Compressor and manufacturing method thereof

A compressor comprising:

• a piston that defines a suction space configured to suction a refrigerant gas;
• and
• a cylinder that receives the piston and defines a compression space that is configured to compress, based on reciprocation of the piston in an axial direction, the refrigerant gas therein,
• wherein a plurality of recesses are defined at an inner circumferential surface of the cylinder,
• wherein the plurality of recesses each have a partial spherical shape and have a diameter of 10 micrometers or less,
• wherein the cylinder includes a first gas inlet that fluidly communicates with an internal space of the cylinder at a first opposite side of the gas inlet,
• wherein a plurality of second gas inlets are recessed at an outer circumferential surface of the cylinder and spaced apart from each other in the axial direction is disposed in the axial direction,
• wherein the cylinder further includes a plurality of gas receiving grooves that fluidly communicate with the gas inlets, that are recessed at the inner circumferential surface of the cylinder, and that are spaced apart from each other in the axial direction, and
• wherein the plurality of gas receiving grooves are arranged in a concave curved shape with a radius of curvature less than a radius of curvature of the inner circumferential surface of the cylinder such that the plurality of gas receiving grooves have a depth that changes continuously along a circumferential direction of the cylinder.