Optical character recognition illumination method and system

A method of illuminating a region of a surface of a substrate, said surface defining a plane, said region comprising a smooth planar field which reflects radiation incident thereon substantially specularly and a marking which reflects non-specularly and/or scatters and/or absorbs a portion of radiation incident thereon, method comprising the steps of:

• providing a first incident beam of radiation which strikes said region at a first angle of incidence, said first angle of incidence being greater than 0 degrees to a normal vector to said plane, said first incident beam having a first reflected beam having a corresponding first angle of reflection from said plane:
• providing a second incident beam of radiation which strikes said region at a second angle of incidence, wherein said field reflects a second reflected beam of radiation at a corresponding second angle of reflection;
• detecting reflected radiation in a detection region of a detector, said detection region positioned at approximately said first angle of reflection from said surface, such that said second reflected beam does not strike said detection region;
• and
• determining which of said first incident beam and said second incident beam provides the best contrast between said field and said marking.

A method of illuminating a region of a surface of a substrate, said surface defining a plane, said region comprising a smooth planar field which reflects radiation incident thereon substantially specularly and a marking which reflects non-specularly and/or scatters and/or absorbs a portion of radiation incident thereon, said method comprising the steps of:

• providing a first incident beam of radition which strikes said region at a first angle of incidence, said first angle of incidence being greater than 0 degrees to a normal vector to said plane, said first incident beam having a first reflected beam having a corresponding first angle of reflection from said plane;
• providing a second incident beam of radiation which strikes said region at a second angle of incidence, wherein said field reflects a second reflected beam of radiation at a corresponding second angle of reflection;
• providing a third incident beam of radiation which strikes said region at a third angle of incidence, wherein said field reflects a third reflected beam of radiation at a corresponding third angle of reflection;
• detecting reflected radiation in a detecting region of detector, said detection region positioned at approximately said first angle of reflection from said surface, such that said second reflected beam and said third reflected beam do not strike said detection region;
• and
• determining which of said first incident beam, said second incident beam, and said third incident beam provides the best contrast between said field and said marking.

An apparatus for illuminating a region of a surface of a substrate, said surface defining a plane, said region comprising a smooth planar field which reflects radiation incident thereon substantially specularly and a marking which reflects non-specularly and/or scatters and/or absorbs a portion of radiation incident thereon, said apparatus comprising:

• a first radiation source assembly, said first radiation source assembly emitting a first incident beam of radiation which strikes said region at a first angle of incidence, said first angle of incidence being greater than 0 degrees to a normal vector to said plane, said first incident beam having a first reflected beam having a corresponding first angle of reflection from said plane;
• a second radiation source assembly, said second radiation source assembly emitting a second incident beam of radiation which strikes said region at a second angle of incidence, wherein said field reflects a second reflected beam of radiation at a corresponding second angle of reflection;
• a detector, said detector positioned at approximately said first angle of reflection from said surface such that said first reflected beam strikes a detection region of said detector and such that said second reflected beam does not strike said detection region;
• and
• a selector, wherein said selector determines which of said first incident beam and said second incident beam provides the best contrast between said field and said marking.

An apparatus for illuminating a region of a surface of a substrate, said surface defining a plane, said region comprising a smooth planar field which reflects radiation incident thereon substantially specularly an a marking which reflects non-specularly and/or scatters and/or absorbs a portion of radiation incident thereon, said apparatus comprising:

• a first radiation source assembly, said first radiation source assembly emitting a first incident beam of radiation which strikes said region at a first angle of incidence, said first angle of incidence being greater than 0 degrees of a normal vector to said plane, said first incident beam having a first reflected beam having a corresponding first angle of reflection from said plane;
• a second radiation source assembly, said second radiation source assembly emitting a second incident beam of radiation which strikes said region at a second angle of incidence, wherein said field reflects a second reflected beam of radiation at a corresponding second angle of reflection;
• a third radiation source assembly, said third radiation source assembly emitting a third incident beam of radiation which strikes said region at a third angle of incidence, wherein said field reflects a third reflected beam of radiation at a corresponding third angle of reflection;
• and
• a detector, said detector positioned a approximately said first angle of reflection from said surface such that said first reflected beam strikes a detection region of said detector and such that said second and third reflected beams do not strike said detection region;
• and
• a selector, wherein said selector determines which of said first incident beam, said second incident beam, and said third incident beam provides the best contrast between said field and said marking.