Resin Diffractive Lens Optical Axis Shift for Returning Light Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical scanners using resin-made lenses and semiconductor lasers face challenges with environmental fluctuations, particularly temperature variations, causing changes in optical properties and beam spot diameter, leading to image density irregularities and color drift in multi-color image forming apparatuses due to unaccounted returning light and chromatic aberrations.
Innovation Solution
The optical scanner design includes a resin-made diffractive lens with a power in both main and vertical scanning directions, where at least one surface's optical axis is shifted or tilted in the main scanning cross-section to reduce returning light and beam displacement, effectively mitigating the effects of temperature variations and wavelength changes by offsetting diffracting and refracting powers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a resin-made lens is used in the optical scanner, then the weight, cost, and manufacturing ease are improved, but the optical properties and beam spot diameter change due to temperature variation
Solution Approach 1:
The patent applies parameter changes by designing the resin-made lens with specific aspherical surface parameters and refractive index characteristics that compensate for temperature-induced variations. The lens is designed with a focal length and curvature that counteract the thermal expansion and refractive index changes of the resin material, thereby maintaining stable optical properties across temperature ranges.
Solution Approach 2:
The patent employs composite material design by combining the resin-made lens with other optical elements (such as glass lenses or diffractive optical elements) in a hybrid optical system. This composite approach allows the system to leverage the manufacturing advantages of resin while compensating for its thermal sensitivity through the stable properties of other materials.
2Manufacturing precision
If the optical power of the resin-made lens is increased to improve focusing, then the beam spot diameter is reduced, but the sensitivity to temperature variation increases
Solution Approach 1:
The patent optimizes the parameter changes by carefully selecting the aspherical coefficient and refractive index of the resin material to achieve the desired beam spot diameter while minimizing temperature sensitivity. The lens design includes specific curvature radii and thickness profiles that balance focusing power with thermal stability.
Solution Approach 2:
The patent applies preliminary anti-action by pre-compensating for temperature-induced optical changes through the lens design. The lens is manufactured with specific aspherical parameters that create an opposite effect to thermal expansion, thereby counteracting temperature variations before they can degrade optical performance.
3Reliability
If a diffracting surface is added to correct optical properties, then the chromatic aberration is reduced, but the returning light to the semiconductor laser increases
Solution Approach 1:
The patent applies the taking out principle by extracting and removing the diffracting surface from the optical path between the semiconductor laser and the lens. Instead, the diffractive element is positioned after the lens, where it can correct optical properties without interfering with the laser beam path, thereby eliminating the returning light problem while maintaining optical correction benefits.
Solution Approach 2:
The patent uses an intermediary approach by introducing a beam splitter or directional coupler between the semiconductor laser and the diffractive element. This intermediary component directs the beam through the diffractive element in a way that prevents returning light from reaching the laser, while still allowing the diffractive element to perform its optical correction function.
4Reliability
If the optical system is designed to compensate for wavelength changes, then the chromatic aberration is reduced, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by designing the optical system with specific focal lengths and curvatures that are optimized for the semiconductor laser's operating wavelength. The lens parameters are selected to minimize chromatic aberration across the laser's wavelength range, thereby stabilizing optical properties without requiring complex compensation mechanisms.
Solution Approach 2:
The patent employs universality by designing the optical system to perform multiple functions: the resin-made lens simultaneously provides focusing, beam shaping, and chromatic aberration correction. This multi-functional design reduces the need for separate correction elements, thereby simplifying the overall device while maintaining wavelength stability.
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
This design reduces image density irregularities and color drift, enabling high-resolution image formation with minimized returning light to the semiconductor laser, thus stabilizing the optical properties and maintaining image quality across environmental changes.
Implementation Method 1
a resin-made diffractive lens that has a power in a main scanning direction and a vertical scanning direction
Implementation Method 2
resin-made diffractive lens
Implementation Method 3
an optical receiver that detects, before the optical beam scans the scanned surface, the optical beam
Implementation Method 4
A semiconductor laser as a common optical source of the optical scanner
Data Source
AI summary
An optical axis of at least one surface of a resin-made diffracting lens is shifted in a main scanning direction with respect to an incident beam. A synchronous detection can cancel a problem of a misalignment in the main scanning direction due to a temperature variation. A light reflected from a second surface of the resin-made diffractive lens condenses on a position that is displaced in an optical axis direction from an optical beam outgoing point of a semiconductor laser, and thereby the light reflected again from the semiconductor laser does not form an image on a scanned surface and an impact on the image becomes low.