An apparatus for optical testing of a sample of optical material, the apparatus comprising: (a) an assembly comprising: (i) an optically transparent general-cylinder having an interior partially filled with a bulk material portion from an interior surface of said general-cylinder toward a center axis of said general-cylinder , and said interior having a hollow portion extending from an opposite interior surface of said general cylinder and including said axis, said hollow sized to receive at least a core area of the sample of optical material, (ii) a receptacle including said hollow , said receptacle sized to receive at least a portion of the sample of optical material, and said receptacle sealed for receiving a quantity of fluid , such that said fluid surrounds and is in contact with at least said core area, and is in contact with said general-cylinder and at least a portion of said bulk , and (b) an optical arrangement: (i) aligned with said axis, (ii) including an optical source providing an optical light beam normal to a circumferential surface area at a first side of said general-cylinder , and (iii) including an optical detector accepting an output signal , said output signal from said optical light beam impinging on said core area and transmitted through or reflected from the sample , said optical detector normal to a circumferential surface area of said general-cylinder . (a) an assembly comprising: (i) an optically transparent general-cylinder having an interior partially filled with a bulk material portion from an interior surface of said general-cylinder toward a center axis of said general-cylinder , and said interior having a hollow portion extending from an opposite interior surface of said general cylinder and including said axis, said hollow sized to receive at least a core area of the sample of optical material, (ii) a receptacle including said hollow , said receptacle sized to receive at least a portion of the sample of optical material, and said receptacle sealed for receiving a quantity of fluid , such that said fluid surrounds and is in contact with at least said core area, and is in contact with said general-cylinder and at least a portion of said bulk , and (i) an optically transparent general-cylinder having an interior partially filled with a bulk material portion from an interior surface of said general-cylinder toward a center axis of said general-cylinder , and said interior having a hollow portion extending from an opposite interior surface of said general cylinder and including said axis, said hollow sized to receive at least a core area of the sample of optical material, (ii) a receptacle including said hollow , said receptacle sized to receive at least a portion of the sample of optical material, and said receptacle sealed for receiving a quantity of fluid , such that said fluid surrounds and is in contact with at least said core area, and is in contact with said general-cylinder and at least a portion of said bulk , and (b) an optical arrangement: (i) aligned with said axis, (ii) including an optical source providing an optical light beam normal to a circumferential surface area at a first side of said general-cylinder , and (iii) including an optical detector accepting an output signal , said output signal from said optical light beam impinging on said core area and transmitted through or reflected from the sample , said optical detector normal to a circumferential surface area of said general-cylinder . (i) aligned with said axis, (ii) including an optical source providing an optical light beam normal to a circumferential surface area at a first side of said general-cylinder , and (iii) including an optical detector accepting an output signal , said output signal from said optical light beam impinging on said core area and transmitted through or reflected from the sample , said optical detector normal to a circumferential surface area of said general-cylinder . <EOS>