Abstract: Optical delay line system that includes a retro-reflection mirror which is displaced along a circular path while being maintained in angular alignment with launch and return sources of light subject the components of the system to minimum levels of unbalanced linear acceleration. A retroreflector is pivotally mounted on a rotating element such that the optical axis of the retroreflector's motion is mobile such that its angle or position changes relative to a fixed observer. There is no linear stopping and starting of the retroreflector and all acceleration of the retroreflector is rotational acceleration with small angles so the required forces in the optical delay line are greatly reduced. Both large displacement and high repetition rates are achieved. The system can be configured so that optical fibers serve as launch and return optics. Alternatively, free space beam paths deliver light to the optical delay and return the reflected light from the retroreflector.

Abstract: Fiber optic sensors employ a high brightness light source such as a fiber optic supercontinuum source, multiplexed superluminescent light emitting diodes, or a broadband tunable laser diode. Light is delivered to the measurement location via fiber optics and sensor optics directs infrared radiation onto material the being monitored that is located in a hostile environment. A disperse element is positioned in the detection beam path in order to separate the wavelengths and to perform spectral analysis. A spectral analysis of the radiation that emerges from the sheet yields information on a plurality of parameters for the material. For papermaking applications, the moisture level, temperature and cellulose content in the paper can be obtained.

Abstract: Optical delay line system that includes a retro-reflection mirror which is displaced along a circular path while being maintained in angular alignment with launch and return sources of light subject the components of the system to minimum levels of unbalanced linear acceleration. A retroreflector is pivotally mounted on a rotating element such that the optical axis of the retroreflector's motion is mobile such that its angle or position changes relative to a fixed observer. There is no linear stopping and starting of the retroreflector and all acceleration of the retroreflector is rotational acceleration with small angles so the required forces in the optical delay line are greatly reduced. Both large displacement and high repetition rates are achieved. The system can be configured so that optical fibers serve as launch and return optics. Alternatively, free space beam paths deliver light to the optical delay and return the reflected light from the retroreflector.

Abstract: A scanning system includes a cable take-up mechanism that uses a series of pulleys that determine the bend diameters of a scanning system. The mechanism is particularly suited for a spectrometric, e.g., infrared, scanning system where moving scanner or sensor head essentially houses only the optical elements while essentially of all the other electronic and optical components associated with the measurement are housed in an easily accessible compartment that is remote from the moving scanner head. Light is transmitted through optical fiber cables. The cable take-up mechanism maintains the fiber optic cable at essentially constant total bend length and bend diameter thereby minimizing any dynamic changes to spectral bend losses as the optical head is scanned. The light weight construction of the sensor head further reduces vibrations associated with the moving scanner head.

Abstract: A compact, long lasting sensor for measuring components such as moisture in moving sheets including paper in a papermaking apparatus employs light sources that produce radiation within defined wavelength regions of interest and the light sources are modulated at high frequencies using non-mechanical techniques. A single detector with various radiation sources can measure at all frequencies while keeping information separated. Superluminescent light emitting diode or laser diode light sources can be directly electrically modulates for improved noise rejection. These higher power and bright light sources afford excellent fiber optic launch efficiency and permits the sensor to be scanned at much faster rates over the paper being monitored.

Abstract: A method and apparatus for controlling the state of a pneumatic actuator having a valve that connects the actuator to a supply pressure and a valve that connects the actuator to an exhaust pressure. The method involves closing the supply pressure and exhaust pressure valves, determining the current state of the pneumatic actuator, and then determining the difference between the current state and a desired state. The appropriate pressure valve to be opened and the period to be opened is then calculated based on pre-determined calibration data for the actuator which permits the end state of the actuator to be predicted. The appropriate valve is then opened for the calculated period to adjust the actuator to the desired state. The process is then repeated until the current state of the actuator is the desired state. A controller unit that uses the above method is also disclosed.