Schlieren photography normally uses a background light source grid or mirror system to send light through a sample area and a second grid or a knife edge at the camera to block nondeflected light. We describe a new technique that uses the inactive areas between CCD or CMOS sensor pixels as the second grid, so only a background grid is needed. This simplifies the setup and lowers the cost of the system.
Robert B. Teese,
Matthew M. Waters,
"Inexpensive schlieren video technique using sensor dead space as a grid," Optical Engineering 43(11), (1 November 2004). https://doi.org/10.1117/1.1804546