Fold Mirror Optical Path Redirection for Imaging Workstations
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Solution Overview
Problem
Existing electro-optical workstations face issues with specular reflections and virtual images caused by illumination light and IR light reflecting off the window, leading to 'hot spots' that saturate and blind the image sensor, degrading reading performance, especially at farther working distances.
Innovation Solution
A fold mirror is mounted between the window and the imaging module, oriented in a plane parallel to the window to prevent reflections from entering the imaging field of view, ensuring that all reflections are moved outside the captured image, thereby enhancing reading performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If illumination light assembly and object sensing assembly are provided inside the housing, then the amount of return light captured by the sensor array is increased, but specular reflections and virtual images are created that saturate and blind the image sensor
Solution Approach 1:
A fold mirror is introduced as an intermediary optical element between the illumination light assembly and the image sensor. The fold mirror redirects the illumination light path at an angle, causing it to illuminate the target from a different direction and preventing direct reflection back into the image sensor's field of view. This mediator successfully separates the illumination function from the harmful reflection path.
2Reliability
If the upright window is positioned to capture targets at far range, then reading capability at distant distances is improved, but hot spots from reflected light enter the imaging field of view
Solution Approach 1:
The fold mirror is positioned and oriented asymmetrically relative to the window and imaging module. Specifically, the fold mirror is angled at approximately 45 degrees to redirect light paths. This asymmetric configuration ensures that the illumination light is reflected away from the image sensor's field of view while maintaining the window's ability to capture targets at various distances, including far range.
3Adaptability or versatility
If multiple illumination LEDs are positioned close to the upright window, then the illumination field of view covers the imaging field of view, but the total illumination becomes bothersome and distracting
Solution Approach 1:
The fold mirror introduces a new spatial dimension to the light path configuration. Instead of positioning LEDs only in the horizontal plane close to the window, the fold mirror redirects the light paths into a different spatial dimension (at approximately 45 degrees), allowing the LEDs to be positioned away from the window while still achieving full coverage of the imaging field of view. This eliminates the bothersome direct illumination from multiple close LEDs.
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 configuration effectively eliminates specular reflections and virtual images, preventing sensor overload and improving reading accuracy and reliability across a range of working distances.
Implementation Method 1
A fold mirror is mounted between the window and the imaging module, oriented in a plane parallel to the window to prevent reflections from entering the imaging field of view
Data Source
AI summary
A workstation electro-optically reads targets by image capture, and includes a housing, a generally planar window, an imaging module, and a generally planar fold mirror between the window and the module. The module has an illuminating light assembly for directing illumination light along an illumination path through the window at a target for return therefrom during reading, and an image sensing assembly for detecting return illumination light through the window along an imaging path over an imaging field of view during reading. The fold mirror folds the illumination and the imaging paths. The fold mirror and the window lie in planes that are substantially parallel to each other to prevent reflections of the illumination light off of the fold mirror and the window from entering the imaging field of view as virtual images that degrade target detection by the image sensing assembly.