Dark Field Illumination for Droplet Dispenser Nozzle Imaging
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Solution Overview
Problem
Conventional imaging techniques for nozzle sections of droplet dispenser devices suffer from inhomogeneous sample illumination and light collection, leading to reduced precision and reliability in detecting particles, poor optical contrast, and restricted nozzle movement.
Innovation Solution
An imaging apparatus utilizing dark field illumination, where the illumination axis and imaging axis are slanted relative to each other, allowing for improved light scattering from particles within the nozzle section, resulting in high contrast imaging with a dark background.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If bright field illumination is used with the nozzle section, then the illumination setup is simple, but the sample illumination becomes highly inhomogeneous and light collection is inhomogeneous, reducing detection precision
Solution Approach 1:
The patent changes the illumination parameters by switching from bright field to dark field illumination geometry, where the illumination axis and imaging axis are slanted relative to each other. This parameter change transforms the light scattering characteristics, causing particles to appear bright against a dark background, thereby improving detection precision without significantly increasing device complexity
Solution Approach 2:
The patent converts the harmful effect of light scattering by the nozzle walls (which causes inhomogeneous illumination in bright field) into a beneficial effect. By using dark field illumination geometry, the scattered light from the nozzle walls is directed away from the imaging axis, while light scattered by particles is collected, transforming the previously harmful scattering into a useful signal enhancement mechanism
2Measurement precision
If the camera is positioned closer to the nozzle section to increase the central bright area, then more particles can be detected, but the depth of field is reduced, limiting sharp imaging to only a specific plane
Solution Approach 1:
The patent changes the illumination geometry parameter to dark field configuration, which allows for a larger acceptance angle of scattered light. This parameter change enables the camera to collect light from particles at different depths within the nozzle section, effectively increasing the depth of field and allowing sharp imaging across a larger volume without requiring the camera to be positioned closer to the nozzle
3Measurement precision
If dark field illumination with slanted axes is implemented, then particle detection contrast is improved with dark background, but the illumination and imaging paths become more complex
Solution Approach 1:
The patent applies asymmetry by deliberately slanting the illumination axis relative to the imaging axis in a dark field configuration. This asymmetric arrangement causes light scattered by particles to be directed toward the camera while direct illumination and wall-scattered light are directed away, creating high contrast images with dark backgrounds. The asymmetric geometry achieves superior particle detection contrast without requiring complex additional optical components
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 dark field imaging technique enhances the detection of particles by providing high contrast images with reduced background noise, allowing for precise detection of sub-micron particles and maintaining full nozzle movability.
Implementation Method 1
dark field illumination of the nozzle section, wherein, in particular at an intersection of the illumination axis and the imaging axis at the nozzle section, the illumination axis and the imaging axis are slanted (or: inclined, arranged at an angle) relative to each other and an illumination angle between the illumination axis and the imaging axis is selected such that the at least one nozzle image is collected with a dark background
Data Source
AI summary
Imaging apparatus 10 for imaging nozzle section 21 of droplet dispenser device 20 includes illumination device 11 arranged for creating illumination light directed along illumination axis A1 towards an illumination range configured for accommodating nozzle section 21, and camera device 12 having imaging axis A2 directed to the illumination range. Camera device 12 is configured for collecting nozzle image(s) of nozzle section 21 arranged in the illumination range, wherein illumination device 11 and camera device 12 are arranged for dark field illumination of nozzle section 21. Illumination axis A1 and imaging axis A2 are slanted relative to each other and an illumination angle between axes A1 and A2 is selected such that the at least one nozzle image is collected with a dark background. Furthermore, dispenser apparatus 100 for dispensing droplets on a target and an imaging method for imaging nozzle section 21 of droplet dispenser device 20 are described.