Narrow Beam Width Scheme Of Blue Structured Light Based On Gradient-index Lens

Blue structured light has important application prospects in three-dimensional imaging,laser ranging and other fields due to its short wavelength,energy concentration and low transmission loss.In blue structured light system,laser diode is usually used as light source,and the laser divergence angle of output is generally large.At the same time,the divergence angle of fast axis and slow axis are different.Therefore,the beam emitted from the blue structured light system cannot be used directly.Using the Gradient-index lens with large numerical aperture has the advantages of high coupling efficiency,high energy utilization,and a specific Gradient-index transmission can be designed.The mirror aligns the laser diode beam.In this paper,a system for generating linear structured light is designed for a blue single-tube semiconductor laser.The system consists of three parts:a single-tube Gradient-index lens or a triple-Gradient-index lens group for generating parallel or far-focusing beams,a cylindrical lens for generating linear structured light and a volume Bragg grating for reducing beam width and filtering out stray light.In this paper,the boundary conditions such as the numerical aperture and length of the Gradient-index lens,the wavelength and angle selectivity of the volume Bragg grating are simulated.In this paper,a line structured light system is designed for a commercial Blu-ray diode with a fast-axis half-power angle of 23 degree.Finally,a line structured light output with a beam width of 0.48mm at 5.5m and less than 0.60mm in the range of 5.5+0.5m is obtained.The result is better than that of traditional commercial line structured light products.Therefore,this system provides a new idea for the selection of line structured light measurement scheme.It is found that the Bragg grating filters most of the stray light and the beam with large angle deviation.The factor that restricts the further narrowing of the beam width should be the ion exchange technology of the Gradient-index lens.When the Gradient-index lens which is closer to the ideal refractive index distribution curve is exchanged,the beam width of the line-structured light system will be smaller.