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EP-4628874-B1 - FLUORESCENCE IMAGING OF GEMSTONE ON TRANSPARENT STAGE

EP4628874B1EP 4628874 B1EP4628874 B1EP 4628874B1EP-4628874-B1

Inventors

  • TSAI, TSUNG-HAN
  • WANG, WUYI

Dates

Publication Date
20260513
Application Date
20201125

Claims (15)

  1. A method of analyzing gemstones, the method comprising: supporting a gemstone (206, 306) on a flat stage (208), wherein the stage is capable of transmitting UV to visible light, and wherein the gemstone is backed by an absorption material; causing a light beam (210) to emit from a light source (202), the light beam within a first range of wavelengths, aimed at a first dichroic beam splitter (230) toward the flat stage, wherein the first dichroic beam splitter is configured to reflect light of the first range of wavelengths and pass light of a second range of wavelengths; and capturing a fluorescence image of the gemstone on the flat stage by a digital camera (242) aimed at a second dichroic beam splitter configured to reflect light of the second range of wavelengths that pass through the first dichroic beam splitter.
  2. The method of claim 1 wherein the UV transmitting stage is made of sapphire.
  3. The method of claim 1 wherein the UV transmitting stage is made of quartz.
  4. The method of claim 1 wherein the gemstone is arranged table side down (278) on the stage.
  5. The method of claim 1 wherein the light source is at least one of, a xenon flash lamp, a deuterium lamp, and a 224.3 nm HeAg laser.
  6. The method of claim 1 wherein the light beam is sent through a lens (204) to concentrate the beam.
  7. The method of claim 1 wherein the light beam is sent through a deep UV filter (205).
  8. The method of claim 1 wherein the light beam is sent through a polarizer (207).
  9. The method of claim 1 wherein the first range of wavelengths is between 10 nm and 400 nm.
  10. The method of claim 1 wherein the second range of wavelengths is between 400 nm and 700 nm.
  11. The method of claim 1 wherein the digital camera is a light sensitive digital color camera.
  12. The method of claim 1 wherein the digital camera is a monochrome camera.
  13. The method of claim 1 wherein the digital camera includes a lens (240) configured to concentrate the light of the second range of wavelengths.
  14. The method of claim 1 wherein the digital camera includes a filter (241) comprising at least one of, a long pass filter, a band-pass filter, a short-pass filter, and a polarization sensitive filter.
  15. The method of claim 1 wherein the first dichroic beam splitter is arranged to reflect the light beam at a perpendicular angle to the flat table.

Description

Field The field includes utilizing fluorescence image capture for analyzing a diamond or other gemstone positioned on a stage. Background The need for a systematic and easily reproducible analyzing method is needed for gemstones. Current technologies rely on aiming illumination into a diamond or stones pavilion. This method requires cumbersome aiming of the illumination source on a part of a stone which may be different depending on the stones size and shape. The method may not be easily reproduced or replicated due to aiming constraints and parameters. Further, using this method, additional hardware may be necessary to aim, adjust, or focus an imaging or illumination source on a gemstone. That is because auto-focusing on a gemstone is difficult. Polished gem facets are difficult to auto-focus on because the surfaces are lacking definable and identifiable features for the camera and software to analyze and focus. Other example systems utilize gemstone holders that are needed to position the gemstone under evaluation at a particular angle, and hold it there while imaged. Other example systems utilize components that require spread out components which are not capable of being configured into a compact unit. Example prior art systems are described in US 6,014,208 A, WO 2019/185993 A1, US 5,883,389 A, US 9,958,398 B2 and EP 3,505,916 A1. The systems and methods here provide for technical solutions to this technical problem using an easily reproducible setup that allows a user to place and analyze a stone with minimal adjustments, from stone-to-stone. Summary Systems and methods here may be used to provide a method to analyze a gemstone, specifically fluorescence image, such as a diamond, in an easily reproducible arrangement that minimizes adjustments between target stones and yet produces reliable results. In some examples, alternatively or additionally, systems and methods of capturing and analyzing fluoresce images of a sample gemstone, include generating a fluorescence exciting beam, 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, receiving, at a camera with a computer processor and a memory, an excited fluorescence image from the sample gemstone resting table-side down on a sapphire stage, wherein the excited fluorescence image having passed through the dichroic beam splitter, digitizing, by the camera computer, the received fluorescence image of the sample gemstone, and sending, by the camera computer, the digitized image of the sample gemstone table to a computer data storage. In some examples, alternatively or additionally, further comprising, by a back end computer with a processor and a memory, comparing a second digitized image to the stored digitized image and determining a match for identification. In some examples, alternatively or additionally, further comprising, analyzing, by a back end computer with a processor and a memory, the stored digitized image for determination of whether the sample gemstone is a natural or synthetic diamond. In some examples, alternatively or additionally, the directed, filtered beam has a wavelength of between 200 nm and 250 nm. In some examples, alternatively or additionally, the directed, filtered beam has a wavelength of about 224 nm. In some examples, alternatively or additionally, the generating of a fluorescence beam is by a Xe flash lamp. In some examples, alternatively or additionally, the excited fluorescence image from the sample gemstone resting table-side down on a sapphire stage has a wavelength between 400 nm and 700 nm. In some examples, alternatively or additionally, the comparing of the second digitized image to the stored digitized image and determining a match for identification is a comparison of a subset of pixels in the full digitized images. In some examples, alternatively or additionally, the excited fluorescence image from the sample gemstone resting table-side down on a sapphire stage, is also reflected off a mirror before being received at the camera and after passing through the dichroic beam splitter. In some examples, alternatively or additionally, the dichroic beam splitter is configured to reflect wavelengths less than 300 nm and pass wavelengths greater than 300 nm. In some examples, alternatively or additionally, the filter through which the fluorescence exciting beam is filtered includes a polarization sensitive filter. Systems and methods here may include analyzing fluoresce images of a sample gemstone, including a light generator for creating a beam capable of exciting fluorescence in a gemstone, a dichroic beam splitter, configured to reflect wavelengths from the light generator and pass wavelengths from fluorescence excitation of the sample gemstone, wherein a lens and a filter are configured to focus and filter