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 plate (1) and an image scanner (16) disposed to be spaced apart from the light guide plate (1), a light source (2) being disposed at a side of the light guide plate (1). The image acquisition apparatus (8) is integrated into the terminal device (7). The liquid crystal terminal device includes a LCD panel (11), a backlight element (12) and the image acquisition apparatus (8), an image scanner (16) of the image acquisition apparatus (8) being disposed in the backlight element (12). The image acquisition method includes: making at least part of light emitted by the light source (2) enter and propagate inside the light guide plate (1) through TIR, and acquiring an image of an object on the other side of the light guide plate (1) by an image scanner (16). An ultra-thin image acquisition apparatus (8), terminal device (7) and liquid crystal terminal device formed based on a waveguide principle and a multi-pinhole imaging principle significantly reduce the size and thickness of an image acquisition module in the device and greatly facilitate the implementation of mobile devices and embedded devices in which an image acquisition function is required.
