[1] Settles G S. Toepler's schlieren technique[M]. ∥Schlieren and Shadowgraph Techniques. Experimental Fluid Mechanics. Berlin, Heidelberg: Springer, 39-75(2001).

[2] Kline S J. Flow visualization by wolfgang merzkirk[J]. American Scientist, 63, 241(1975).

[3] Westerweel J. Fundamentals of digital particle image velocimetry[J]. Measurement Science and Technology, 8, 1379-1392(1999). http://www.researchgate.net/publication/231118221_Fundamentals_of_Digital_Particle_Image_Velocimetry

[4] Knudsen P J T, Svender J. Doppler radar velocity measurements for wound ballistics experiments[J]. International Journal of Legal Medicine, 107, 1-6(1994).

[5] Richard H, Raffel M. Principle and applications of the background oriented schlieren (BOS) method[J]. Measurement Science and Technology, 12, 1576-1585(2001). http://www.ingentaconnect.com/content/iop/mst/2001/00000012/00000009/art00325

[6] Hargather M J, Settles G S. Natural-background-oriented schlieren imaging[J]. Experiments in Fluids, 48, 59-68(2010). http://dx.doi.org/10.1007/s00348-009-0709-3

[7] Raffel M, Heineck J T, Schairer E T et al. Background-oriented schlieren imaging for full-scale and in-flight testing[J]. Journal of the American Helicopter Society, 59, 1-19(2013). http://www.ingentaconnect.com/content/ahs/jahs/2014/00000059/00000001/art00002

[8] Schairer E T, Kushner L K, Heineck J T[2019-11-20]. Measurements of tip vortices from a full-scale UH-60A rotor by retro-reflective background oriented schlieren and stereo photogrammetry [2019-11-20].https:∥ntrs.nasa.gov/api/citations/20130013745/down.

[9] Smith N T, Heineck J T, Schairer E T. Optical flow for flight and wind tunnel background oriented schlieren imaging. [C]∥55th AIAA Aerospace Sciences Meeting, January 9-13, 2017, Grapevine, Texas. Reston. Virginia: AIAA(2017).

[10] Heineck J T, Banks D, Schairer E T et al. Background oriented schlieren (BOS) of a supersonic aircraft in flight. [C]∥AIAA Flight Testing Conference, June 13-17, 2016, Washington, D.C. Reston, Virginia: AIAA(2016).

[11] Hill M A, Haering E A. Flow visualization of aircraft in flight by means of background oriented schlieren using celestial objects. [C]∥33rd AIAA Aerodynamic Measurement Technology and Ground Testing Conference, June, 5-9, 2017, Denver, Colorado. Reston. Virginia: AIAA(2017).

[12] Haering A. -03-21[2019-12-03]. http:∥www.google.co.in/patents/US9599497B1.(2017).

[13] Hill M A, Haering E A. Ground-to-air flow visualization using solar calcium-K line background-oriented schlieren[J]. Experiments in Fluids, 58, 1-12(2016). http://dx.doi.org/10.1007/s00348-016-2285-7

[15] Zhang Y, Su Y, Gao P et al. Visual monitoring method for atmospheric disturbance of moving objects[J]. Infrared and Laser Engineering, 49, 146-154(2020).

[16] Wu Y C. Theories and application research of computational flow imaging[D]. Nanjing: Nanjing University of Science and Technology, 27-31(2003).

[17] Lu J A, Shang T, Xie J et al[M]. Matlab solution of partial differential equation, 134-141(2001).