Abstract: A photocurable composition, wherein a small amount of an alicyclic skeleton-containing mono(meth) acrylate is incorporated in a combination of an alicyclic skeleton-containing bis(meth)acrylate and a mercapto compound, a cured product obtained by the copolymerization thereof, and a process for producing the cured product.

Abstract: A photocurable composition, wherein a small amount of an alicyclic skeleton-containing mono(meth) acrylate is incorporated in a combination of an alicyclic skeleton-containing bis(meth)acrylate and a mercapto compound, a cured product obtained by the copolymerization thereof, and a process for producing the cured product.

Abstract: An optical device is useful as a microlens array or a grating lens, which comprises microlens portions each having a light transmittance of not less than 80% within a visible light range, and produced by subjecting a photo-curable monomer composition to two-stage light-irradiation comprising a partial irradiation and a whole irradiation.

Abstract: A cured resin for high-fraction lenses is disclosed, which is obtained by polymerizing a composition comprising (A) from 70 to 99 parts by weight of a sulfur-containing aromatic (meth)acrylate represented by formula (I): ##STR1## wherein R.sup.1 represents a hydrogen atom or a methyl group; R.sup.2 represents an alkylene group; Ar represents an arylene group, an arylene group substituted with a halogen atom except a fluorine atom, an aralkylene group, or an aralkylene group substituted with a halogen atom except a fluorine atom; X represents --O-- or --S--; Y represents --S-- or --SO.sub.2 -- when X is --O--, or Y represents --S--, --SO.sub.

Abstract: A sulfur-containing acryl oligomer composition represented by formula (I): ##STR1## wherein R.sub.1 represents a hydrogen atom or a methyl group; R.sub.2 and R.sub.3 each represents an alkylene group having from 1 to 12 carbon atoms; R.sub.4 represents an alkylene group having from 1 to 12 carbon atoms, an oxydialkylene group having from 2 to 12 carbon atoms, or an aralkylene group having from 6 to 20 carbon atoms; X represents a chlorine, bromine or iodine atom; m represents 0 or an integer of from 1 to 4; and n represents an average degree of oligomerization of 10 or smaller.The oligomer composition provides on polymerization a cured product having a refractive indices of 1.60 or higher, excellent transparency, and optical uniformity and is therefore useful as a material for plastic lenses.