4 Methods for Generating Linear Light Spots
A straight line light spot refers to a straight line light spot generated by laser passing through different optical elements. It is often widely used in precise positioning, marking and measurement tasks. Next, we will introduce the generation method, application and feature comparison of the straight line light spot.
Method for Generating Linear Light Spots
Used to obtain a linear light spot with strong energy in the center and weak energy on both sides
The cylindrical lens has a flat surface on one side and a cylindrical surface on the other side. Unlike a spherical lens, a cylindrical lens only acts on the light beam in one direction. It is used in applications that require simple shaping of a point light source in one-dimensional direction, and can convert a collimated laser beam into a linear beam. However, when a Gaussian light spot is incident, its linear light spot energy distribution is strong in the center and weak on both sides. The flat cylindrical lens has a planar structure and a spherical aberration-free characteristic. All light rays passing through the effective aperture are diffracted at different periodic positions on the x-axis, so that the light rays on the same x-axis line can converge to the same position. Finally, the focused light spot forms a vertical line perpendicular to the x-axis, and the length is consistent with the original light spot diameter.
Borisun Optics provides uncoated and anti-reflection coated N-BK7 cylindrical lenses in different wavelength ranges, as well as flat cylindrical lenses based on LCP/N-BK7 windows, which can be selected for a variety of applications.
01 Powell Prism is used to Obtain Linear Light Spots with Relatively Uniform Energy
Powell prism is also called laser linear emission lens. It can fan out the collimated light beam into a one-dimensional laser straight line. Its top is an aspherical surface. Through the precise control of the curvature of the lens surface, the spherical aberration is greatly increased, the light intensity in the central area is reduced, and the light intensity at both ends of the linear light spot is increased, so that the light intensity of the collimated incident Gaussian light can be evenly distributed after passing through the Powell prism. Compared with the cylindrical lens, it can produce linear light spots with relatively uniform energy, eliminating the central hot spot and faded edge distribution of the Gaussian beam. However, since the Powell prism is precisely designed for the parameters of the incident light spot, it has relatively strict requirements on the parameters of the incident light spot, which needs to be highly matched with the design parameters. If the size of the incident light spot is too large or too small, the energy of the straight-line light spot after shaping will be uneven. Its advantage is that uniform linear light spots can be obtained at different working distances, and because the divergence angle is fixed, the length of the linear light spot changes with the working distance.
Borisun Optics Powell prism is made of N-BK7 material, which can make the Ø0.8mm (1/e^2) 633nm collimated incident Gaussian light pass through the Powell prism to evenly distribute the light intensity. Within the 80% range of the laser line symmetry, the non-uniformity is less than 30%. It is suitable for various biomedical, automotive assembly, line scanning confocal microscopy and other machine vision applications.
02 Cylindrical Lens Array/Flat Cylindrical Lens Array
Used to obtain linear light spots with higher precision
Cylindrical lens arrays are composed of cylindrical lenses with the same spacing. Compared with traditional cylindrical lenses, they can achieve linear light spots while making the light source energy uniform along the expansion direction. When used with a lens, a sharp-edged homogenized linear light spot can be obtained by first differentiating and then integrating.
The flat cylindrical lens array is a flat optical element based on the diffraction optical principle of liquid crystal polymer to achieve one-dimensional shaping and homogenization of the light beam. The cylindrical lens array function is achieved by the one-dimensional array phase distribution on the polymer film. The device is a single-wavelength design, without spherical aberration, and the flat structure is easy to integrate.
The advantage of the flat cylindrical lens array is that its adaptive spot size can be flexibly adjusted according to system requirements, and its linear spot length and working distance can also be adjusted by changing the focal length of the matching lens. It has great application potential in the fields of imaging, machine vision, and semiconductor laser collimation. Borisun Optics has flat cylindrical lens arrays based on liquid crystal polymer/N-BK7 substrates of different specifications, and can also provide flexible customization services.
03 Linear Homogenization DOE
Used to generate high-energy linear light spots on the focal plane
Linear homogenization DOE needs to cooperate with the focusing module to produce a linear light spot on its focal plane, use the point-to-point mapping method to calculate the designed phase, and then use the LCP film to introduce the designed geometric phase distribution to achieve the shaping and homogenization of the Gaussian incident light. Therefore, it has strict requirements on the beam quality, spot size and other parameters of the incident light spot. The linear light spot length obtained by the linear homogenization DOE on the focal plane is generally in the order of tens of microns to several millimeters, and the width is the diffraction limit, which is usually used in laser processing scenarios. In addition to providing 1064nm and 532nm wavelengths, Borisun Optics linear homogenization DOE also supports flexible customization of parameter specifications.
Application of Linear Light Spot
Rectangular Beam Shaping
In similar application scenarios such as laser radar and 3D sensing, when a uniform rectangular light spot is required as the emitted light, a double-plate cylindrical lens array can be used for beam shaping and homogenization. The double-plate cylindrical lens grid lines are placed perpendicular to each other, and the ratio of the length and width of the rectangle can be flexibly controlled by adjusting the parameters of each of them.
Machine Vision Tasks
Line lasers play an important role in machine vision tasks and can be used for precise measurement and positioning. By projecting a linear beam, the size, shape and position of an object can be measured. In addition, line lasers can also detect the contours and edges of objects. By comparing the deformation of the laser on the object, the contour concave information of the object can be obtained to determine its shape and defect location. This technology is widely used in automated production.
LiDAR Obstacle Avoidance
Line lasers can be used for obstacle avoidance tasks in the LiDAR systems of robots and sweepers. By projecting a straight line beam of light around, the robot can use the reflection and deformation of light to determine the obstacles around itself, thereby achieving precise obstacle avoidance.
Online Scanning OCT
In online scanning OCT, a linear spot is focused into a thin line by an optical element and moves along the surface of the sample during scanning. When the light intersects with different structures in the sample, part of the light is reflected or scattered back to form an interference signal. By analyzing the intensity and phase of these interference signals, the structural information inside the sample can be reconstructed.
Online Scanning Confocal Microscope
In online scanning confocal microscopy, by using a linear spot, the spot is scanned along the surface of the sample, thereby achieving rapid imaging of the sample surface and high-resolution three-dimensional structure reconstruction, which can greatly improve the scanning efficiency. When the linear spot moves on the sample surface, the area where it intersects with the sample will generate a confocal imaging signal. By detecting the intensity and phase of these confocal signals, the system can determine the height and morphological information of each point on the sample surface. By continuously moving the linear spot and recording the confocal imaging signal at each position, a three-dimensional structural model of the sample can be constructed.
Comparison of Features of Different Solutions
| Product Name | Wavelength Requirements | Light Spot Size Requirements | Linear Uniformity | Polarization Related |
|---|---|---|---|---|
| Cylindrical lens | none | none | low | no |
| Flat Cylindrical Lens | Single wavelength device | none | low | yes |
| Powell Prism | Single wavelength device | strict | ＞70% | no |
| Lens Array | None | None | ＞90% | no |
| Flat Cylindrical Lens Array | Single wavelength device | none | ＞90% | yes |
In summary, linear light spots are not only diverse and flexible in generation methods, but also show great potential in applications in the fields of industrial detection and positioning, lidar, 3D sensing, medical imaging, machine vision, etc. We can expect linear light spots to be used in a wider range of fields, bringing more innovation and progress to mankind.
ABOUT BORISUN
Hanzhong Brisun Optics Co., Ltd. Is the high precision optical element manufacturer provides customized production of Various optical lenses, including spherical lens, cylindrical lens, optical window, mirror, prism, filter, metal base mirror and other high-precision optical elements. The base materials include various optical glass, fused quartz, calcium fluoride (CaF2), zinc selenide (ZnSe), germanium (GE), silicon (SI), sapphire, metal and other materials. And provide antireflective film, high reflection film, spectroscopic film, metal film and other optical coatings.
Welcome to OEM and Purchasing!
Recent Posts
Send Requests