Optical scanning observation apparatus and optical scanning observation method

Patent metadata

Field	Value
Publication number	US-9993139-B2
Application number	US-201615362192-A
Country	US
Kind code	B2
Filing date	Nov 28, 2016
Priority date	May 28, 2014
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

Abstract

An optical scanning endoscope apparatus includes an optical fiber for illumination, a driver that drives the tip of the optical fiber for illumination in a Lissajous scan pattern, illumination lenses that irradiate an object of observation with irradiation light emitted from the tip of the fiber, a photodetector that detects light obtained from the object of observation by irradiation with the irradiation light and converts the light to an electrical signal, an image processor that generates an image based on the electrical signal output by the photodetector, and a phase adjustor that adjusts the phase of the drive waveform of the driver so as to correct a phase shift between the drive waveform of the tip of the fiber by the driver and the vibration waveform of the tip of the fiber.

First claim

The invention claimed is:

1. An optical scanning observation apparatus comprising:
a fiber configured to guide light from a light source and supported to allow a tip of the fiber to oscillate;
a driver configured to drive the tip of the fiber in a Lissajous scan pattern by vibrating the tip of the fiber at a first frequency in a first direction and at a second frequency in a second direction, the second direction being substantially orthogonal to the first direction, and the second frequency being different from the first frequency;
an optical system configured to irradiate an object of observation with irradiation light emitted from the tip of the fiber;
a photodetector configured to detect light obtained from the object of observation by irradiation with the irradiation light and convert the light to an electrical signal;
an image processor configured to generate an image based on the electrical signal output by the photodetector; and
a phase adjustor configured to adjust a phase of a drive waveform of the tip of the fiber by the driver in one or both of the first direction and the second direction so as to correct a phase shift between the drive waveform of the tip of the fiber by the driver and a vibration waveform of the tip of the fiber,
wherein the phase adjustor determines frequencies fx and fy so as to satisfy h following expressions and adjusts phases θx and θy,
X=A x sin(2π f x t+θ x )

Y=A y sin(2π f y t+θ y )

f x =( n+ 1)×fps

f y =n ×fps

where X is a drive waveform in the first direction, Y is a drive waveform in the second direction, A x and A y are amplitude in the first and the second direction, n is an integer, and fps is a frame rate.

2. The optical scanning observation apparatus of claim 1 , wherein the phase adjustor adjusts the phase of the drive waveform so as to minimize distortion of the image generated by the image processor.

3. The optical scanning observation apparatus of claim 1 , further comprising:
a display configured to display the image generated by the image processor; and
an input interface configured to receive input of an adjustment amount of the phase to be adjusted by the phase adjuster in one or both of the first direction and the second direction.

4. The optical scanning observation apparatus of claim 1 , wherein the phase adjuster adjusts the phase of the drive waveform of the tip of the fiber by the driver based on a phase of the drive waveform determined so as to maximize resolution of an image generated by the image processor for a predetermined resolution chart placed at an observation position of the object of observation.

5. The optical scanning observation apparatus of claim 1 , wherein the phase shift between the drive waveform and the vibration waveform of the tip of the fiber is determined based on a resonance frequency and Q value of the tip of the fiber.

6. The optical scanning observation apparatus of claim 5 , further comprising a measurement unit configured to measure the resonance frequency and Q value of the tip of the fiber.

7. The optical scanning observation apparatus of claim 6 , wherein the measurement unit measures the resonance frequency and Q value of the tip of the fiber by measuring impedance of an electric circuit of the driver.

8. The optical scanning observation apparatus of claim 1 , wherein the driver drives the tip of the fiber in one or both of the first direction and the second direction at a frequency f satisfying
fc{ 1−1/(2 Q )}< f<fc{ 1+1/(2 Q )}

where fc is a resonance frequency and Q is a Q value of the tip of the fiber.

9. An optical scanning observation method for driving a tip of a fiber in a Lissajous scan pattern by vibrating the tip of the fiber at a first frequency in a first direction and at a second frequency in a second direction, the second direction being substantially orthogonal to the first direction, and the second frequency being different from the first frequency, irradiating an object of observation with irradiation light emitted from the tip of the fiber, detecting light obtained from the object of observation by irradiation with the irradiation light, converting the light to an electrical signal, and generating an image based on the electrical signal; the method comprising:
adjusting a phase of a drive waveform of the tip of the fiber in one or both of the first direction and the second direction so as to correct a phase shift between the drive waveform of the tip of the fiber and a vibration waveform of the tip of the fiber; and
vibrating the tip of the fiber using the drive waveform with adjusted phase and observing an image,
wherein adjusting the phase comprises determining frequencies fx and fy so as to satisfy the following expressions and adjusting phases θx and θy,
X=A x sin(2π f x t+θ x )

Y=A y sin(2π f y t+θ y )

f x =( n+ 1)×fps

f y =n ×fps

where X is a drive waveform in the first direction, Y is a drive waveform in the second direction, A x and A y are amplitudes in the first and the second direction, n is an integer, and fps is a frame rate.

10. The optical scanning observation apparatus of claim 1 ,
wherein the light source comprises a laser for phase correction and a laser for image observation,
wherein the optical scanning observation apparatus is provided with a light-blocking portion, between the tip of the fiber and the object of observation, which blocks only the irradiation light from the laser for phase correction and transmits the irradiation light from the laser for image observation, and
wherein the phase adjuster is configured to adjust the phase so that the image obtained by oscillating the laser for image observation has same shape as the shape of the light-blocking portion obtained by oscillating the laser for phase correction.

11. The optical scanning observation method of claim 9 ,
wherein the irradiation light is emitted from a laser for phase correction and a laser for image observation, and
wherein the step of adjusting the phase includes adjusting the phase so that the image obtained by oscillating the laser for image observation has same shape as the shape of the light-blocking portion obtained by oscillating the laser for phase correction.

Assignees

• Olympus Corp

Inventors

• Shimamoto Atsuyoshi

Classifications

• A61B1/0638

  providing two or more wavelengths · CPC title

• A61B1/00172 Primary

  with means for scanning · CPC title

• A61B1/063

  for monochromatic or narrow-band illumination · CPC title

• A61B1/05

  characterised by the image sensor, e.g. camera, being in the distal end portion · CPC title

• G02B23/2469

  using optical fibres · CPC title