Spatial Light Modulator Anamorphic Imaging for High-Speed Large-Area Printing

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Solution Overview

Problem

Current laser imaging systems face challenges in achieving high resolution and high power imaging across large areas in a single pass due to limitations in optical performance, such as image field curvature and differential aging of LED arrays, which restricts their application in high-speed printing and cutting processes.

Innovation Solution

A method utilizing a spatial light modulator with a homogenous light source and an anamorphic optical system to generate two or more substantially one-dimensional scan line image portions of a two-dimensional image simultaneously, allowing for high total optical intensity and efficient imaging across large areas without requiring high intensity light sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a single laser head motorized x-y flatbed architecture is used for large area coverage, then the imaging area is improved, but the imaging speed deteriorates and becomes too slow for high speed printing processes

Engineering Contradiction:
Improveimaging areaVSAvoidimaging speed
Core Design Contradiction:
Area of stationary objectVSProductivity

Solution Approach 1:

The patent divides the imaging system into multiple independent laser heads (first laser head and second laser head) that can simultaneously image different portions of the substrate. Each laser head operates independently to write scan lines, effectively segmenting the imaging task to achieve both large area coverage and high imaging speed without requiring sequential scanning.

Inventive Principle:
Principle #1Segmentation

2Productivity

If laser ROS sweeps perpendicular to process direction using polygon or galvo scanner, then imaging speed is improved, but image resolution deteriorates at extremes of scan line due to optical performance limitations

Engineering Contradiction:
Improveimaging speedVSAvoidimage resolution
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent transitions from single-direction scanning to two-dimensional parallel imaging by arranging laser heads in a configuration where they simultaneously write multiple scan lines across the substrate. This dimensional change allows the system to maintain high resolution across the entire imaging area by eliminating the need to sweep across long distances, thereby avoiding optical distortion at scan line extremes.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If two or more rows of staggered heads are used to extend LEDs to higher speeds or resolutions, then imaging resolution and speed are improved, but device complexity increases

Engineering Contradiction:
Improveimaging resolutionVSAvoidsystem complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the functionality of multiple laser heads and their associated scanning systems into a coordinated parallel operation. By synchronizing the operation of the first and second laser heads to simultaneously write adjacent scan lines, the system achieves high resolution and imaging speed while reducing overall complexity compared to sequential multi-row configurations, as the heads operate in unison rather than requiring complex staggered coordination.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables reliable, high-speed, high-resolution imaging with gray-scale capabilities and reduced laser speckle, facilitating applications like high-power overhead projection and maskless lithography by concentrating low-power light over a large number of modulating elements.

Implementation Method 1

configuring a spatial light modulator including a plurality of light modulating elements arranged in a plurality of rows and a plurality of columns in accordance with at least two scan line image data groups

Methodology Applied
Scientific EffectLight modulation:

Implementation Method 2

directing homogenous light onto the plurality of light modulating elements such that the configured first and second modulating element groups generate a modulated light field that is transmitted through an anamorphic optical system such that said modulated light field is anamorphically imaged and concentrated

Methodology Applied
Scientific EffectAnamorphic imaging:

Implementation Method 3

said modulated light field is anamorphically imaged and concentrated to form first and second substantially one-dimensional scan line images on said imaging surface

Methodology Applied
Scientific EffectOptical concentration: Focusing

Data Source

PatentEP2561997B1Multiple Line Single-Pass Imaging Using Spatial Light Modulator and Anamorphic Projection Optics
Publication Date: 2015.02.25 PALO ALTO RESEARCH CENTER INC
  • EP2561997B1 patent drawingFigure 1
  • EP2561997B1 patent drawingFigure 2(A)~2(B)
  • EP2561997B1 patent drawingFigure 2(C)~2(D)

AI summary

Two substantially one-dimensional scan line images are simultaneously generated by modulating a two-dimensional homogenous light field using a spatial light modulator (120) having light modulating elements (125) arranged in a plurality of rows and a plurality of columns. An upper group of modulating elements are configured using a first scan line image data group, and a lower group of modulating elements are configured using a second scan line image data group. The homogenous light source is then pulsed (toggled) to direct the two-dimensional homogenous light field onto the spatial light modulator. The resulting two-dimensional modulated light field is directed through an anamorphic optical system, which images and concentrates the modulated light on an imaging surface such that two parallel one-dimensional scan line images are simultaneously formed on the imaging surface.