The Ego system allows the independent positioning anywhere on a 2m-radius hemisphere, of a light source (or equivalent) and a detector directed at a central target. This arrangement allows bi-directional reflectance measurements under controlled laboratory conditions. To reduce light scattering, the goniometer is painted black and accommodated in a special black laboratory featuring light absorbing rubber floor material. Sources and detectors are mounted on carriages running on rails in a vertical arc to give elevation. The vertical arcs are rotated on horizontal circular rails to give azimuthal positioning.
- Source (outer) horizontal and vertical rail diameters: 4.8m.
- Detector (inner) horizontal and vertical rail diameters: 4.4m.
- Maximum source or detector weight: 15kg.
- Source/detector azimuth range 0° to 360° in 0.01° steps: accuracy ±0.1°.
- Source/detector elevation range 0° to 90°in 0.01° steps: accuracy ±0.1°.
- Measurements are possible at near-grazing angles.
- Angular velocity: 1°/s on azimuth, 0.5°/s on elevation.
- Target size max. 1m×1m, min. 50mm×50mm. Requirement for manual handling limits weight.
- 360° target rotation, 60° range of tilt.
- All movements are computer-controlled.
- Calibrated PTFE panel reference standards available.
- Various laser or lamp sources.
- High-resolution CCD camera.
This facility is suitable for characterizing the bi-directional reflectance properties of targets. There is also scope for evaluating or optimizing the angular response characteristics of prototype detection equipment.