The amount of optical overfill on the
critical area of the window aperture cannot be measured directly. For systems with uniform
illumination on the array the amount is determined using the total measured incident optical
power on the DMD, and the ratio of the total optical power on the DMD that is on the defined
critical area. The optical model is used to determine the percent of optical power on the
window aperture critical area and estimate the size of the area.
- QAP-ILL =
[QINCIDENT × OPAP_ILL_RATIO] ÷ AAP_ILL
(W/cm2)
where:
- QAP-ILL = window aperture
illumination overfill (W/cm2)
- QINCIDENT = total incident
optical power on the DMD (Watts) (measured)
- OPAP_ILL_RATIO = ratio of the
optical power on the critical area of the window aperture to the total optical power on
the DMD (optical model)
- AAP-ILL = size of the window
aperture critical area (cm2) (datasheet)
- OPCA_RATIO = percent of the
window aperture critical area with incident optical power (%) (optical model)
Sample
calculation:
Figure 6-2 Window Aperture Overfill Example
See the figure for the length of the
critical aperture.
Equation 22. QINCIDENT = 80W (measured)
Equation 23. OPAP_ILL_RATIO = 0.312% (optical
model)
Equation 24. OVCA_RATIO = 25% (optical
model)
Equation 25. Length
of the window aperture for critical area = 1.8613cm (data
sheet)
Equation 26. Width
of critical area =
0.050cm (data
sheet)
Equation 27. AAP-ILL = 1.8613cm × 0.050cm = 0.093065
(cm2)
Equation 28. QAP-ILL = (80W × 0.00312) ÷ (0.093065cm2 × 0.25) =
10.7 (W/cm2)