Investigation of the influence of broadband mechanical disturbances on the quality of recording interference patterns of GTE-wheel oscillations using a digital speckle pattern interferometer

Abstract

The effect of broadband disturbances on the operation of a noise-immune digital speckle pattern interferometer with a continuous wave laser emitter and a diffuse-scattering element arranged in front of an oscillating turbine wheel has been studied. Visibility dependences of the recorded interference patterns were obtained under the action of different types of artificially created disturbances. It is shown that the most dangerous mechanical disturbances for the operation of a speckle pattern interferometer are periodic noise and pink noise, whereas white noise and natural vibrations of the floor in the room where the experimental setup was accommodated do not significantly influence the quality of the information recorded by the interferometer. This article analyzes the influence of the mechanical properties of the diffuse-scattering element arranged in the speckle pattern interferometer on the quality of the obtained interference patterns. A relationship between the growth of forced tangential oscillations of the diffuse-scattering element and a decrease in the contrast of interference fringes was noted. In this case, an increase in the thickness of the organic glass plate of the diffuse-scattering element up to 8 mm leads to the neutralization of the pink noise action on the speckle pattern interferometer operation. At the same time, the effect of periodic noises decreases the contrast of interference patterns recorded for the cases of using 5 mm and 8 mm thick organic glass plates.

Keywords

• gas turbine engine
• the bladed wheel vibration
• registration
• speckle-interferometer
• mechanical perturbation
• interference pattern
• quality
• visibility