The calculation of the optical power density of the illumination on the DMD in the different wavelength bands uses the total measured optical power on the DMD, percent illumination overfill, area of the active array, and the ratio of the spectrum in the wavelength band of interest to the total spectral optical power.

• ILL_UV = [OP_UV-RATIO × Q_INCIDENT] × 1000 ÷ A_ILL (mW/cm²)
• ILL_VIS = [OP_VIS-RATIO × Q_INCIDENT] ÷ A_ILL (W/cm²)
• ILL_IR = [OP_IR-RATIO × Q_INCIDENT] × 1000 ÷ A_ILL (mW/cm²)
• ILL_BLU = [OP_BLU-RATIO × Q_INCIDENT] ÷ A_ILL (W/cm²)
• ILL_BLU1 = [OP_BLU1-RATIO × Q_INCIDENT] ÷ A_ILL (W/cm²)
• A_ILL = A_ARRAY ÷ (1 ­- OV_ILL) (cm²)

where:

• ILL_UV = UV illumination power density on the DMD (mW/cm²)
• ILL_VIS = VIS illumination power density on the DMD (W/cm²)
• ILL_IR = IR illumination power density on the DMD (mW/cm²)
• ILL_BLU = BLU illumination power density on the DMD (W/cm²)
• ILL_BLU1 = BLU1 illumination power density on the DMD (W/cm²)
• A_ILL = illumination area on the DMD (cm²)
• Q_INCIDENT = total incident optical power on DMD (W) (measured)
• A_ARRAY = area of the array (cm²) (data sheet)
• OV_ILL = percent of total illumination on the DMD outside the array (%) (optical model)
• OP_UV-RATIO = ratio of the optical power for wavelengths <410nm to the total optical power in the illumination spectrum (spectral measurement)
• OP_VIS-RATIO = ratio of the optical power for wavelengths ≥410 and ≤800nm to the total optical power in the illumination spectrum (spectral measurement)
• OP_IR-RATIO = ratio of the optical power for wavelengths >800nm to the total optical power in the illumination spectrum (spectral measurement)
• OP_BLU-RATIO = ratio of the optical power for wavelengths ≥410 and ≤475nm to the total optical power in the illumination spectrum (spectral measurement)
• OP_BLU1-RATIO = ratio of the optical power for wavelengths ≥410 and ≤445nm to the total optical power in the illumination spectrum (spectral measurement)

The illumination area varies and depends on the illumination overfill. The total illumination area on the DMD is the array area and the overfill area around the array. The optical model is used to determine the percent of the total illumination on the DMD outside the array (OV_ILL) and the percent of the total illumination on the active array. From these values, the illumination area (A_ILL) is calculated. The illumination is assumed to be uniform across the entire array.

From the measured illumination spectrum, the ratio of the optical power in the wavelength bands of interest to the total optical power is calculated.

Sample calculation: