Laser Spot Projection Optics for Reduced Diffraction Edges
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional barcode readers with LED-based spot indicators suffer from limited visibility range and diffraction effects, making it difficult to project a clear and bright spot indicator beyond 1 meter due to physical constraints and inefficiencies in the optical projection system.
Innovation Solution
An optical system utilizing a laser diode as a coherent light source, positioning the object plane between the emission point and the aperture, and using an imaging lens to focus the coherent light onto an image plane, effectively reducing diffraction patterns and increasing brightness at longer ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an LED light source is used to project a spot indicator, then the device can be miniaturized and operate in silent mode, but the brightness is weak at distances greater than 1 meter making the spot indicator difficult or impossible to see
Solution Approach 1:
The patent changes the fundamental parameter of light coherence by replacing the LED light source with a laser diode. This parameter change transforms the light from incoherent to coherent, enabling the light to maintain its intensity over longer distances and resolve the contradiction between brightness and visibility range.
2Illumination intensity
If the dimension of the spot is reduced to increase brightness at longer ranges, then the spot becomes brighter, but the spot indicator becomes difficult or impossible to see due to reduced size
Solution Approach 1:
The patent changes the coherence parameter of the light source, which fundamentally alters how the light propagates and maintains its properties. Coherent light from the laser diode can be focused more tightly and maintain its intensity over distance without requiring the spot area to be reduced, thus resolving the contradiction between brightness and spot area.
3Illumination intensity
If a laser diode is used as a light source, then the spot indicator becomes significantly brighter at longer ranges, but diffraction patterns are produced that make the projected circle look like a blob or non-circular shape
Solution Approach 1:
The patent introduces an intermediary optical element (lens or lens system) between the laser diode and the target surface. This intermediary component focuses the coherent light and corrects the diffraction patterns, maintaining both the brightness advantage of laser light and the desired circular shape of the spot indicator.
4Length of stationary object
If the focal length of the lens is enlarged to increase visibility range, then the spot indicator can be seen at longer distances, but the physical size of the barcode reader increases
Solution Approach 1:
The patent changes the light coherence parameter from incoherent (LED) to coherent (laser diode), which fundamentally alters the optical propagation characteristics. Coherent light can achieve longer visibility ranges with shorter focal length lenses, thus resolving the contradiction between visibility range and device size.
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 enables a brighter and aesthetically pleasing spot indicator visible up to 20 meters with sharp edges, overcoming the limitations of conventional systems by optimizing the distance between the laser, aperture, and imaging lens configurations.
Implementation Method 1
Laser diodes produce coherent light emitted in a narrow emission angle
Implementation Method 2
An imaging lens is disposed in optical alignment with the aperture defined by the structure. The imaging lens is configured to focus the coherent light onto an image plane
Implementation Method 3
An imaging lens may be disposed in optical alignment with the aperture defined by the structure. The imaging lens may be configured to focus the coherent light onto an image plane located at a second distance from the imaging lens.
Implementation Method 4
the use of the green spot indicator allows for silent mode operation... an optical system that images a cross-section of a light cone defined by a divergence angle of a laser beam produced by a laser diode or other coherent light source and subtended by a circular aperture
Data Source
AI summary
A system and method for projecting coherent light with reduced diffraction pattern may include a coherent illumination source, structure with an aperture, and focusing lens. The focusing lens may have an object plane defined between the illumination source and structure, such that an illumination signal, such as an indication signal (e.g., green spot, aiming signal, etc.) that is projected through the aperture and onto an image plane does not exhibit a noticeable diffraction pattern, thereby having sharper edges and more perceptible to a user of a system that performs the projection of coherent light. The focusing lens may be in front of, at, integrated with, or behind the structure with the aperture, but the object plane remains between the coherent illumination source and structure with the aperture.