Patent ID: 8481975
Filing Date: 2013-07-09
Classification: G01B

Abstract:
1. A process for detection of, a turbine blade surface, the process including the following steps: providing a turbine blade having a surface to be detected; applying a washable film to the surface to be detected, the film being made of a fluorescing material which, when irradiated with electromagnetic radiation from a first wavelength range from 350 nanometers to 410 nanometers, emits electromagnetic radiation in a second, visible light, wavelength range, the washable film consisting of fluorescing dyes, a solvent, esters and surfactants in a washable solution; providing a radiation pattern projection device, having, as a sole light source, a laser light source that emits radiation in a defined wavelength range from 400 nanometers to 410 nanometers and a digital micromirror device for projecting a radiation pattern by reflecting light from the laser light source, the digital micromirror device including a window and a plurality of micromirrors coated with polished aluminum and having a reflectivity of 90 percent of radiation in the defined wavelength range of from 400 nanometers to 410 nanometers and wherein the micromirrors are hermetically sealed at reduced pressure and positioned behind a window transparent to radiation in the defined wavelength range of from 400 nanometers to 410 nanometers and irradiating the washable film on the turbine blade surface to be detected, in parts, in a temporal sequence, with a projected radiation pattern using electromagnetic radiation projected with the radiation pattern projection device in the defined wavelength range; providing a filter for filtering out radiation in the defined wavelength range and filtering out radiation in the defined wavelength range from 400 nanometers to 410 nanometers from visible light emitted by the washable film upon irradiation with the radiation pattern projection device and receiving the filtered radiation emitted from the washable film on the surface of the turbine blade with a stereo camera; recording, with the stereo camera, in the wavelength range of visible light a series of temporally altered pictures using the filtered received radiation; providing a computer assessment unit that calculates a three-dimensional contour of the turbine blade surface to be detected based on the assignment of the recorded picture(s) to the projected pattern(s) and analyzing the three-dimensional contour of the turbine blade surface with the computer assessment unit; and washing the washable film, including the fluorescing dyes, solvent, esters and surfactants, away from the turbine blade surface after analyzing the three-dimensional contour of the turbine blade surface with the computer assessment unit.