Digital self-aligned focusing schlieren

In this Letter, a digital self-aligned focusing schlieren (D-SAFS) system is introduced. This system uses a digital transparent micro liquid crystal display (μLCD), in combination with a linear polarizer, to act on the linear polarization state of light transmitted in both the forward and reverse directions, essentially acting as both the source and cutoff grids. The use of the μLCD display allows for on-the-fly changes to the cutoff pattern type, spatial frequency, and orientation. This eliminates the need to physically access the source/cutoff grid in order to optimize the instrument's sensitivity, which is necessary with a conventional self-aligned focusing schlieren (SAFS) system.