7.7.1 Sample Calculation 1: Uniform Illumination of Entire DMD Active Array (1280 × 800 pixels)
This calculation assumes that the entire DMD active array (1280 × 800) mirrors is uniformly illuminated with zero overfill falling outside the Pond of Mirrors pixel border. The highest DMD temperatures typically occur when the DMD mirrors are in the off-state (–12° landed) position. Therefore, the off-state fill factor calculates the worst case mirror temperature. Calculate the mirror temperatures to assess the viability of the illumination conditions.
- FFOFF-STATE-MIRROR = 75.3%
- MR @ 1064 nm = 94%
- αWINDOW@ 1064 nm = 0.7%
- RMIRROR-TO-SILICON = 3.39E5 °C/Watt
- RSILICON-TO-CERAMIC = 0.5 °C/Watt
- Array Resolution = 1280 × 800
- TCERAMIC = 30.0°C (measured)
- QINCIDENT = 160 W (measured)
- QELECTRICAL = 1.8 W
αDMD = [0.753 × (1-0.94)] + (1 - 0.753) + (2 × 0.007) = 0.31
QSILICON = 1.8 W + (0.31 × 160 W) = 51.4 W
QMIRROR = [(160W / (1280 × 800)] × 0.753 × (1 - 0.94) = 7.06E-6 W
Delta_TSILICON-TO-CERAMIC = 51.4 W × 0.5°C/W= 25.7°C
Delta_TMIRROR-TO-SILICON = 7.06E-6 W × 3.39E5 °C/W= 2.4°C
TMIRROR = 30.0°C + 25.7 + 2.4°C = 58.1°C