An image acquisition apparatus, a terminal device, a liquid crystal terminal device, and an image acquisition method are provided. The image acquisition apparatus (8) includes a light guide panel (1) and an image device (16) disposed at an interval from said light guide plate (1), a light source (2) being disposed on one side of the light guide panel (1)； the image acquisition apparatus (8) is integrated into the terminal device (7)； the liquid crystal terminal device comprises a liquid crystal panel (11), a backlight module (12) and the image acquisition apparatus (8), the image acquisition device (16) of the image acquisition apparatus (8) being arranged in the backlight module (12)； the image acquisition method is: making at least some of light emitted by the light source (2) into the light guide panel (1) have total reflection and transmission, and by means of the image acquisition device (16), acquiring an image of a detected object on the other side of the light guide panel (1). Forming an ultra-thin image acquisition apparatus (8), terminal device (7) and liquid crystal terminal device based on waveguide principles and porous imaging principles can dramatically reduce the size and thickness of an image acquisition module within a device, greatly facilitating the implementation of mobile devices and in-cell devices requiring an image acquisition function.
