Definition & Importance:
Optical efficiency quantifies the percentage of emitted light that reaches the viewer’s eyes after passing through the display’s optical layers (lenticular lenses, parallax barriers, etc.). Low efficiency leads to reduced brightness and higher power consumption.
Key Metrics:
- Luminance Transmission (%) –
- Ratio of output luminance (after optics) to input luminance (backlight/panel).
- Ideal: 50–80% for lenticular designs; <30% for parallax barriers.
- Angular Efficiency Drop-off –
- Brightness uniformity vs. viewing angle (e.g., ±30°).
- Tool: Coniometer or imaging photometer.
- Power Consumption per NIT –
- Measures energy cost of brightness (W/NIT) to compare efficiency trade-offs.
Measurement Protocol:
- Baseline Calibration:
- Measure native panel luminance without optical layers.
- Optical Layer Integration:
- Capture luminance drop after adding lenses/barriers.
- Viewing-Angle Sweep:
- Map efficiency vs. angle (critical for multi-view displays).
Improvement Techniques:
- Anti-Reflective Coatings: Reduce Fresnel losses.
- Optimized Lens Pitch: Balances efficiency vs. resolution.
- Hybrid Backlights: Directional LEDs minimize wasted light.
