Abstract: An optical structure is provided. The optical structure includes a substrate and a light-emitting element disposed on the substrate. The optical structure also includes a cap disposed on the substrate and covering the light-emitting element. The cap has a top portion and a sidewall connected to the top portion. The optical structure further includes a first micro-structure disposed on a first side of the top portion facing the light-emitting element. The first micro-structure is periodically arranged.

Abstract: A method and a device implementing the method for making coffee are provided herein. The method and the related device use pressurized air as a media for pushing water under uniform pressure to flow through the coffee cake such that high-quality crema will be formed. The method basically contains the following steps. First, a water tank partially filled with hot water is provided. Then, high pressure air is filled and maintained within the water tank without releasing. A check valve leading to the coffee cake is then opened and the hot water is pushed by the high-pressure air to flow through the check valve and coffee cake. The temperature of the hot water is between 80˜100° C., and the amount of water is between one to two thirds of the volume of the water tank. The pressure level of the high-pressure air is between 6˜10 atm.