The emergence and development of any industry is inseparable from the progress of science and technology, which is also the continuous expansion of market demand to promote the industry, prompting relevant personnel to constantly update products. The development of spectral confocal displacement sensor is also changing rapidly.

 

 

A beam of white light (or multi-wavelength mixed light) through a small hole, through the lens focusing on different wavelengths on the optical axis, dispersing to form a rainbow distribution band, shining on the sample, part of the reflected light reflected back; The light that shines at the intersection of the optical axis and the surface of the object passes through the spectroscopic part and shines through the aperture to the spectral analyzer. Based on the wavelength calculation, the distance from the lens to the measured object can be obtained. At the intersection of the optical axis and the surface of the object no unilluminated light passes through the split part and is blocked around another small hole.

 

                          

 

 

 

In the spectral confocal sensor system, the measuring range of the system is affected by four factors: the spectral distribution range of the light source, the axial chromatic difference of the operating band dispersive lens, the operating band of the spectrometer, and the operating band of the fiber coupler. Select a white LED spectral distribution wavelength range of 400-800nm. Therefore, in the design process of the spectral confocal sensor, the operating band of the dispersive lens, spectrometer and fiber coupler should be as consistent as possible with the band of the light source. The measuring range of the system is its usual dispersive mirror. The axial color difference of spectral confocal sensor in the working band range.

 

In the design of dispersive lens, spectral confocal sensor should not only consider the axial color difference, but also consider the following factors: first, increase the object side numerical aperture can improve the resolution; Secondly, increasing the numerical aperture of the image side can improve the utilization rate of the light source. Then reduce the spherical error of the system and improve the accuracy; The system structure of the spectral confocal sensor should be easy to assemble and adjust.

 

If we want to correct the spherical aberration system, the system and structure will become complicated, so the dispersive lens of the spectral confocal sensor is designed to use very few lenses to achieve better results. The optical system of a spectral confocal sensor can be seen as two parts. One part is a chromatic aberration mirror, which focuses on the light source, and the point light source is collimated into parallel light, and the other part is a dispersion mirror. Its function is to focus parallel wavelengths of light at different locations on the axis, resulting in spectral dispersion, which can be achieved by color difference elimination lenses and aspherical lenses. The optical fiber coupler with high coupling efficiency in the light source band is selected, and the resolution is 0.5nm spectrometer.

 

 

1. Surface roughness measurement application Surface roughness refers to the micro-level state formed by the precision of machine tools and tools, workpiece processing surface vibration, wear and other factors in the processing process due to different processing methods, small spacing, small peaks and valleys, which is an important indicator to measure surface quality, related to the wear, sealing, lubrication, fatigue, research and other mechanical properties of parts. Surface roughness measurement can be divided into contact measurement and non-contact measurement. The touch needle contact measurement is easy to scratch the measuring surface, the tip is easy to wear, the measurement efficiency is low, and the complex surface can not be measured. The non-contact measurement can be relatively realized, and the efficient and online real-time measurement has become the development direction of the future roughness measurement.

 

At present, the commonly used non-contact methods mainly include interference method, scattering method, speckle method, focusing method and so on. Among them, focusing method is simple and practical. The spectral confocal displacement sensor is used to measure the roughness of the valve cover of the film gas meter to determine whether the seal of the valve cover is qualified, and some results are obtained. Based on the spectral confocal sensor, the surface roughness of the roughness sample block was measured by a two-dimensional nano-measuring and positioning device without contact, and the uncertainty evaluation of the measurement results was carried out, U95 was 13.9%.

 

2. With the development of processing level, more and more small complex workpieces need to be profiled and precision dimensional measurement, such as measuring the chamfer of a small circle and measuring the inner wall slot size of a small workpiece. Some precision optical components also need to measure contactless contours to avoid scratching the optical surface during contact measurement. Spectral confocal sensors can be used to solve these measurement problems that are difficult to solve with traditional sensors.

 

Aiming at the problem of turbine wheel profile detection, a spectral confocal displacement sensor is used to design an online detection system for turbine wheel profile. The spectral confocal sensor is used as the measuring head to realize the two-dimensional dimension measurement of ultra-precision parts through the self-built two-dimensional nano measuring and positioning device. Laser confocal displacement meter combined with two-dimensional precision control micro-platform was used to scan the surface fluctuation depth of Xihan sunglasses and explore the imaging principle of light mirror reflection.

 

3. Because the wavelength of the monochromatic light reflected by the spectral confocal sensor is different from that of the different reflective surfaces, the thickness measurement of the thin film material has unique advantages. Optical glass. Biofilm. For parallel tablets, etc., two reflecting surfaces reflect monochromatic light of different wavelengths, and then only one sensor can calculate the thickness, and the measurement accuracy can reach the micron level without damaging the measurement surface. The application of the spectral confocal displacement sensor to measure the thickness of transparent materials is discussed. The measuring error range of the system is about 0.005mm. It provides a method to measure the center thickness of a parallel tablet computer and an optical lens by using a spectral confocal sensor, and theoretically analyzes the influence of the material dispersion of the measured object on the thickness measurement accuracy.

 

In order to explore the relationship between the film thickness prepared by the fluid descending mode and the descending mode, the Reynolds number and the tilt Angle of the substrate, the spectral confocal sensor is used to monitor the film thickness and thickness in real time and the experimental setup. The white light confocal sensor group installed on the top is 10~100μm thick to accurately measure the thickness and distribution of the metal film, analyze the measurement uncertainty, and obtain the measurement uncertainty of the system is about 0.12μm.

 

Spectral confocal technique establishes a set of coding rules of axial distance and wavelength, which is a high precision coding rule non-contact optical measurement technique. The sensor based on spectral confocal technology is a kind of sub-micron sensor, and the surface micro-shape is widely used in the field of fast and accurate measurement of sensors, thickness measurement, displacement measurement, on-line monitoring and process control. Looking forward to the future, with the development of spectral confocal sensing technology, it will certainly appear in the field of microelectronics, linewidth measurement, nano testing, ultra-precision geometric measurement and other fields.