# The 2017 IODC Illumination Problem

## The Centennial Illuminator

### Problem Description

2016 is the 100th anniversary of the Optical Society of America – its Centennial year. To celebrate this, the 2017 IODC Illumination Design Problem (announced in 2016) has a centennial theme.

The problem is to create an emissive ‘100’ logo for the anniversary.  We have two planar Lambertian disc sources (radius=1) that emit into the positive (+z) hemisphere, however we are missing the ‘1’:

Figure 1. Illustration of the planar disc sources

In order to create the numerals ‘0’, a 90% reflective disc covers each center of the two disc sources.  The source light that is reflected by the discs is heading into negative (-z) hemisphere. The goal is to couple that reflected light into the ‘1’ to maximize the logo luminance while keeping the average luminance of all three numerals the same.  The radius of the reflective disk should be between 0.01mm and 0.99mm.

The area between the numerals and the negative z side of the disc sources is absorbing, except for the area corresponding to  the reflective discs.   The rectangular target region (size 0.5×2.0) for the ‘1’ has a thin Lambertian diffuser that transmits 45% of the incident light and reflects 45%.  This ensures luminance versus angle is constant. The 1+0+0 are all in a plane. The coupling optics must be located between z = -0.5 and z = -100. An annular partial absorber that covers the disc sources is placed on the +z side of the disc source.  The transmission of the partial absorber is adjusted to ensure that the average luminance of the 1 is the same as the 0’s.  The goal is to maximize logo flux while maintaining uniformity.

Figure 2. Illustration of the final appearance of the anniversary logo using disc radius=0.4

Figure 3. Cut-away side view of the ‘0’ with source, annular absorber (back side of source), annular partial absorber (front side of source), and reflective disk.

[table caption=”

### Specifications

” colwidth=”120|300″ delimiter=”|” th=”0″ nl=”~~”]

Sources:|   2 planar uniform monochromatic Lambertian disc sources (1W each)~~Size: Radius=1~~Position: Source 1 (x=0, y=0, z=0), Source 2 (x=2.25, y=0, z=0)~~Surface Normal and emission: into positive z-direction

Back Reflectors:|              Planar circular mirrors located concentrically at the center of the disc sources~~Radius is variable between 0.01 and 0.99mm~~Reflectivity 90% (10% absorption)

Target area:|                     Shape Numeral ‘1’~~Size:  0.5 x 2 (Area =1)~~Center Position: (x=-1.5, y=0, z=0)~~Thin Lambertian diffusor with reflectivity 45% and transmission 45%

Detector:|  To cover the full ‘100’ logo, slightly shifted to positive z=0.001 to only be sensitive to light in the positive z-direction

Optics:|   Bulk-Material:  Plastic with index n=1.5.  Bulk absorption follows Beers law with 99% transmission for 1mm thickness.~~Specular surfaces have 96% transmission and 4% reflection except where TIR occurs.  For TIR angles, 0% transmission and 100% reflection is assumed.~~Specular Mirrors – Reflectivity 90%~~Diffuser Reflectors – Lambertian with 98% Reflectivity~~Partial Absorbers – Transmission variable between 0 and 100% (0% reflection).~~Location: All optics (except for the 2 disc sources, 2 disc reflectors, partial absorbers, and the target Lambertian diffuser area) must be located between z=-0.5 and z=-100mm~~All polarization and diffraction effects are to be ignored.

Wavelength:|                     550 nm. No wavelength conversion allowed.

[/table]

### Merit Function

The goal of the problem is to maximize the flux that is transmitted from the full ‘100’ logo into the positive z-direction (this includes the light from the two annular 0’s that passes through the partial absorber and the light that propagates through the ‘1’ target’s Lambertian diffuser).  Only light travelling in the positive z-direction is considered. The average luminance of the ‘1’ and the two ‘0’s should be equal. When the partial absorber that covers the annular region of the ‘0’s is considered, the full ‘100’ logo flux is Flux1(1+2π(1-R2disk)), where Flux1 is the flux that is transmitted through the ‘1’.

The uniformity in the ‘1’ should be >30%. The spatial luminance in the ‘1’ shall be analyzed on a grid of 10 x 20 rectangular bins. Each bin has .05 mm width and 0.1 mm height.  The bin with the least amount of flux must be greater than 30% of the flux in the bin with the most flux.

### Submissions

The prize will be awarded to the entrant with the highest flux [W] on the detector.  A special prize will also be given to the best student submission.

The evaluation committee includes Bill Cassarly, Alois Herkommer, and Henning Rehn. Please send your entry to williamc@synopsys.com. Please include the following information with your submission:

• Name,