BACKGROUNDRice cultivation under film mulching with no flooding is widely used as an effective water‐saving technology. Different colors of film mulch have different effects on the soil hydrothermal environment and crop growth because of their different optical properties. However, the effects of different colors of film mulch on soil temperature and rice physiological growth are not clearly understood.RESULTSField experiments were conducted in 2019 and 2020 to investigate the effects of different color mulches on soil temperature and rice growth in a non‐flooded condition. Transparent film (TM), black film (BM), two‐color film (BWM, silver on the front and black on the back), and no film (NM) in a non‐flooded condition were designed. Soil temperature variation at different soil depths of 0–0.25 m and rice plant height, stem thickness, dry matter, yield and quality were monitored. The results showed that compared to no mulching, the mulching treatment effectively increased the average soil temperature during the whole rice growth stage with the soil temperature ranked TM > BM > BWM. Compared with NM, the BM and BWM treatments increased rice yield by 12.1–17.7% and 6.4–14.4% in 2019 and 2020, respectively. The BWM had 18.2% and 6.8% greater gel consistency than NM in 2019 and 2020, respectively.CONCLUSIONTransparent film should be applied with care because of the high soil temperature stress. Black film and two‐color film (silver on the front and black on the back) could be better option for rice yield, increasing and quality improving in a non‐flooded condition. © 2023 Society of Chemical Industry.

As an important parameter in studies on vision and ophthalmology, pupil size directly controls the amount of the light entering the human eye. Pupilometers or eye tracking systems are used to measure the pupil size in some studies while a pupil size estimation model can be applied when actual measurement is not available, such as in cases of optical design, photobiological safety studies, etc. There are several existing pupil size estimation models, most of which reveal the relationship between pupil size and spatial distribution of luminance. However, the radial asymmetry of spatial luminance weighting function in horizontal and vertical directions and the effect of light chromaticity on the human eye were investigated. In this paper, experiments were conducted to reveal the asymmetry of the spatial weighting function in the horizontal and vertical directions and the effect of chromaticity on the pupil size. A unified pupil size estimation model is proposed based on spatially weighted corneal flux density and chromaticity coordinates.

In augmented reality diffractive waveguide technology, the light field needs to be collimated before being transmitted into the diffractive waveguide. Conventional schemes usually require additional collimating optics to collimate the light from the micro-image source and guide it into the waveguide in-coupling elements. In order to meet the needs of head-mounted devices and further miniaturize the equipment, this paper proposes a waveguide device that combines collimation and coupling by using a reflective polarization volume lens (PVL). A related model is also established and simulated to calculate the diffraction and transmission characteristics of the PVL element, and is then improved to fit the experiment. The diffraction lens studied in this paper has high diffraction efficiency with a large off-axis angle, which can fold the optical path and reduce considerably the volume of the optical system when applied to the waveguide system.

As an important index in studies on vision and display technology, pupil size controls the amount of the light entering human eye. Eye tracking systems are normally used to measure the pupil size while a pupil size estimation model can be applied when actual measurement is not available. The weighting functions of the reported pupil size estimation models show radial symmetry, which contradicted the radial asymmetric distribution of photoreceptors on the retina. Chromaticity spatial distribution has not been taken into consideration either. In this paper, the perceptual experiments are carried out with patterned and colored stimuli to evaluate the spatial and color varying effect of luminance to the pupil. A revised corneal flux density is proposed, which shows a high correlation with pupil diameters. Based on this, a pupil size estimation model is proposed. Pupil diameters can be calculated after inputting luminance and chromaticity spatial distribution matrixes. After verification, this model can be applied to indoor scenes with different lighting temperatures within the general illumination range. This model should be useful in scientific and practical applications where pupil diameter matters.

People's perception of brightness and visual comfort in different light environments are important indicators of display products. The perception of the brightness of the human eye is often different from the actual brightness of the display. This is because there is a difference between the perceived brightness and the physical brightness. The luminous body of the same physical brightness may give people different feelings, thus producing different perceived brightness. In the complex optical environment, the existing photoelectric measurement parameters may not be able to accurately describe the perception effect of the display device. The research on perceived brightness and visual comfort has a long history, but in view of the increasingly complex light environment and the development of diversified display equipment, the perceptual brightness model needs to be further modified and improved. Based on the modeling research of perceived brightness, this paper studies the perception mechanism of human eyes, analyzes the shortcomings of the current mainstream or new display devices, and proposes a more comfortable display technology based on people's viewing habits, ambient light and display content.