Transmission Optical System of Determined Residual Reflection Color, System for Manufacturing Thereof and Apparatus for Evaluating a Difference in Residual Reflection Color

An apparatus for evaluating a difference in residual reflection color between a first transmission optical system and a second transmission optical system, wherein each of the first and second transmission optical system comprises an optical base element having a first face adapted to receive incident optical lights and a second face through which transmitted optical lights exit, each of the first and second transmission optical system comprising an interferential coating on the first face providing the first, and respectively second, transmission optical system with a mean visible light reflection factor Rv that is less than or equal to 2.5%, each of the first and second transmission optical system presenting by reflection on said first face a residual reflection color, said apparatus comprising:

• an identification system adapted to read or determine a residual color identifier of the first transmission optical system, and respectively, of the second transmission optical system;
• the residual color identifier of the first transmission optical system being based in part on colorimetric coordinates of the first transmission optical system in CIELab color space and in part on colorimetric coordinates of the first transmission optical system in CIELUV color space and the residual color identifier of the second transmission optical system being based in part on colorimetric coordinates of the second transmission optical system in CIELab color space and in part on colorimetric coordinates of the second transmission optical system in CIELUV color space;
• and
• a pairing unit adapted to determine a difference in residual reflection color between the first and second transmission optical systems, said difference in residual reflection color being based on a comparison between the residual color identifier of the first transmission optical system and the residual color identifier of the second transmission optical system.

A system for manufacturing a transmission optical system comprising an optical base element and an interferential coating on at least one face of the base element, the interferential coating providing the transmission optical system with a mean visible light reflection factor Rv that is less than or equal to 2.5%, said transmission optical system presenting by reflection on said face a predetermined residual reflection color, wherein the system comprises:

• a computer system comprising an optical design software adapted to:
• a) define a theoretical interferential coating comprising a stack of dielectric layers, said theoretical interferential coating having a mean visible light reflection factor Rv that is less than or equal to 2.5%;
• b) calculate a nominal hue angle in the CIELab color space and a nominal residual color identifier based in part on colorimetric coordinates in CIELab color space and in part on colorimetric coordinates in CIELUV color space of the theoretical interferential coating;
• c) define ranges of manufacturing variations in the stack of dielectric layers so as to form a collection of predictable interferential coatings;
• d) for each predictable interferential coating of the collection, calculate a predictable hue angle in the CIELab color space and a predictable residual color identifier based in part on colorimetric coordinates in CIELab color space and in part on colorimetric coordinates in CIELUV color space;
• e) for each predictable interferential coating of the collection, calculate a difference in residual reflection color between the predictable interferential coating and the theoretical interferential coating based on the predictable residual reflection color identifier of the predictable interferential coating and on the nominal residual color identifier of the theoretical interferential coating;
• f) use a pairing database storing predetermined multi-dimension pairing ranges as a function of predetermined hue angles to validate or invalidate if each predictable interferential coating of the collection presents with the theoretical interferential coating a difference in residual reflection color inside a multi-dimension pairing range associated to the nominal residual color identifier of the theoretical interferential coating, said multi-dimension pairing range comprising a pairing range of a hue deviation parameter associated to the nominal hue angle and a two-dimension pairing range of lightness difference and saturation difference associated to the nominal hue angle and to said nominal residual color identifier;
• a validation unit adapted to adjust the stack of dielectric layers of the theoretical interferential coating until a predetermined number or percentage of the collection of predictable interferential coatings is within the multi-dimension pairing range associated to the nominal residual color identifier of the theoretical interferential coating;
• and
• a deposition unit for depositing on an optical base element a stack of dielectric layers according to the theoretical interferential coating.