Wavefront coding image reconstruction via physical prior and frequency attention.

Wavefront coding (WFC) is an effective technique for extending the depth-of-field of imaging systems, including optical encoding and digital decoding. We applied physical prior information and frequency domain model to the wavefront decoding, proposing a reconstruction method by a generative model. Specifically, we rebuild the baseline inspired by the transformer and propose three modules, including the point spread function (PSF) attention layer, multi-feature fusion block, and frequency domain self-attention block. These models are used for end-to-end learning to extract PSF feature information, fuse it into the image features, and further re-normalize the image feature information, respectively. To verify the validity, in the encoding part, we use the genetic algorithm to design a phase mask in a large field-of-view fluorescence microscope system to generate the encoded images. And the experimental results after wavefront decoding show that our method effectively reduces noise, artifacts, and blur. Therefore, we provide a deep-learning wavefront decoding model, which improves reconstruction image quality while considering the large depth-of-field (DOF) of a large field-of-view system, with good potential in detecting digital polymerase chain reaction (dPCR) and biological images.

Quantitative analysis on self-focusing properties of H-PDLC flexible curved radius gratings.

In general, the shape of traditional holographic grating is fixed and immutable, the period will not change after fabrication, this means that the modulation effect on the light field is unalterable. However, traditional grating cannot satisfy all requirements of current optical systems. In order to increase the versatility of holographic grating, a flexible curved radius grating (FCRG) which consists of holographic polymer-dispersed liquid crystal (H-PDLC) was proposed. The FCRG has an important self-focusing property that it can be adjusted the focal length by changing its own radius of curvature correspondingly. In this paper, we use the scalar diffraction theory to analysis the interference and diffraction processes for FCRG under different conditions, then a relationship equation has been deduced to express quantitatively about FCRG between its radius and focal length. According to the relationship, a tunable holographic element is achieved for the function of mechanically-controlled self-focusing effect. Experiments show that the FCRG has two conjugated focusing effects on the positive first-order and negative first-order, both two effects can achieve focus-adjusted ability by changing their radius of curvature. The FCRG provides a way for the coupler of curved waveguide display system for augmented reality in the future.

A rapid nucleic acid concentration measurement system with large field of view for a droplet digital PCR microfluidic chip.

Droplet digital polymerase chain reaction (ddPCR) is an effective technique, with unparalleled sensitivity, for the absolute quantification of target nucleic acids. However, current commercial ddPCR devices for detecting the gene chip are time consuming due to complex image stitching. To address this issue, we propose a universal concentration determination system and realize one-time gene chip imaging with high resolution. All the functional units are controlled by self-developed software using the PyQt5 module in Python. Without stitching technology, images of the ddPCR chip (28 mm × 18 mm) containing 20 000 independent 0.81 nL micro chambers can be obtained in less than 15 seconds, which saves about 165 seconds. A white laser light source (2 mW cm-2) was employed as a substitute for the mercury lamp. Its wavelength matches well with typical fluorescent dyes (e.g., HEX, ROX and Cy5), and thus it can strengthen the fluorescence intensity for weak signals. The results also demonstrated that the correlation coefficient for the measured concentration and theoretical value was above 99%, by testing the ddPCR products with COVID-19 virus. Such a system can greatly reduce the time required for image acquisition and DNA concentration determination, and thus is able to speed up the lab-to-application process for ddPCR technology.

Switchable pupil expansion propagation using orthogonal superposition varied-line-spacing H-PDLC gratings in a holographic waveguide system.

To solve the problem of small field of view in traditional holographic waveguides, this paper proposes a waveguide-coupling technique using orthogonal superposition varied-line-spacing (VLS) gratings. These gratings expand the x and y directions and orthogonally superimpose to achieve transmission in a waveguide and enlarge the pupil field of view. At the optical coupling input end and the coupling output end of a waveguide, one-dimensional VLS gratings are used to realize horizontal expansion of the image. Then a vertical VLS grating is orthogonally superimposed at the exit end to realize vertical expansion of the image. Finally, the waveguide transmission and expansion of the image are completed. In the experiment, holographic polymer dispersed liquid crystal one-dimensional VLS gratings in the x and y directions are fabricated and coupled with a waveguide. An image source with a diameter of 0.5 cm is waveguide-transferred and coupled out, and then passed through the vertical grating. Amplification is performed to obtain an expanded image of a diameter of 2.28 cm. In this study, the diffraction characteristics of the grating used to realize pupil expansion in the holographic waveguide system are analyzed and simulated. It is calculated that the diffraction efficiency of the VLS gratings can reach 80% or more in the 532 nm band. Additionally, the characteristics of an electronically controlled switch are studied. Experimental results show that the method can be used for expanding the field of view and can be applied to waveguide systems for image transmission and expansion.

Achiral polyamine-induced chiral zinc gallophosphates with fused double helix-like strands exhibiting blue to green photoluminescence.

This study found non-chiral polyamines to be effective in inducing chiral frameworks. Four zinc gallophosphates with a chiral UCSB-7 topology were generated from the use of four different linear-chain polyamines as templates. In the structure, helical inorganic strands and templates appeared to fuse into a double helix-like arrangement. Notably, they are the first chiral frameworks to display optical analogues and intriguing photoluminescence properties.

Influence of traditional Chinese medicine constitution type on the susceptibility of hypertensive cases to intracerebral haemorrhage.

OBJECTIVE: To explore the influence of Chinese medicine constitution type on the susceptibility of hypertensive patients to intracerebral haemorrhage. METHODS: Primary hypertensive patients were studied and divided into the hypertension and the hypertensive intracerebral haemorrhage groups, depending on whether or not the patients had intracerebral haemorrhage. The demographic characteristics, physiological characteristics, living habits, biochemical tests, other chronic diseases, Chinese medicine constitution type, etc. were collected and compared between the two groups. The neurological deficit in the hypertensive intracerebral haemorrhage group was also compared among the different constitution types. RESULTS: A total of 304 patients participated in this investigation, including 213 cases in the hypertension group and 91 cases in the hypertensive intracerebral haemorrhage group. The percentages of dampness-heat and qi-depression types in the intracerebral haemorrhage group were greater than those with the same types in the hypertension group (20.9% vs 6.1%, 22.0% vs 8.0%; P<0.05). The percentages of each constitution type were different between genders in both groups. In addition, there were more male cases (14/20) with qi-depression type and more female cases (7/8) with phlegm-dampness type in the hypertensive intracerebral haemorrhage group than those with the same types (3/17 and 9/34, respectively) in the hypertension group (P<0.05). The cases with phlegm-dampness and qi-depression types had greater levels of blood lipids in the intracerebral haemorrhage group than those with the same types in the hypertension group (P<0.05). Furthermore, the cases with the qi-deficiency type presented with a more severe neurological deficit than those with the other types (P<0.05). CONCLUSIONS: Chinese medicine constitution type might have an impact on the susceptibility of hypertensive patients to have an intracerebral haemorrhage. The heat-dampness and qi-depression types might lead to greater susceptibility than the other types. In addition, the patient's gender and blood lipids might also influence the susceptibility along with the constitution type.