# Study of Exposure Uniformity of UV LED Exposure System for Wafer-Level Camera Lenses
## 3 Results  
### Parameter Design Change of Type A  
We then change the design variables for type A (Figure 10) to find a better combination. From the previous simulation results, it is known that the current center of the light intensity is too strong.  
\begin{table}
\begin{tabular}{c c} \hline
**Reflective Cover** & **Uniformity** \\ \hline type 1 & 87.84\% \\ type 2 & 85.84\% \\ type 3 & 90.91\% \\ \hline \end{tabular}
\end{table}
Table 5: Uniformity of reflective cover type simulation results.  
Figure 9: Simulation results of each reflective cover type: (**a**) Results of the reflective cover type 1, (**b**) Results of the reflective cover type 2, (**c**) Results of the reflective cover type 3.  
The design variables are the distance \(W\) in the transverse and vertical direction of the center outer area, and the distance \(D\) in the transverse and vertical direction of the center area.  
The new parameter are as follows:  
Type (a): \(D\) = 1.44 cm, \(W\) = 1.44 cm; Type (b): \(D\) = 1.6 cm, \(W\) = 1.36 cm; Type (c): \(D\) = 2 cm, \(W\) = 1.16 cm; Type (d): \(D\) = 2.88 cm, \(W\) = 0.72 cm. The LED arrangement and simulation results are shown in Figures 11 and 12 and Table 6.  
Figure 11: LED arrangement of each type: (**a**) Type (**a**), (**b**) Type (**b**), (**c**) Type (c), (**d**) Type (d).  
Figure 10: Parameter design change model of type A.  
Type (a) is the original design type A, and the results show that the luminous intensity was stronger in the center, so gradually increase the distance \(D\) of the center to increase the uniformity. The results show that as \(D\) rises, W decreases and evenness increases, with type (d) having the greatest uniformity. This study will thus aim to improve type (d).  
Since the previous simulation results show that the center of the light intensity is slightly weak, so we added four LED to the central try and increase this, As shown in Figures 12(a) and 13(a), there is then a significant improvement in uniformity (Table 7).  
However, the light intensity of the edge is also observed to be weak, resulting in a decrease in the overall uniformity, as shown in Figures 12(b) and 13(b). We thus removed 4 LED from the central area and found that its uniformity slightly increased. As shown in Figures 12(c) and 13(c), the uniformity increased from 88.47% to 90.34%.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Type** & **Uniformity** \\ \hline type (a) & 84.86\% \\ type (b) & 85.86\% \\ type (c) & 87.55\% \\ type (d) & 94.53\% \\ \hline \hline \end{tabular}
\end{table}
Table 6: Uniformity of type A of each design variables simulation results.  
Figure 12: Simulation results of each type: (a) Results of type (a), (b) Results of type (b), (c) Results of type (c), (d) Results of type (d).  
The results can be summarized as follows:  
1. The best type of reflective cover: _h1_ is 3 cm and _h2_ is 1 cm. When a smaller _h1_ value and a larger _h2_ value are selected, the periphery LED light source is refracted to the central area by the action of the reflector cover, so that the central light intensity is greater than the periphery intensity, and the uniformity is lowered.
2. Increasing the \(D\) value can effectively increase the overall uniformity. When the value of D is larger (the number of LEDs in the central area is reduced), the refraction and overlap of the periphery LED light sources do not cause the center intensity too strong.
3. When the above 1. and 2. are executed, the difference between the light intensity of the center and periphery becomes smaller, appropriately increasing the number of LED on the periphery can make the overall uniformity rise.
4. Based on the above simulation results, we use these concepts applied to the design change, type 4 of design change (IV) is a good arrangement in the simulation.  
These simulation results can be applied with the actual model arrangement to improve the uniformity.