|
Optical RFID (aka OPID) is an alternative to RFID that is based on optical readers. Applications for optical RFID tags may be found in future supply chain scenarios. The main advantage in comparison to traditional RFID tags is their low price and the usually employed offline preaggregation of data to the class level. Unlike most other RFID chips (which use radio frequencies of 0.125–0.1342, 0.140–0.1485, 13.56, and 868–928 MHz), optical RFID operates in the electromagnetic spectrum between the frequencies of 333 THz (3.33×1014 hertz, 900 nm) and 380 THz (788 nm) and 750 THz (400 nm). The tag information is communicated to the reader by reflecting the read request. Parts of the incoming signal are filtered by the tag in a well-defined way as it is sent back to the reader. On the reader's side, the tag data can be deduced by analysing the pattern used for filtering. As an alternative to reflection mode, active circuits can be used, replacing awkward RFID antennae with photovoltaic components and IR-LEDs on the ICs. Kodak has also announced an OPID product for tracking pharmaceuticals. One of the earliest examples of Optical RFID is (RFIG: Radio Frequency Identity and Geometry ), by Ramesh Raskar, Paul Dietz, Paul Beardsley and colleagues. This combines an optical tag with a RF tag to provide ID as well as geometric operations, such as location, pose, motion, orientation and change detection. Regarding privacy, optical RFID provides much more protection against abuse than RFID based on common electromagnetic waves. This is mainly because line-of-sight is required for malicious read out. Such an attack can easily be prevented with low cost optical RFID sight blockers. Nevertheless if needed some penetration of solids and liquids can be achieved e.g. with near-IR wavelengths. == References == 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Optical RFID」の詳細全文を読む スポンサード リンク
|