Calibration jig for optical tomographic imaging apparatus and method for generating a calibration conversion table

Patent metadata

Field	Value
Publication number	US-9322639-B2
Application number	US-201414505372-A
Country	US
Kind code	B2
Filing date	Oct 2, 2014
Priority date	Jul 2, 2008
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

A calibration jig allowing simple and repeatable calibration of a probe optical tomographic apparatus is disclosed. The jig includes a holding member removably attachable to an attachment section of the apparatus and a reflective surface held by the holding member. The reflective surface reflects measurement light emitted from an emitting section of the attachment section and directs reflected light back to the emitting section. If a probe of the apparatus is covered with a sheath, the jig may include a light transmitting member, which generates the same dispersion as dispersion at the sheath, between the emitting section and the reflective surface. The reflective surface may be a single reflective surface disposed within an area corresponding to twice a coherence length of the laser light with a zero path position of the reflective surface being the center of the area.

First claim

What is claimed is:

1. A method for generating a calibration conversion table using a calibration jig for calibrating an optical tomographic imaging apparatus,
the calibration jig including a holding member removably attachable to an attachment section of the optical tomographic imaging apparatus, wherein an optical probe is to be attached to the attachment section, and a reflective surface held by the holding member, the reflective surface reflecting measurement light emitted from an emitting section of the attachment section and directing reflected light back to the emitting section,
the calibration conversion table representing a relationship between wavenumber and displacement and being used for converting a first interference signal plotted along a displacement axis with constant displacement intervals into a second interference signal plotted along a wavenumber axis with constant wavenumber intervals,
the first interference signal being obtained by: attaching the calibration jig to the attachment section to optically couple the calibration jig to the apparatus in a removable manner; dividing low-coherent light having a wide emission wavelength band into reference light and the measurement light; emitting the measurement light from the emitting section; guiding the measurement light through the calibration jig and applying the measurement light to the reflective surface; combining the reference light with reflected light, the reflected light being reflected from the reflective surface and guided through the calibration jig; and spatially dispersing interference light of the combined reference light and reflected light with respect to frequency and detecting the interference light as the first interference signal with a plurality of spatially arrayed light receiving elements,
the method utilizing one or more processors, the method comprising:
attaching the calibration jig to the attachment section, from which the optical probe is detached;
extracting a group of points from the first interference signal plotted along the displacement axis, the group of points being plotted at equal intervals in the second interference signal plotted along the wavenumber axis;
finding a displacement value corresponding to each point of the group of points;
plotting, based on the displacement values, the group of points on the calibration conversion table at equal intervals along the wavenumber axis of the calibration conversion table; and
interpolating, using at least one processor, between the plotted points of the group of points.

2. The method for generating a calibration conversion table utilizing one or more processors as claimed in claim 1 , further comprising:
if a wavenumber spectrum of the first interference signal of the interference light contains a peak other than a peak corresponding to the reflective surface, cutting out a region of the peak corresponding to the reflective surface from the wavenumber spectrum;
applying, using at least one processor, inverse Fourier transform to the cut out region of the wavenumber spectrum to form a transformed interference signal; and
extracting the group of points from the transformed interference signal.

Assignees

• Terumo Corp

Inventors

• Watanabe Daisuke
• Teramura Yuichi

Classifications

• G01B9/0205

  of probe head · CPC title

• G01B9/02074

  of the detector · CPC title

• G01B9/02072 Primary

  by calibration or testing of interferometer · CPC title

• G01B9/02083

  characterised by particular signal processing and presentation · CPC title

• G06F17/17

  Function evaluation by approximation methods, e.g. inter- or extrapolation, smoothing, least mean square method ({G06F17/18 takes precedence } ; interpolation for numerical control G05B19/18) · CPC title