One or more trays for use in distillation columns and methods of manufacture of such trays. The trays include a plate having a plurality of through holes that extend between a first surface of the plate and a second surface of the plate. The plurality of through holes include a first set of through holes each having substantially a first diameter and a second set of through holes each having substantially a second diameter that is different from the first diameter. The trays also include a weir coupled to the plate and extending from the first surface. The weir is positioned between the first set of through holes and the second set of through holes.

The illustrative embodiment of the present invention uses a tangible three-dimensional structure as a fiducial mark, which structure is, at least partially, tolerant of dimensional variations in the article. The illustrative embodiment uses three such tangible three-dimensional structures: (1) a portion of a tangible conical surface, (2) a portion of a tangible spheroidal surface, and (3) a portion of a tangible pyramidal surface.

The illustrative embodiment of the present invention uses a tangible three-dimensional structure as a fiducial mark, which structure is, at least partially, tolerant of dimensional variations in the article. The illustrative embodiment uses three such tangible three-dimensional structures: (1) a portion of a tangible conical surface, (2) a portion of a tangible spheroidal surface, and (3) a portion of a tangible pyramidal surface.

The illustrative embodiment of the present invention uses a tangible three-dimensional structure as a fiducial mark, which structure is, at least partially, tolerant of dimensional variations in the article. The illustrative embodiment uses three such tangible three-dimensional structures: (1) a portion of a tangible conical surface, (2) a portion of a tangible spheroidal surface, and (3) a portion of a tangible pyramidal surface.

The illustrative embodiment of the present invention uses a tangible three-dimensional structure as a fiducial mark, which structure is, at least partially, tolerant of dimensional variations in the article. The illustrative embodiment uses three such tangible three-dimensional structures: (1) a portion of a tangible conical surface, (2) a portion of a tangible spheroidal surface, and (3) a portion of a tangible pyramidal surface.

The illustrative embodiment of the present invention uses a tangible three-dimensional structure as a fiducial mark, which structure is, at least partially, tolerant of dimensional variations in the article. The illustrative embodiment uses three such tangible three-dimensional structures: (1) a portion of a tangible conical surface, (2) a portion of a tangible spheroidal surface, and (3) a portion of a tangible pyramidal surface.

The illustrative embodiment of the present invention uses a tangible three-dimensional structure as a fiducial mark, which structure is, at least partially, tolerant of dimensional variations in the article. The illustrative embodiment uses three such tangible three-dimensional structures: (1) a portion of a tangible conical surface, (2) a portion of a tangible spheroidal surface, and (3) a portion of a tangible pyramidal surface.

The invention is directed to a reusable mold for making a contact lens and the reusable mold has at least one of the mold halves is made from an oxide glass having a Knoop Hardness less than HK 350. The invention is also directed to a method for making an optical part by single point diamond turning an oxide glass having a Knoop Hardness HK less than 350.

The illustrative embodiment of the present invention uses a tangible three-dimensional structure as a fiducial mark, which structure is, at least partially, tolerant of dimensional variations in the article. The illustrative embodiment uses three such tangible three-dimensional structures: (1) a portion of a tangible conical surface, (2) a portion of a tangible spheroidal surface, and (3) a portion of a tangible pyramidal surface.

The invention is directed to a reusable mold for making a contact lens and the reusable mold has at least one of the mold halves is made from an oxide glass having a Knoop Hardness less than HK 350. The invention is also directed to a method for making an optical part by single point diamond turning an oxide glass having a Knoop Hardness HK less than 350.