Specifically, two azimuth detectors arranged perpendicular to each other can realize 3D light-direction sensing and determine the azimuth angle φ and elevation angle θ of the incident light in spherical coordinates. When incident light strikes patterned nanocrystals, the azimuth angle α between the incident light and the reference plane can be detected by measuring the colour output of the basic unit (Fig. The basic unit of 3D light-field sensor is a single azimuth detector comprising multicolour-emitting perovskite nanocrystals. A 3D light-field sensor can then be constructed by integrating the patterned thin-film substrate with a colour charge-coupled device (CCD) that converts the angle of incident light rays into a specific colour output. A fundamental design for a 3D light-field detection involves lithographically patterning perovskite nanocrystals onto a transparent substrate (Fig. Furthermore, Sn-based perovskite nanocrystals can have optical bandgaps that extend into the near-infrared light region 36, 37.
They also demonstrate highly efficient and tunable emission with high colour saturation across the visible spectrum under X-ray or visible-light irradiation. To test our hypothesis, we selected inorganic perovskite nanocrystals because of their excellent optoelectronic properties 32, 33, 34, 35. Owing to the versatility of colour encoding in data visualization, we proposed that colour-contrast encoding could be used to visualize the directions of light rays. Although several sensors using Shack–Hartmann or Hartmann structures are capable of phase measurements in the extreme ultraviolet-light range, phase measurements of hard X-rays and gamma rays remain challenging because high-energy beams cannot be focused using conventional mirrors or microlenses 30, 31. Moreover, light-vector detection and control are at present limited to ultraviolet- and visible-light wavelengths. However, most of them depend on wavelength or polarization and require materials with a high refractive index 29. Optical resonances in subwavelength semiconductor structures enable the development of angle-sensitive structures by manipulating light–matter interactions 23, 24, 25, 26, 27, 28. Nevertheless, integration of these elements into complementary metal-oxide-semiconductor architectures is costly and complex 4, 20, 21, 22. An optical array of microlenses or photonic crystals with pixelated photodiodes is usually used to measure the light field or the distribution of light directions and thus to characterize phase information. Although intensity information alone is sufficient for conventional applications such as two-dimensional photography and microscopy imaging, this limitation hinders three-dimensional (3D) and four-dimensional imaging applications, including phase-contrast imaging, light detection and ranging, autonomous vehicles, virtual reality and space exploration 11, 12, 13, 14, 15, 16, 17, 18, 19. As a result, all phase information of the objects and diffracted light waves is lost 5, 6, 7, 8, 9, 10. But the pixels of most sensors detect only the intensity of electromagnetic waves. The ability to detect light direction beyond optical wavelengths through colour-contrast encoding could enable new applications, for example, in three-dimensional phase-contrast imaging, robotics, virtual reality, tomographic biological imaging and satellite autonomous navigation.Īdvances in materials and semiconductor processes have revolutionized the design and fabrication of micro- and nano-photodetectors. We also demonstrate three-dimensional object imaging and visible light and X-ray phase-contrast imaging by combining pixelated nanocrystal arrays with a colour charge-coupled device. We find that three-dimensional light-field detection and spatial positioning of light sources are possible by modifying nanocrystal arrays with specific orientations. With these multicolour nanocrystal arrays, light rays from specific directions can be converted into pixelated colour outputs with an angular resolution of 0.0018°. Here we present a robust, scalable method based on lithographically patterned perovskite nanocrystal arrays that can be used to determine radiation vectors from X-rays to visible light (0.002–550 nm).
However, current light-field detection techniques either require complex microlens arrays or are limited to the ultraviolet–visible light wavelength ranges 1, 2, 3, 4.
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Light-field detection measures both the intensity of light rays and their precise direction in free space.
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