Methods and systems are disclosed for reducing signal interference between Bluetooth and WLAN communications in an information handling system. The method obtains a first content item from an online source, and selects only a portion of the words in the first content item, in accordance with a defined selection algorithm. A region of interest is extracted from the image, roughly corresponding to the designated field. That is, no air reservoir is formed between an electron incidence part 15a at the center of the semiconductor device 15 and the surface C of the stem 11, whereby air expanding at high temperature does not damage the electron incidence part 15a of the back-illuminated semiconductor device 15. Random variations due to manufacturing process can be averaged out by a plurality of the V-grooves and high precision can be obtained by the present invention.