Powell prism related knowledge introduction
2022-8-22
Powell Prism is a kind of optical scribing prism, which allows the laser beam to pass through to optimally scribing into a straight line with uniform optical density, good stability and good linearity. Powell prism scribing is better than the scribing mode of Cylindrical Lens, which can eliminate the central hot spot and faded edge distribution of the Gaussian beam.
Fan angle
The fan angle width is a function of the refractive index of the glass and the apex angle. The higher the top tilt, the greater the refractive index of the glass, and the greater the fan angle at the same projection distance. Small fan angles usually use optical glass with refractive index n=1.5, and large fan angles usually use high refractive index glass with n=1.8, or increase the top tilt angle.
Laser beam size
In the case of a certain projection distance, the size of the incident laser beam determines the thickness of the laser line. A parallel laser beam with an elliptical cross-section may produce two wide or narrow straight lines.
When the Gaussian laser beam passes through an ordinary cylindrical lens, it will produce unevenly distributed straight lines, while the top of the Powell prism is a complex two-dimensional aspheric surface. When the laser passes through, a large amount of spherical aberration will be generated, redistributing the optical path and reducing the central area The light at the edge increases the light at the edge to form a uniform straight line, which is suitable for various machine vision applications such as biomedicine, automobile assembly, and food processing.
Fan angle
The fan angle width is a function of the refractive index of the glass and the apex angle. The higher the top tilt, the greater the refractive index of the glass, and the greater the fan angle at the same projection distance. Small fan angles usually use optical glass with refractive index n=1.5, and large fan angles usually use high refractive index glass with n=1.8, or increase the top tilt angle.
Laser beam size
In the case of a certain projection distance, the size of the incident laser beam determines the thickness of the laser line. A parallel laser beam with an elliptical cross-section may produce two wide or narrow straight lines.
