[1] [1] CHEN J W, FU S F, ZHANG D K, et al. Producing grating with variable spacing [J]. Chinese Journal of Lasers, 1986, 13(5): 291-294.

[2] [2] WANG K N, ZHENG J H, LU F Y, et al. Varied-line-spacing switchable holographic grating using polymer-dispersed liquid crystal [J]. Applied Optics, 2016, 55(18): 4952-4957.

[3] [3] XIE Y J, XU X D, HONG Y L, et al. Fabrication of varied-line-spacing grating by elastic medium [J]. Optics Express, 2004, 12(17): 3894-3899.

[4] [4] STROCOV V N, SCHMITT T, FLECHSIG U, et al. Numerical optimization of spherical variable-line-spacing grating X-ray spectrometers [J]. Journal of Synchrotron Radiation, 2011, 18(2): 134-142.

[5] [5] LOU J, FU S J, XU X D, et al. Design and fabrication of holographic variable line-spacing gratings for position sensor [J]. Acta Physica Sinica, 2006, 55(12): 6405-6409.

[6] [6] KANG R D, LIU J A, XUE G L, et al. Curved multiplexing computer-generated hologram for 3D holographic display [J]. Optics Express, 2019, 27(10): 14369-14380.

[7] [7] SHEN T, CAI Z X, LIU Y R, et al. Switchable pupil expansion propagation using orthogonal superposition varied-line-spacing H-PDLC gratings in a holographic waveguide system [J]. Applied Optics, 2019, 58(24): 6622-6628.

[8] [8] BUNNING T J, NATARAJAN L V, TONDIGLIA V P, et al. Holographic polymer-dispersed liquid crystals (H-PDLCs) [J]. Annual Review of Materials Science, 2000, 30(1): 83-115.

[9] [9] LIU Y J, SUN X W. Holographic polymer-dispersed liquid crystals: materials, formation, and applications [J].Advances in OptoElectronics, 2008, 2008: 684349.

[10] [10] BRONNIKOV S, KOSTROMIN S, ZUEV V. Polymer-dispersed liquid crystals: progress in preparation, investigation, and application [J].Journal of Macromolecular Science-Physics, 2013, 52(12): 1718-1735.

[13] [13] YIN K, LEE Y H, HE Z Q, et al. Stretchable, flexible, rollable, and adherable polarization volume grating film [J]. Optics Express, 2019, 27(4): 5814-5823.