An optical system, comprising: a light source adapted to emit a light beam; and an optical lens (100; 100b; 100c) disposed on a transmission path of the light beam, the optical lens (100; 100b; 100c) comprising: a plurality of lenticular lens units extending along a same direction, the lenticular lens units being disposed side by side along a direction perpendicular to the extension direction thereof, wherein each of the lenticular lens units has a height relative to a bottom surface of the optical lens (100; 100b; 100c), any adjacent two of the lenticular lens units have a height difference D therebetween, and the height difference is not less than a minimum height difference D defined by an equation D = 2 ln 2 πn λ 2 Δ λ, wherein n represents a refractive index of the optical lens (100; 100b; 100c), λ represents a central wavelength of the light beam, and Δλ represents a spectral bandwidth of the light beam; wherein the lenticular lens units of the optical lens comprise a plurality of first lenticular lens units and a plurality of second lenticular lens units, the first lenticular lens units and the second lenticular lens units are alternately arranged, the first lenticular lens units have a same first height and the second lenticular lens units have different heights from each other. a light source adapted to emit a light beam; and an optical lens (100; 100b; 100c) disposed on a transmission path of the light beam, the optical lens (100; 100b; 100c) comprising: a plurality of lenticular lens units extending along a same direction, the lenticular lens units being disposed side by side along a direction perpendicular to the extension direction thereof, wherein each of the lenticular lens units has a height relative to a bottom surface of the optical lens (100; 100b; 100c), any adjacent two of the lenticular lens units have a height difference D therebetween, and the height difference is not less than a minimum height difference D defined by an equation D = 2 ln 2 πn λ 2 Δ λ, wherein n represents a refractive index of the optical lens (100; 100b; 100c), λ represents a central wavelength of the light beam, and Δλ represents a spectral bandwidth of the light beam; wherein the lenticular lens units of the optical lens comprise a plurality of first lenticular lens units and a plurality of second lenticular lens units, the first lenticular lens units and the second lenticular lens units are alternately arranged, the first lenticular lens units have a same first height and the second lenticular lens units have different heights from each other. a plurality of lenticular lens units extending along a same direction, the lenticular lens units being disposed side by side along a direction perpendicular to the extension direction thereof, wherein each of the lenticular lens units has a height relative to a bottom surface of the optical lens (100; 100b; 100c), any adjacent two of the lenticular lens units have a height difference D therebetween, and the height difference is not less than a minimum height difference D defined by an equation D = 2 ln 2 πn λ 2 Δ λ, wherein n represents a refractive index of the optical lens (100; 100b; 100c), λ represents a central wavelength of the light beam, and Δλ represents a spectral bandwidth of the light beam; wherein the lenticular lens units of the optical lens comprise a plurality of first lenticular lens units and a plurality of second lenticular lens units, the first lenticular lens units and the second lenticular lens units are alternately arranged, the first lenticular lens units have a same first height and the second lenticular lens units have different heights from each other.