Tham khảo tài liệu 'photodiodes communications bio sensings measurements and high energy part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | UV Photodiodes Response to Non-Normal Non-Colimated and Diffusive Sources of Irradiance 191 which is in this case blocked . By doing this we evaluate the unfiltered contribution of a direct beam . the direct beam photons that reach and excite the sensing dice avoiding the nominal FOV and thus avoiding the filter. The photodiode base was glued again to the can. Notice that after this manipulation the TO5 cage is filled in by ambient air instead of the original nitrogen encapsulation. Fig. 5. Zenithal angle dependence of the responsivity to an inclined collimated beam for the SiC unfiltered photodiode ABC and 5 filtered photodiodes A B C D and E . Comparison of the angle dependence between cosine-like decay and a polynomial fit of the measured data with angle. Notice that for a collimated source the photodiodes show significant responsivity beyond the nominal FOV of 30 . In Figure 6 we show the spectral response of this open-blocked photodiode and compare it with the one of a normal C photodiode. Be aware that the filter partially transmits partially reflects and partially absorbs. Each specific filter has a different behaviour with respect to transmission and absorption tuned to select the transmissions properties only. When photons are trapped below the filter bouncing back and forth until they hit the dice the filter may also absorb a spectral part of the irradiance. In this specific example a relevant part of the signal of the UVA range seems to be partially blocked but most of the UVB range radiation is hitting the SiC dice through secondary wall reflections creating a current leak. Thus we may expect different responses for blocked photodiodes of different filters. As we will see later this is indeed observed. Characterization of the angular response of the non-filtered contribution with a divergent beam To qualitatively evaluate under laboratory conditions the angular response of the unfiltered contribution a new photodiode was manipulated to separate .
