News Column

Patent Issued for Silicon Optical Bench OCT Probe for Medical Imaging

July 30, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- A patent by the inventors Flanders, Dale C. (Lexington, MA); Getz, James W. (Harvard, MA); Atia, Walid A. (Lexington, MA); Whitney, Peter S. (Lexington, MA); Kuznetsov, Mark E. (Lexington, MA), filed on July 19, 2013, was published online on July 15, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8781287 is assigned to Axsun Technologies, Inc. (Billerica, MA).

The following quote was obtained by the news editors from the background information supplied by the inventors: "Coherence analysis relies on the use of the interference phenomena between a reference wave and an experimental wave or between two parts of an experimental wave to measure distances and thicknesses, and calculate indices of refraction of a sample. Optical Coherence Tomography (OCT) is one example technology that is used to perform usually high-resolution cross sectional imaging. It is applied to imaging biological tissue structures, for example, on microscopic scales in real time. Optical waves are reflected from the tissue, in vivo, ex vivo or in vitro, and a computer produces images of cross sections of the tissue by using information on how the waves are changed upon reflection.

"The original OCT imaging technique was time-domain OCT (TD-OCT), which used a movable reference mirror in a Michelson interferometer arrangement. In order to increase performance, variants of this technique have been developed using two wavelengths in so-called dual band OCT systems.

"In parallel, Fourier domain OCT (FD-OCT) techniques have been developed. One example uses a wavelength swept source and a single detector; it is sometimes referred to as time-encoded FD-OCT (TEFD-OCT) or swept source OCT. Another example uses a broadband source and a spectrally resolving detector system and is sometimes referred to as spectrum-encoded FD-OCT or SEFD-OCT.

"In scanning OCT, a light beam is focused onto the sample under test by a probe. Returning light is combined with light from a reference arm to yield an interferogram, providing A-scan or Z axis information. By scanning the sample relative to the probe, linear or two dimensional scans can be used to build up a volumetric image. One specific application involves the scanning of arteries, such as coronary arteries. The probe is inserted to an artery segment of interest using a catheter system. The probe is then rotated and drawn back through the artery to produce a helical scan of the inner vessel wall.

"Traditionally, scanning OCT probes have been constructed from gradient refractive index (GRIN) lens and fold mirrors. Optical fibers are used to transmit optical signals to the probe at the distal end of the catheter system. The GRIN lens at the end of the fiber produces a collimated or focused beam of light and focuses incoming light onto the end of the optical fiber. The fold mirror couples to the GRIN lens to a region lateral to the probe."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "In general, according to one aspect, the invention features an optical probe for emitting and/or receiving light within a body. The probe comprises an optical fiber that transmits and/or receives an optical signal, a silicon optical bench including a fiber groove running longitudinally that holds an optical fiber termination of the optical fiber and a reflecting surface that optically couples an endface of the optical fiber termination to a lateral side of the optical bench.

"In embodiments, a lens structure is secured to the optical bench over the fold mirror surface. In some cases, the lens is anamorphic.

"Further, the optical bench preferably comprises a blind groove section having a depth greater than at least part of the fiber groove with a distal end of the blind groove section forming the reflecting surface, which can be flat or curved. In the case of a curved reflecting surface, the optical power provided by the curved surface can be used to avoid the need for the lens structure.

"In other aspects of embodiments, the fiber groove comprises a first depth section for fiber strain relief and a second depth section, the optical fiber comprising a sheathed portion in the first depth section of the optical bench and a bare portion in the second depth section of the optical bench.

"In examples, a top bench is used over the fiber groove with the optical fiber termination being sandwiched between the top bench and the silicon optical bench. This top bench can have a fiber groove with a first depth section and a second depth section, a sheathed portion of the optical fiber being located in the first depth section of the top bench and a bare portion of the optical fiber being located in the second depth section of the top bench.

"A housing is preferably provided around the bench. This housing comprises a optical port opposite the reflecting surface, through which the termination of the optical fiber is optically coupled to a region lateral to the probe.

"In general according to another aspect, the invention features an optical probe for emitting and/or receiving light within a body. The probe comprises an optical fiber that transmits and/or receives an optical signal, a housing that contains an optical fiber termination of the optical fiber, the housing comprising at least a tubular section and a cap section, in which the cap section fits in a slot in the tubular section.

"Preferably, an optical bench is provided in the slot of the tubular section and under the cap section, the optical fiber being held between the optical bench and the cap section. This cap section can comprise a groove running longitudinally on a backside, the optical fiber being held in the groove. An end section is useful for closing the slot at the distal end of the housing.

"In general according to another aspect, the invention features an optical probe for emitting and/or receiving light within a body. This probe comprises an optical fiber that transmits and/or receives an optical signal and a housing that contains an optical fiber termination of the optical fiber, the housing comprising at least an electroformed tubular section.

"In general according to still another aspect, the invention features a method for forming an optical probe for emitting and/or receiving light. This method comprises anisotropically etching wafer material to form grooves for holding optical fibers and singulating optical benches including the grooves from the wafer material.

"Preferably blind grooves are formed in the wafer material, and coated to be reflective.

"In general according to another aspect, the invention features a method for forming an optical probe for emitting and/or receiving light. This method comprises photolithographically patterning a resist layer; electroforming housings in the patterned resist layer, and inserting optical fiber terminations into the housings.

"Preferably, the step of electroforming comprises electroplating. The method can also include electroforming cap sections that fit into slots in the housings along with installing optical benches in the housings, the optical fiber terminations being held on the optical benches.

"The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention."

URL and more information on this patent, see: Flanders, Dale C.; Getz, James W.; Atia, Walid A.; Whitney, Peter S.; Kuznetsov, Mark E.. Silicon Optical Bench OCT Probe for Medical Imaging. U.S. Patent Number 8781287, filed July 19, 2013, and published online on July 15, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8781287.PN.&OS=PN/8781287RS=PN/8781287

Keywords for this news article include: Axsun Technologies, Axsun Technologies Inc., Silicon, Technology.

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Source: Journal of Engineering


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