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OptiLayer:  Your Partner in Design and Post-Production Characterization of Optical Coatings


 Angle-Independent Color Mirror (Contest Problem)

In conjunction with the 2013 Optical Interference Coatings (OIC) topical meeting of the Optical Society of America (Tucson, Arizona), an angle-independent color mirror was a subject of a design contest held. Michael Trubetskov (developer of OptiLayer Software) and Weidong Shen (user of the OptiLayer Software) won this contest by submitting color mirror designs with a zero color difference between normal incidence and all other incidence angles up to 60° as well as
the thinnest design. Many designers used OptiLayer Software in order to solve design contest problems. Learn more about the contest...

  • In the design problem it is required to design a greenish-color mirror that maintains the same perceived specular reflected color, under D65 source.
  • Polarization of averaged, angular range is from normal incidence to 60 degrees.
  • In order to determine if the reflected color at oblique incidence is perceptually similar to the reflected color at normal incidence, each angular color difference is calculated from normal incidence (referred to as the “anchor color”) using a CIE color difference equation, CIEDE2000.
  • Layer Thickness ≥ 3nm, Number of Layers ≤ 2000.
  • Lightness: L* ≥ 30.
  • Chroma: Cab* ≥ 100.
  • Hue Angle: 120° ≤ hab ≤ 180°

multilayers color coordinates

All-Dielectric Solution:

nsub = 1.52, ninc = 1.0

Layer Materials:

F = 1.38

L = 1.45

B = 1.65

M = 1.8

T = 2.15

H = 2.45

 coating designs color properties
 OIC design contest

Design tricks and approaches:

  • The breaker condition and the most complicated part – minimization of the design total physical thickness;
  • It can be done with standard Gradual Evolution, Needle Optimization techniques
    in OptiLayer; 
  • A special additional experimental target for minimization of total thickness was implemented in OptiLayer.
  • Additional simplex-type fine tuning based on GPU (Graphics Processor Unit) computations was applied. NVidia GTX 580 was used. GPU code was about 5-8 times faster than code running at two six-core Xeon 3.8 GHz CPUs.


Metal-Dielectric Solutions:

  • Main problem with metal layers – if used at the beginning of computations they become too thick and “shield” the rest of the stack.
  • To prevent this, special Trapping option of OptiLayer has been applied. 
  • When layer thickness appears within trapping limits – it becomes constrained automatically!

OIC design contest

 OIC design contest

A winning result: Design has 121 layers, total physical thickness of 4782.80003 nm, DE2000 = 0; 13 thin Ag layers.


Learn more:

Easy to start

Icons 100x100 1OptiLayer provides user-friendly interface and a variety of examples allowing even a beginner to effectively start to design and characterize optical coatings.        Read more...

Docs / Support

Icons 100x100 2Comprehensive manual in PDF format and e-mail support help you at each step of your work with OptiLayer.



Icons 100x100 3If you are already an experienced user, OptiLayer gives your almost unlimited opportunities in solving all problems arising in design-production chain. Visit our publications page and challenge page.


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