Patent ID: 8351116

Claim:
An optical component including an input surface which receives light beams of at least two wavelengths, and an output surface which outputs the light beams after changing a phase of the received light beam, comprising: an optical medium body which includes at least two optical mediums arranged side by side between said input surface and said output surface, said optical medium body including: a first optical medium portion which outputs each of said light beams of at least two wavelengths after changing a phase thereof according to the wavelength, a second optical medium portion which outputs each of said light beams of at least two wavelengths after changing a phase thereof according to the wavelength so that difference between a phase of the light beam outputted from said first optical medium portion and a phase of the light beam outputted from said second optical medium portion is approximately constant, wherein said first optical medium portion is composed of at least one optical medium layer, said second optical medium portion is composed of at least one optical medium layer, the following three formulas are applied to said first optical medium portion and said second optical medium portion, ∑ i ⁢ ⁢ t 1 ⁢ i × n 1 ⁡ ( i , 1 ) - ∑ j ⁢ ⁢ t 2 ⁢ j × n 2 ⁡ ( j , 1 ) = C ⁢ ⁢ 1 ⁢ λ 1 ∑ i ⁢ ⁢ t 1 ⁢ i × n 1 ⁡ ( i , 2 ) - ∑ j ⁢ ⁢ t 2 ⁢ j × n 2 ⁡ ( j , 2 ) = C ⁢ ⁢ 2 ⁢ λ 2  C ⁢ ⁢ 1 - C ⁢ ⁢ 2  < 0.02 a thickness of i th layer of said first optical medium portion is the thickness t 1i , a refractive index to the light beam of the wavelength λ 1 is the refractive index n 1 (i,1), a refractive index to the light beam of the wavelength λ 2 is the refractive index n 1 (i,2), a thickness of j th layer of said second optical medium portion is the thickness t 1j , a refractive index to the light beam of the wavelength λ 1 is the refractive index n 2 (j,1), a refractive index to the light beam of the wavelength λ 2 is the refractive index n 2 (j,2), C1 and C2 are constants which are not related to wavelength; and wherein the thickness and index of refraction of the first and second optical medium portions are such that a phase delay for two different wavelengths λ 1 and λ 2 are substantially the same.