Wide-range spectrum confocal displacement detection device

Abstract

The invention provides a wide-range spectrum confocal displacement detection device which comprises a white light source, a slit, a collimating lens, a beam splitter prism, a Fresnel lens, a detected object, a focusing lens and a spectrograph, and is characterized in that the white light source emits a beam of white light, the white light enters the beam splitter prism through the slit and the collimating lens, and is dispersed along the optical axis direction after passing through the Fresnel lens; light with different wavelengths converges at different positions of an optical axis, light beams focused on the surface of a measured object are reflected and returned along the same path, and the light beams pass through the beam splitter prism and the focusing lens and enter the spectrometer behind the slit. The spectrometer receives two specific wavelengths selected according to the confocal characteristics, and a corresponding focal length difference value, namely the displacement distance of the measured object, is solved according to the specific wavelengths. According to the device, light beams with different wavelengths are focused at different positions of an optical axis by using the Fresnel lens, so that axial dispersion is generated, and the limiting distance between focuses corresponding to the wavelengths of the light sources is greatly increased, so that the measuring range of the displacement detection device is expanded by two orders of magnitude.

Description

technical field [0001] The invention belongs to the field of optical non-contact precision displacement measurement, in particular to a large-range spectral confocal displacement detection device. Background technique [0002] Spectral confocal displacement detection is a precision displacement measurement device. The principle is: a beam of polychromatic light (white) is emitted from the light source, and it is focused on the surface of the measured object through the lens group to form monochromatic light of different wavelengths within the range. The focal point of a wavelength corresponds to a distance value. The measuring light hits the surface of the object and is reflected back. Only the monochromatic light that meets the confocal condition can be sensed by the spectrometer through the slit, and the displacement distance of the measured object can be obtained by calculating the focus difference corresponding to the detected light wavelength. The spectral confocal dis...

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Problems solved by technology

But the range of the invention is only about 2 mm

In addition, Zhong Xiang, Gui Dongliang and others from Hefei University of Technology invented a spectral confocal displacement sensor based on chirped fiber gratings. The patent authorization number is CN 110567379 B, and the authorization date is March 30, 2021. The invention is Dispersion is achieved by using chirped fiber gratings, instead of complex dispersion lenses, and the miniaturization of the precision measurement system is realized, but the range of the invention is also reduced to 50 microns, which shows that the spectral confocal displacement in the prior art The measuring range of the sensor is limited, which limits the application range of the device

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