Abstract: A polythiol composition according to exemplary embodiments includes: a polythiol-based compound; and a benzyl halide-based reaction regulator in an amount of 10 ppm to 2,000 ppm based on a weight of the polythiol-based compound. The reaction rate of the polythiol-based compound and an isocyanate-based compound may be controlled through the reaction regulator to inhibit a generation of stria phenomenon.

Abstract: A polythiol composition according to exemplary embodiments includes a first polythiol compound which provides a maximum peak in a high performance liquid chromatography (HPLC) analysis graph obtained at a wavelength of 230 nm, and a second polythiol compound having a molecular weight greater than that of the first polythiol compound and represented by C9H20S6. A ratio of a peak area of the second polythiol compound to a peak area of the first polythiol compound, which are measured through the HPLC analysis graph at the wavelength of 230 nm, is 0.05 to 5.0%.

Abstract: A xylylene diisocyanate composition according to exemplary embodiments includes xylylene diisocyanate (XDI) and chloromethylbenzyl isocyanate (CBI), and may satisfy a predetermined relationship between an acidity and a content of CBI. Thereby, an optical lens having a high transmittance and improved optical uniformity can be manufactured by controlling a polymerization reaction rate.

Abstract: A polythiol composition according to exemplary embodiments includes a main polythiol compound and a sub-compound having a molecular weight higher than that of the main polythiol compound. A peak area (%) at retention times ranging from 34 to 40 minutes in the high performance liquid chromatography (HPLC) analysis graph obtained at a wavelength of 230 nm, which corresponds to the sub-compound, is 2.5% or less. An optical product having improved transmittance and optical properties may be manufactured through fine adjustment of the sub-compound.

Abstract: A polythiol composition according to exemplary embodiments includes at least two different polythiol-based compounds, wherein a peak area (%) of the polythiol compound represented by C8H18S6, which is measured through a high performance liquid chromatographic (HPLC) analysis graph obtained at a wavelength of 230 nm, ranges from 0.90% to 1.30%. By controlling the sub-polythiol compound, an optical product having excellent transmittance and optical properties can be manufactured.

Abstract: A polythiol composition according to exemplary examples includes a tetrafunctional polythiol compound, and a sub-polythiol compound including a compound represented by C13H28S9 and a compound represented by C15H32S10. A ratio of the sub-polythiol compound measured through a high performance liquid chromatography (HPLC) analysis graph is 1% to 5%. By adjusting the content of the sub-polythiol compound, it is possible to manufacture an optical product having excellent transmittance and optical properties.

Abstract: The xylylene diisocyanate composition according to exemplary examples includes xylylene diisocyanate (XDI), and an acidity adjusting agent having a boiling point of 110° C. or higher, wherein the composition has an acidity of more than 100 ppm and 1,000 ppm or less based on a total weight of xylylene diisocyanate (XDI). A polymerization reaction rate is controlled through regulation of the acidity so that an optical lens having high transmittance and improved optical uniformity may be manufactured.

Abstract: A polymerizable composition according to an embodiment includes a first polymerizable compound including isophorone diisocyanate and hexamethylene diisocyanate, and a second polymerizable compound including 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol and pentaerythritol tetrakis(mercaptoacetate). An optical material which is fabricated from the polymerizable composition and has improved optical, mechanical and thermal properties is provided.

Abstract: A long-band (L-band) light source capable of testing the characteristics of optical elements using a feedback loop in a fiber amplifier of an optical communication system.