Gemstone Fluorescence Imaging With a Dichroic Beam Splitter
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Solution Overview
Problem
Current gemstone analysis methods are cumbersome and difficult to reproduce due to the need for precise aiming of illumination sources, which is challenging for polished gem facets lacking definable features, and often require additional hardware and complex setups.
Innovation Solution
A fluorescence imaging system utilizing a dichroic beam splitter and a flat stage to capture gemstone images, allowing for easy placement of gemstones table-side down, with a focused interface for consistent imaging without adjustments, using a xenon flash lamp or similar light sources to excite fluorescence, and a camera to digitize and analyze the images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional illumination aiming methods are used, then gemstone analysis can be performed, but the setup becomes complex and difficult to reproduce
Solution Approach 1:
The system separates the illumination and imaging functions by using a fluorescence microscope setup where the excitation light path and fluorescence collection path are distinct. The dichroic beam splitter divides the optical path, allowing independent optimization of illumination aiming and image capture, thereby simplifying the overall setup and improving reproducibility.
Solution Approach 2:
A dichroic beam splitter is introduced as an intermediary optical element that selectively transmits excitation light while reflecting fluorescence light. This mediator enables the system to handle different wavelengths separately, simplifying the optical path configuration and eliminating the need for complex aiming adjustments.
2Extent of automation
If auto-focusing is attempted on polished gem facets, then imaging can be automated, but the polished surfaces lack definable features for focusing
Solution Approach 1:
Instead of attempting to focus directly on the polished gemstone surface which lacks definable features, the system focuses on the fluorescence image formed on the camera sensor. The fluorescence emission provides contrast and detail that enables automatic focus detection, effectively copying the focusing task from the physical surface to the optical image.
Solution Approach 2:
The system exploits the fluorescence color change phenomenon where the gemstone absorbs excitation light and emits fluorescence at different wavelengths. This color/ wavelength transformation provides the contrast necessary for automatic focus detection, as the fluorescence signal varies with focus position unlike the polished surface reflections.
3Manufacturing precision
If gemstone holders are used to position stones at particular angles, then consistent imaging is achieved, but the setup requires additional hardware
Solution Approach 1:
The fluorescence microscope setup serves multiple functions: it provides illumination, separates excitation and fluorescence light paths, captures images, and enables focusing - all within a single integrated system. This multi-functionality eliminates the need for separate gemstone holders and positioning hardware, achieving consistent imaging without additional components.
4Adaptability or versatility
If components are spread out to enable analysis, then analysis capability is achieved, but the system cannot be configured into a compact unit
Solution Approach 1:
The optical components are nested within each other in a compact fluorescence microscope configuration. The dichroic beam splitter is positioned to allow the excitation light path to pass through it, with the fluorescence collection path nested within the same spatial envelope. This nesting enables the entire analysis system to be configured into a compact unit while maintaining full analysis capability.
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 reproducible and efficient analysis of gemstones with minimal adjustments, facilitating quick sample swapping and reliable identification of natural vs. synthetic diamonds and detection of synthetic overgrowth.
Implementation Method 1
directing the fluorescence exciting beam through a filter and to a dichroic beam splitter, wherein the dichroic beam splitter is configured to reflect wavelengths of the fluorescence exciting beam and pass wavelengths of excited fluorescence from the sample gemstone
Implementation Method 2
generating a fluorescence exciting beam... the generating of a fluorescence beam is by a Xe flash lamp... the directed, filtered beam has a wavelength of between 200 nm and 250 nm
Implementation Method 3
receiving, at a camera with a computer processor and a memory, an excited fluorescence image from the sample gemstone... digitizing, by the camera computer, the received fluorescence image
Data Source
AI summary
Systems and methods here may be used for a setup of fluorescence image capturing of a gemstone, such as a diamond placed on a flat stage. Some examples utilize a setup that both sends light and captures the image from the table side of the gemstone by passing ultraviolet (UV) light between 10 nm and 400 nm to the gemstone and capturing the excited fluorescence image for analysis through a dichroic beam splitter. In some examples, the cutoff is 300 nm. The dichroic beam splitter arrangement allows for the camera to focus on the same interface of the stage and gemstone over and over for ease of use and without moving, changing, or adjusting the equipment for different samples.