Three-Lens F-Theta Objective for Compact Scanning
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Solution Overview
Problem
Existing F-theta objectives for scanner applications often require a larger number of lenses to achieve a large scanning field, which can lead to increased complexity and size, making them less compact and efficient.
Innovation Solution
A compact F-theta objective design utilizing precisely three lenses, comprising a biconvex lens with positive refractive power, a biconcave lens with negative refractive power, and a meniscus lens with positive refractive power, arranged in a specific configuration to achieve a large scanning field while maintaining a compact form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a larger number of lenses are used in F-theta objectives, then the scanning field coverage is improved, but the device complexity and size increase
Solution Approach 1:
The patent changes the optical parameters by using lenses with high refractive indices (1.7-1.9) and specific curvature radii to achieve a large scanning field with only three lenses. The first lens has curvature radii of 50-150mm and the second lens has curvature radii of 30-100mm, optimized to cover a scanning field of 100x100mm to 200x200mm while maintaining compactness
Solution Approach 2:
The patent employs composite optical design combining a biconvex first lens, biconcave second lens, and meniscus third lens with specific refractive indices (1.7-1.9) to achieve the desired scanning field. This composite lens structure optimizes the balance between scanning field coverage and device compactness
2Area of stationary object
If more lenses are used to achieve large scanning field, then the scanning field is improved, but the overall length and compactness deteriorate
Solution Approach 1:
The patent optimizes the focal lengths and curvature radii parameters to achieve compactness. The first lens has focal length 50-150mm, the second lens has focal length -30 to -100mm, and the third lens has focal length 50-150mm, resulting in an overall length of 100-300mm that maintains compactness while providing large scanning field coverage
3Length of stationary object
If the lens diameter is reduced for compactness, then the device size is improved, but the radial illumination on subsequent lenses increases
Solution Approach 1:
The patent uses lenses with high refractive indices (1.7-1.9) and optimized curvature radii to reduce the required lens diameters. The first lens has curvature radii of 50-150mm and the second lens has curvature radii of 30-100mm, which reduces radial illumination on subsequent lenses while maintaining compact device size
Solution Approach 2:
The composite lens structure with specific refractive indices (1.7-1.9) optimizes the light distribution to reduce radial illumination. The combination of biconvex, biconcave, and meniscus lenses with optimized parameters minimizes the diameter required while controlling illumination patterns
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The three-lens configuration enables a large scanning field with a significantly compact design, reducing radial illumination on subsequent lenses and allowing for smaller lens diameters, thus enhancing mechanical compatibility and achieving a diffraction-limited image.
Implementation Method 1
a first lens with a first focal length, which is designed as a biconvex lens with a positive refractive power
Implementation Method 2
for focusing the laser beam in a focal plane
Implementation Method 3
a second lens with a second focal length, which is designed as a biconcave lens with a negative refractive power
Implementation Method 4
a third lens with a third focal length, which is designed as a meniscus lens with a positive refractive power
Implementation Method 5
achieving a diffraction-limited image
Data Source
AI summary
An F-theta objective has precisely three lenses. The three lenses being: a first lens with a first focal length, which is designed as a biconvex lens with a positive refractive power, a second lens with a second focal length, which is designed as a biconcave lens with a negative refractive power, and a third lens with a third focal length, which is designed as a meniscus lens with a positive refractive power. The first lens, the second lens, and the third lens are arranged one behind the other in a beam path and form a lens assembly.