Paul E. Bjork

High accuracy laser Doppler velocimeter using stable long-wavelength semiconductor lasers.

Doppler velocimeters for remote velocity sensing require a compact and miniaturized system. We report the achievement of an eye-safe Doppler velocimeter at 1.54microm using InGaAsP diodes reduced in linewidth by external cavity stabilization techniques. Linewidth of the diodes was of the order of 40 kHz allowing for a sub-cm/s velocity resolution over long distances (i.e., 100 m).

Optically Powered Sensors For EMI Immune Aviation Sensing Systems

Next generation digital flight control systems will require optical fiber technology to gain immunity to electromagnetic interference. A family of optically powered sensors currently in development and production will provide rugged, cost-effective alternatives for a variety of flight control and instrumentation needs.

Optically Powered Sensors: A Systems Approach To Fiber Optic Sensors

For more than 10 years fiber optic sensors have been projected as a dominant sensor technology for the future. This projection has yet to be realized. There continues to be a substantial level of research and development in various fiber sensors concepts yet only a few products are available commercially. The six major factors limiting the success of the fiber sensors in the marketplace are identified. An alternate approach to fiber sensors is described which take a systems approach to producing fiber sensors. It combines the advantages of optical fibers with the low power electronic sensor technology currently available. A single multimode fiber is connected between the readout and the transducer. Optical energy transmitted from the readout is converted to electricity at the transducer. Digital data from the transducer is synchronously transmitted over the fiber to the readout. Prototypes of magnetic (i.e., current), temperature, position, and proximity sensors have been built and will be described. A discussion comparing optical and electrical sensors is also included.

Fiber optic data bus for solid state sensors

A sensor system is described which is immune to EMI (electromagnetic interference) by combining a fiber-optic data bus with existing solid-state sensors. By optimizing the electrical design, through the wide variety of standardized circuits, this system allows for using a relatively inexpensive optical design based on standard optical components. Also power consumption can be traded off with added functions at the transducer end. With low-power electronics the options to address individual sensors, multiplex between sensors, change the sensor sample rate, and set threshold alarms are relatively simple compared to performing these functions with an optical scheme.<<ETX>>

Hybrid fiber optic sensors

For more than 10 years, fiber optic sensors have been projected as a dominant sensor technology for the future. This projection has yet to be realized. There continues to be a substantial level of research and development in various fiber sensors concepts, yet only a few products are available commercially. The major factors limiting the success of the fiber sensors in the marketplace will be identified. An alternate approach to fiber sensors is described which takes a systems approach to producing fiber sensors. It combines the advantages of optical fibers with the low‐power electronic sensor technology currently available. A single multimode fiber connected between the readout is converted to electricity at the transducer. Optical energy transmitted from the readout is converted to electricity at the transducer. Digital data from the transducer are synchronously transmitted over the fiber to the readout. Magnetic (i.e., current), temperature, position, and proximity sensors have been built and will be d...