Performance data characterizing a direct optical activation device that operates either pneumatically or hydraulically are presented. This direct conversion device for optical signals offers immunity to electromagnetic interference and provides an alternative to electrooptic and electromechanical valves for actuation. The device uses a modified fluidic laminar proportional amplifier, employing laser induced deflection of the fluidic supply jet to perform the signal conversion. The pneumatic version operates at a supply pressure of 20.7 kPa having a gain of 15.5 kPa/W of optical power and a bandwidth of 140 Hz. The hydraulic version of the device operates with MIL-5606 hydraulic oil pressurized to a supply pressure of 1300 kPa. The hydraulic version has a gain of 170 kPa/W of input optical power and a bandwidth of 170 Hz. Experiments have determined that the laser induced deflection of the supply jet is a result of optical modulation of the fluid viscosity which creates an asymmetric jet flow.

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Detection of airfoil time of arrival with optical probes has been evolving since the 1980s. Time of arrival data are used to infer airfoil stresses caused by vibration through a sequence of manipulations. The data conversion begins by converting arrival time to blade position, so blade deflection can be determined from the expected non-vibrating position. Various methods are used in the industry to convert deflection data to frequency, amplitude, and stress, which is beyond the scope of this paper. Regardless of the analytical approach used, producing accurate stress information relies on the precise detection and measurement of time of arrival, which equates to blade position. Recent improvements have been made in time of arrival system accuracy by running faster clocks to increase temporal resolution of the measurement. Greater timing resolution, afforded by clock speed, will have diminishing returns when probe and blade-tip interactions begin producing dominant errors. In the case of optical probes, the blade-tip needs to be treated as a curved reflector in the optical system that is capable of introducing dynamic errors. In engine operation the blade-tip moves axially under the probe from untwist, static deflection, and vibration, causing the light to reflect from different parts of the blade-tip. This relative movement between the probe and blade-tip cause the arrival time to change dynamically. Neglecting the dynamic arrival errors caused by the blade-tip’s optical properties will result in blade deflection-errors that propagate into the stress information. This paper presents a laboratory study that quantifies time of arrival errors due to optical interaction with tip radii. The study reports measured arrival position error as a function of location and optical signal power levels. The work is presented in terms of arrival position, producing information that is independent of rotational speed, and vibratory mode.