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: An air stone suitable for use in aerating water in an aquarium is formed of a body of porous material permeable to air. Included within the body is a central chamber having an inlet port for receiving a connector, the chamber extending beyond the port to form a plenum for distribution of air throughout the air stone. In an embodiment of the air stone constructed with a circular cylindrical configuration, the plenum is enclosed by a cylindrical wall of porous material and closed off by an end wall of porous material. The cylindrical wall has uniform thickness equal to the thickness of the end wall. The connector includes a nipple extending into the chamber to make a press fit for securing the stone to the connector. A similar nipple directed in the opposite direction secures the connector to an air-supply tube.