Retroreflective targets

FIGURE 5.10 Retroreflective targets are placed over the medial and lateral malleoli and femoral condyles (a). These anatomical targets are used to define the frontal plane of the shank (h). The X axis projects from the ankle Joint center toward the knee joint center. The axis lies perpendicular to the frontal plane, with the Z axis given by the cross product of X and Y. The orthogonal axes in the tight panel represent the ACS,h , which is located at the COM of the segment. 

The rectilineal or retroreflective explotron is simply a straight pipe or tunnel. At the upstream end there is sited the irradiable target T which, depending upon the power-... 

A reflective (also called bifurcated ) fiber is a fiber-optic assembly with the fibers from the emitter and receiver combined into a single unit. Reflective fibers can be used for direct reflective sensing in which the target object reflects the emitted light back to the fiber, or they can be equipped with a lens and reflector for use in the retroreflective mode. In the retroreflective mode, the emitted light bounces off a reflector and back to the receiver. The part breaks the beam to actuate the sensor. 

Minilight curtains can have a separate transmitter and receiver or a combination transmitter/receiver with a reflective target (see Fig. 15). The units with separate transmitter and receiver are usually easier to adjust and have a longer range than the retroreflective curtains. Retroreflective curtains are easier to install because you only have to run one set of wires. They have a shorter range because the light must travel twice as far (out to the reflector and back). 

Stuhlinger, T. Bidirectional reflectance distribution function of gold-plated sandpaper. Optical Eng. 22, SR-142 and Lea, T. K., and Schotland, R. M. (1988). Infrared retroreflecting lidar calibration targets. Appl. Optics 27, 208. Discuss gold-plated sandpaper, once widely used as standard for mid-IR diffuse reflectance. 

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