Pattern Drawing Device Anisotropic Refractive Power Aberration Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing beam scanning apparatuses face challenges in maintaining a constant image position due to tilting errors in polygon mirrors, leading to shifts in the beam projection and increased optical aberrations, especially when drawing finer patterns.
Innovation Solution
A pattern drawing apparatus with a first optical system causing anisotropic refractive power for beam convergence in the sub scanning direction, combined with a scanning optical system and a second optical system with anisotropic refractive power, where the focal distance of the second system is set to minimize sagittal coma aberration within the Airy disk radius, ensuring stable and precise pattern drawing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the spot light size is reduced to draw finer patterns, then the pattern fineness is improved, but the optical aberrations (coma, focus error, spherical aberration) increase and exceed the acceptable range
Solution Approach 1:
The optical system is divided into three distinct segments: a first optical system before the polygon mirror, a scanning optical system, and a second optical system after the scanning optical system. Each segment has specific refractive power characteristics that work together to control aberrations while enabling fine pattern drawing. The first and second optical systems specifically address sagittal coma aberration, allowing the spot light to be sufficiently small for fine patterns while keeping aberrations within acceptable ranges.
Solution Approach 2:
The patent applies anisotropic refractive power locally at specific positions in the optical path. The first optical system has refractive power in a direction orthogonal to the polygon mirror rotation direction, and the second optical system has refractive power in the main scanning direction. This localized application of refractive power corrects aberrations at critical points in the optical path without affecting the overall scanning function, enabling fine pattern drawing with controlled aberrations.
2Stability of the object's composition
If cylindrical lenses are added to correct tilting errors and maintain constant image position, then the image position stability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the functions of tilting error correction and aberration control into a unified optical system. The first and second optical systems with anisotropic refractive power simultaneously correct tilting errors caused by polygon mirror inaccuracies and control sagittal coma aberration. This integration achieves image position stability while managing aberrations without requiring separate correction mechanisms, thereby limiting the increase in device complexity.
3Manufacturing precision
If the refractive power is increased to reduce beam size for finer patterns, then the pattern resolution is improved, but the optical aberrations increase beyond acceptable limits
Solution Approach 1:
The patent carefully controls the refractive power parameters of the first and second optical systems. The refractive power is set to specific ranges that enable sufficient beam convergence for fine pattern drawing while keeping sagittal coma aberration within acceptable limits. The focal distances and refractive power values are optimized to achieve the desired pattern resolution without excessive aberration increase.
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 solution effectively prevents positional shifts and reduces aberrations, enabling the drawing of finer patterns with improved imaging performance and resolution across the scanning range.
Implementation Method 1
a first optical system configured to receive the beam from the light source apparatus and having anisotropic refractive power causing the beam heading toward a reflective surface of the deflective member to converge in a sub scanning direction
Implementation Method 2
a scanning optical system configured to receive the beam deflected by the reflective surface of the deflective member and condense the beam as the spot on the object to be irradiated
Implementation Method 3
a second optical system that has anisotropic refractive power causing the beam emitted from the scanning optical system and heading toward the object to be irradiated to converge in the sub scanning direction
Data Source
AI summary
A pattern drawing device is provided with: a first cylindrical lens on which a beam from a light source device is incident and which has an anisotropic refractive power for converging, in a sub-scanning direction orthogonal to a main scanning direction, the beam traveling toward a reflection surface of a polygon mirror; an fθ lens system for causing the beam having been deflected by the reflection surface of the polygon mirror to be incident thereon, and for condensing the beam as a spot light on a surface of an object to be irradiated; and a second cylindrical lens having an anisotropic refractive power for converging, in the sub-scanning direction, the beam traveling toward the surface after being emitted from the fθ lens system.