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Patent Issued for Compensating Optical Coupler for Visible and NIR Imaging

July 22, 2014

By a News Reporter-Staff News Editor at Journal of Technology -- A patent by the inventors Tesar, John C. (Tucson, AZ); Cottle, Paul (Vancouver, CA); Fengler, John J. P. (North Vancouver, CA), filed on October 6, 2009, was published online on July 8, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8773756 is assigned to Novadaq Technologies Inc. (Mississauga, CA).

The following quote was obtained by the news editors from the background information supplied by the inventors: "Near-infrared (NIR) imaging using endoscopes has been described in the literature for various clinical applications. Typically, such an imaging modality utilizes a contrast agent (e.g. indocyanine green) that absorbs and/or fluoresces in the 700-900 nm range of the NIR. In some endoscopic imaging systems capable of high resolution simultaneous color and NIR imaging, none of the image sensors (if multiple image sensors are used) or specific pixels of an image sensor (if only a single color image sensor is used) are exclusively dedicated to NIR imaging. One exemplary imaging system, described in the Annex of the present disclosure, utilizes a red, green, blue (RGB) sensor assembly to acquire both color and NIR fluorescence images by employing the red image sensor to, alternately and in rapid succession, acquire both the red light required for the color image and NIR light required for the NIR image. This imaging system is intended to be used in conjunction with image-projecting optical instruments such as endoscopes, microscopes, colposcopes, etc. that have also been optimized for both visible light and NIR imaging applications. Specifically the optical instruments (i.e. endoscopes, microscopes, colposcopes, etc.) and the optical assemblies (optical couplers) that couple these instruments to the sensor assembly of the imaging system are constructed using appropriate visible and NIR transmitting optical materials and antireflection coatings and are optically designed to transmit visible and NIR images for which chromatic and geometric aberrations are minimized. FIG. 1 depicts a typical configuration of an optical instrument, optical coupler and imaging system such as that being described above.

"Although the preponderance of optical instruments currently in use are not optimized for both visible (VIS) and NIR light imaging, such instruments may still transmit sufficient NIR light that it may also be desirable to enable the previously described VIS-NIR imaging system for use with these conventional optical instruments. Conventional optical instruments are typically well-corrected for imaging throughout the visible spectrum, but without equivalent correction in the NIR, NIR images acquired with the aforementioned VIS-NIR imaging system through such optical instruments are likely to be of poor quality. Furthermore, although some of the NIR image aberrations introduced by conventional optical instruments may be corrected by applying compensating lens design techniques to the optical couplers, such techniques are typically not powerful enough to correct both the aberrations and the shift in focal plane between the visible and NIR images produced with such instruments. A novel optical coupler capable of correcting for the optical aberrations and for the difference in visible and NIR focal plane locations introduced when using conventional optical instruments is, consequently, highly desirable."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "The invention described in this disclosure is directed to an optical coupler that corrects for both the optical aberrations and the shift in focal plane between the visible and NIR images that is introduced by conventional optical instruments and enables those instruments to be used with a VIS NIR imaging system of the type described in the Annex to this application.

"Although well-corrected for visible light imaging and producing substantially coincident focal plane locations for images at wavelengths throughout the visible spectrum (400-700 nm), at NIR wavelengths (700-900 nm) conventional optical instruments will project poorly corrected images at focal plane locations substantially displaced from those for the visible spectrum images. This is particularly problematic for imaging systems using a single color image sensor onto which both visible light and NIR light images are projected. An exemplary single color image sensor is described in the Annex to this application. Conventional optical instruments are not compatible with such imaging systems without some correction to the NIR images that they project.

"The disclosed system utilizes a combination of correction mechanisms in a novel optical coupler to address the multiple challenges in compensating for the NIR imaging properties of conventional optical instruments without degrading the performance in the visible spectrum. Specifically, this VIS NIR optical coupler splits the optical path into visible and NIR paths within the optical coupler and thereby enables distributed correction for path length differences between the visible and NIR spectrum. The separate visible and NIR optical paths are recombined after compensation for optical path length difference and are then projected by a lens assembly that corrects for aberrations in the NIR without compromising the performance in the visible spectrum."

URL and more information on this patent, see: Tesar, John C.; Cottle, Paul; Fengler, John J. P.. Compensating Optical Coupler for Visible and NIR Imaging. U.S. Patent Number 8773756, filed October 6, 2009, and published online on July 8, 2014. Patent URL:

Keywords for this news article include: Novadaq Technologies Inc..

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Source: Journal of Technology

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