Fig. 1. Phase imaging principle based on four-wave lateral shearing interference using randomly coded hybrid grating (REHG)

Fig. 2. Least square wavefront reconstruction from four-wave lateral shearing interferogram

Fig. 3. Measurement results of optical aberrations using FIS4 for two different doublet lenses. (a)-(c) Interferogram, aberration measurement results from FIS4, and aberration measurement results from the ZYGO GPI interferometer, respectively, for a doublet lens with a 50 mm focal length; (d)-(f) Interferogram, aberration measurement results from FIS4, and aberration measurement results from the ZYGO GPI interferometer, respectively, for a doublet lens with a 90 mm focal length

Fig. 4. (a) Inverted mode of living cell microscope on C-type inverted alloy table; (b) Imaging light path of the microscope; (c) Upright mode of the microscope

Fig. 5. Observation of red blood cell dynamics using FIS4 microscope. (a) Dynamic imaging of a red blood cell in plasma over 15 seconds; (b) An enlarged view of the dashed box area in (a); (c) Cell membrane fluctuations calculated based on the standard deviation (reprinted according to reference [16], CC BY 4.0)

Fig. 6. Changes in the state of live ESC cells during the autophagy process, observed at 20× magnification at 0, 4, 8 hours

Fig. 7. Localization of nanoparticles based on intensity and phase imaging. (a) Optical path diagram; (b) Intensity and phase images of 100 nm diameter nanoparticles at focus (z=0) and slight defocus (z=±250 nm); (c) Experimental data points and simulation curves for intensity (black) and phase (red) of 100 nm diameter nanoparticles as a function of axial sample displacement (reprinted according to reference [35], CC BY 4.0)

Fig. 8. (a) Schematic of the four-wave shearing white light profiler; (b) Portable FIS4 white light profiler

Fig. 9. (a) Local contour map and 3D map of the protruding ring on the surface of the sample detected by FIS4 white light profiler; (b) Contour map and 3D map of standard lines on fused quartz calibration plate surface

Fig. 10. (a) Contour map and surface roughness of optical elements detected by FIS4 white light profiler; (b) Contour map and surface microstructure of block gauge

Fig. 11. Schematic diagram of FIS4 for laser wavefront sensing and analysis

Fig. 12. Laser wavefront sensing using FIS4. (a) Measurement results of large aperture wavefront with a wavelength of 351 nm and an aperture of 100 mm; (b) Measurement results of large aperture wavefront with a 1053 nm near-infrared wavelength and an aperture of 100 mm

Fig. 13. Calibration analysis of laser wavefront sensing. (a) Measurement result of a fused quartz ring calibration plate by a step meter; (b) Test results of the fused quartz ring calibration plate using FIS4 laser interferometer

Fig. 14. Schematic diagram of FIS4 laser interferometer for high-speed flow field analysis in wind tunnel

Fig. 15. FIS4 wavefront sensor for adaptive optical system

Fig. 16. (a) Input wavefront PV using a spatial light modulator =0.49 μm; (b) Detected PV by FIS4 interferometric wavefront sensor =0.498 μm

Fig. 17. (a) Input wavefront PV on the spatial light modulator =0.98 μm; (b) Detected PV by FIS4 interferometric wavefront sensor = 0.966 μm

Fig. 18. (a) Inverted input wavefront PV on the spatial light modulator =2.46 μm; (b) Detected PV by FIS4 interferometric wavefront sensor =2.434 μm

Table 1. Comparison between various quantitative phase imaging techniques