Patent ID: 7842740

Claim:
A non-birefringent optical resin material containing a composite constituent system of constituent number z not smaller than 3 under definition of constituent number, such that monomer-element number x (x≧2) of a copolymer is included in constituent number z, wherein said composite constituent system consists of either only a copolymerization system(s) of monomer-element number x not smaller than 3 or both a copolymer of monomer-element number x not smaller than 2 and at least one low molecular-weight organic compound which has an anisotropic polarizability and is capable of being orientated in a polymer; a combination of constituents composing said composite constituent system are set so that at least one of respective signs of characteristic orientation birefringence of respective homopolymers corresponding to respective monomers providing respective components of said copolymer, and a common sign of orientation birefringence shown by said low molecular-weight organic compound in said respective homopolymers is different from the other signs of orientation birefringence, and further so that at least one of respective signs of photoelasticity birefringence of said respective homopolymers and a common sign of photoelasticity birefringence shown by said low molecular-weight organic compound in said respective homopolymers is different from the other signs of photoelasticity birefringence; and a constituent ratio of constituents composing said composite constituent system are set so that said non-birefringent optical resin material has orientation birefringence and photoelasticity birefringence both of which are respectively deadened due to different-sign relations about said orientation birefringence and said photoelasticity birefringence, thereby rendering said characteristic orientation birefringence provided with an absolute value not greater then 6.7×10 −2 and also rendering said photoelasticity birefringence provided with an absolute value not greater than 5.0×10 −11 (Pa −1 ).