Case Study: Custom Powell Lenses with a 30° Fan Angle

Powell lenses are specialized optics designed to transform laser beams into evenly illuminated lines, playing a critical role in various high-precision applications such as laser communication, medical equipment, and precision measurement systems. These lenses distribute light more uniformly than traditional cylindrical lenses, which often produce lines with bright central spots and uneven edges. The focus of this project is a custom-designed Powell lens featuring a 30° fan angle, optimized for a 2.5mm input beam diameter and wavelengths within the visible light spectrum.

How Powell Lenses Work

Unlike other lenses, Powell lenses have a unique prism-like structure with a rounded roof. This design allows them to convert a collimated, narrow laser beam into a straight line with uniform energy distribution. Cylindrical lenses tend to produce lines with fading edges and a bright center, but Powell lenses ensure the light spreads evenly, providing more consistent results across the entire line.

Core Design Factors for Powell Lenses

The design of a Powell lens is shaped by two key factors:

Fan Angle: The fan angle is the angle at which the laser beam spreads when it passes through the lens. A larger fan angle results in a longer laser line at a given distance. In this case, the lens is designed with a 30° fan angle, which is optimal for producing a well-defined, straight line of light over a specific distance.
Incident Spot Size: The incident spot size refers to the diameter of the laser beam as it enters the lens, usually measured when the energy intensity drops to 1/e² of the peak. Matching the incident spot size to the lens is essential for maintaining even light distribution. If the spot size doesn’t align with the lens, the energy distribution of the output beam can be uneven.

Fan Angle of Powell Prism

Detailed Specifications for the 30° Fan Angle Powell Lens

Fan Angle: 30°
Input Beam Diameter: 2.5mm
Wavelength Range: 400-700nm (visible light spectrum)

This specific lens is made from a material with a low refractive index, which enhances the uniformity of the light spot. The uniformity across the beam is excellent, with a variance of less than 10% over 80% of the beam’s coverage.

Factors to Consider in Powell Lens Design

When designing a Powell lens for any application, several factors must be evaluated:

Laser Wavelength: The lens must be tailored to the specific wavelength of the laser used.
Line Width: The required width of the laser line needs to be considered for the application.
Line Length: The necessary length of the laser line at a certain distance must also be factored in.
Working Distance: This refers to the distance from the lens to the target surface and impacts the final laser line quality.
Beam Quality: The desired quality of the output laser beam is another important design consideration, as it can affect the performance in the application.

Custom Powell lenses, such as this 30° fan angle model, are essential for generating uniform laser lines in demanding applications. This particular design, optimized for a 2.5mm input beam and visible light wavelengths, showcases how crucial the fan angle and incident spot size are to achieving the desired performance. The lens’s low refractive index material ensures superior spot uniformity, making it ideal for a range of industrial and research uses.

Contact Shanghai Optics today! We’d be more than happy to discuss your projects and how to best bring them to fruition.