Abstract: An optical system affixed to an electronic apparatus is provided, including a first optical module, a second optical module, and a third optical module. The first optical module is configured to adjust the moving direction of a first light from a first moving direction to a second moving direction, wherein the first moving direction is not parallel to the second moving direction. The second optical module is configured to receive the first light moving in the second moving direction. The first light reaches the third optical module via the first optical module and the second optical module in sequence. The third optical module includes a first photoelectric converter configured to transform the first light into a first image signal.

Abstract: A foldable, height-adjustable, and slantable seating device and method of unfolding, adjusting the height, adjusting the slant, and folding the same are disclosed. In one embodiment, a foldable, height-adjustable, and slantable seating device includes: a seat portion; a back portion; a seat frame; a back frame comprising two rear legs; a rear horizontal cross member; two front legs; a front horizontal cross member; two linkage mechanisms; and four leg inserts. In another embodiment, a method of utilizing a seating device that is foldable, slantable, and adjustable in height includes: unfolding; adjusting the height; adjusting the slant; and folding a seating device.