Reflectance method for evaluating the surface characteristics of opaque materials

A method for determining whether a planar surface of an opaque material has a plurality of prismatic irregularities thereon, the method comprising:

• directing light at an incident angle with respect to the planar surface of the opaque material;
• graphically plotting a measured intensity of the light reflected from the opaque material at a plurality of angles of reflection;
• determining that the planar surface of the opaque material has a plurality of prismatic irregularities thereon when the graphical plot of the measured intensity of the light reflected from the opaque material for the plurality of angles of reflection has a pluralities of peaks, wherein:
• one of said plurality of peaks occurs at a first angle of reflection equal to 180 degrees less the angle of incidence;
• the other of said plurality of peaks occur at respective angles of reflection equal to 180 degrees less the angle of incidence less twice an angle that a surface of each respective prismatic irregularity makes with the planar surface of the opaque material;
• and the measured intensity of the light reflected at all other angles of the plurality of angles of reflection are substantially less than that of said plurality of peaks.

A method for determining whether a planar surface of an opaque material has a prismatic irregularity thereon, the method comprising:

• directing light at an incident angle with respect to the planar surface of the opaque material;
• graphically plotting a measured intensity of the light reflected from the opaque material at a plurality of angles of reflection;
• determining that the planar surface of the opaque material has a prismatic irregularity thereon when the graphical plot of the measured intensity of the light reflected for the plurality of angles of reflection has a first and a second peak, wherein:
• the first peak occurs at a first angle of reflection equal to 180 degrees less the angle of incidence;
• the second peak occurs at a second angle of reflection equal to 180 degrees less the angle of incidence less twice an angle that a surface of the prismatic irregularity makes with the planar surface of the opaque material;
• and the measured intensity of the light reflected at all other angles of the plurality of angles of reflection are substantially less than that of the first and second peaks.

A method for determining whether a planar surface of an opaque material has a prismatic irregularity thereon using a UV reflectometer, the method comprising:

• directing ultraviolet light at an incident angle with respect to the planar surface of the opaque material;
• measuring the intensity of the UV light reflected from the opaque material at a plurality of angles of reflection using a UV reflectometer;
• graphically plotting the intensity of the UV light reflected from the opaque material by the UV reflectometer at each angle of reflection;
• determining that the planar surface of the opaque material has a prismatic irregularity thereon when the graphical plot has a first and a second peak, wherein:
• the first peak occurs at a first angle of reflection equal to 180 degrees less the angle of incidence;
• the second peak occurs at a second angle of reflection equal to 180 degrees less the angle of incidence less twice an angle that a surface of the prismatic irregularity makes with the planar surface of the opaque material;
• and the measured intensity of the UV light reflected at all other angles of the plurality of angles of reflection is substantially less than that of the first and second angles.

A method for determining whether a planar surface of an opaque material has a hemispherical irregularity thereon, the method comprising:

• directing light from a light source at an incident angle with respect to the planar surface of the opaque material;
• graphically plotting a measured intensity of the light reflected from the opaque material at a plurality of angles of reflection;
• determining that the planar surface of the opaque material has a hemispherical irregularity thereon when the graphical plot of the measured intensity of the light reflected from the opaque material for the plurality of angles of reflection has a first and a second peak, wherein:
• the first peak occurs at about 180 degrees less the angle of incidence;
• the second peak occurs at about the angle of incidence;
• and the measured intensity of the light reflected at all other angles of the plurality of angles of reflection are non-zero.

A method for determining whether a planar surface of an opaque material has a hemispherical irregularity thereon using an ultraviolet (UV) reflectometer, the method comprising:

• directing UV light at an incident angle with respect to the planar surface of the opaque material;
• measuring the intensity of the UV light reflected from the opaque material at a plurality of angles of reflection using a UV reflectometer;
• graphically plotting the intensity of the UV light reflected from the opaque material by the UV reflectometer at each angle of reflection;
• determining that the planar surface of the opaque material has a hemispherical irregularity thereon when the graphical plot of the measured intensity of the UV light reflected from the opaque material for the plurality of angles of reflection has a first and a second peak, wherein:
• the first peak occurs at about 180 degrees less the angle of incidence;
• the second peak occurs at about the angle of incidence;
• and the measured intensity of the light reflected at all other angles of the plurality of angles of reflection are non-zero.