tailieunhanh - Nonimaging Optics Winston Episode 10

Tham khảo tài liệu 'nonimaging optics winston episode 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Translational Symmetry 259 operating every day of the year from sunrise to sunset. The formulas for the target and source étendue are given in Eqs. and respectively. We assume the total surface area of the target is Atrg 1m2. Eq. then allows us to calculate the target étendue e trg p m2 sr. When the source étendue is set equal to the target étendue Eqs. and give the following value for the total surface area of the source Asrc m2. For this equal-étendue case Figure depicts the skewness distributions of Eqs. and . The upper limit on étendue that can be transferred from the source to the target by a translationally symmetric concentrator is computed using the integral of Eq. . For the equal-étendue case this upper limit on transferred étendue turns out to be emax m2sr. With reference to Figure this étendue limit is equal to that portion of the étendue region contained under the source s skewness distribution that is intersected by the étendue region contained under the target s skewness distribution. As indicated by Eqs. and the upper limits on efficiency and concentration are computed by dividing emax by the total source and target étendue respectively. For the equal-étendue case the efficiency and concentration limits have the same value hmax Cmax . Translational skewness unitless Source ----- Target Figure Translational skewness distributions in a unit-refractive-index medium for a Lambertian target and a source having fixed latitudinal cutoffs parallel to the symmetry axis. The angular half width of the source is Q0 . The source étendue equals that of the target. 260 Chapter 10 Consequences of Symmetry Using Eqs. and we can also compute the efficiency and concentration limits for source-to-target étendue ratios other than unity. The resulting efficiency limit is plotted as a function of the concentration limit in .