New Ideas in Fiber Transmission
Fiber optic transmission has become the preferred method of transmission for both point-to-point video and data or Ethernet over fiber. In their most basic operation both are extremely effective ways of delivering video and data from a remote surveillance location to monitoring station or stations. Both have distinct benefits and drawbacks. IP video over fiber offers the capability of redundancy, multiple location monitoring and scalability. But the downside is complexity that in many instances requires network experts to implement and in some cases offers less than great quality video. Point-to-point systems offer simplicity to the point of being plug and play and easy to install and are known for DVD quality real-time video and the capability to transmit multiple channels of video over a single fiber. The downside is, if the fiber is compromised, the video is gone and in most cases monitoring can take place in one location. The ComNet SHR fiber optic product line offers the capability to currently insert and drop up to eight channels of 10-Bit digital video and eight channels of serial data onto a fiber optic network with distances as far as 48km between nodes. The video and data can be extracted at an unlimited number of locations. The additional use of a second fiber ensures redundancy to the network eliminating a single point of failure. These two features plus the ease of installation give the user a simpler installation while retaining the beneficial functionality of an Ethernet-based system.
A major event in the evolution of OCT was the use of light wavelengths instead of time delay to determine the spatial location of reflected light. Through the use of Fourier transformation, this took the technology from the original method of TD-OCT to the development of SD-OCT. The original OCT method, known as TD-OCT, encoded the location of each reflection in the time information relating the position of a moving reference mirror to the location of the ,45 SD-OCT, instead, acquires all information in a single axial scan through the tissue simultaneously by evaluating the frequency spectrum of the interference between the reflected light and a stationary reference mirror. This method enables much faster acquisition times, resulting in a large increase in the amount of data that can be obtained during a given scan duration using SD-OCT. A comprehensive review of SD OCT by Joel Schuman is available(10)