The shutter used in this proposed sensing module is shown in Figure 4. This shutter is commercially available and used in CCTV system. The shutter size is 3.4 cm by 2.0 cm. While the thickness and window diameter is 2.5mm and 10mm, respectively. This shutter operates on “on-state” at 3~5VDC and “off-state” at 0VDC. During “on-state”, the shutter consumed about 20mA.