ static and long-term dynamic quantitative imaging of HT22 cells were performed, while automatic image segmentation was completed by introducing machine learning methods, which verified the application prospect of this work in dynamic observation of cellular in the biomedical field.