JPH08211425A - Optical scanner - Google Patents

Abstract

PURPOSE: To provide a low-cost and compact optical scanner capable of simultaneously scanning plural measurement points with one time of scanning. CONSTITUTION: This optical scanner is capable of simultaneously scanning the plural measurement points on a scanning plane and has a nonlinear optical medium 1 which generates the refractive index distribution meeting the wavelength of incident light so as to deflect light in one direction and a diffraction grating 8 to diffract light in another direction. Control light rays 2, 3 form the dynamic diffraction grating having periodic intensity distributions by interfering with each other within the nonlinear optical material 1 when these control light rays 2, 3 are made incident on the nonlinear optical medium 1. The light 6 of a wavelength λ to be controlled is diffracted at a prescribed angle and is then deflected as the light 7 to be controlled in the prescribed direction when this light 6 is made incident on this dynamic diffraction grating. At this time, the light 9 diffracted from the diffraction grating 8 is eventually deflected in a prescribed direction at the time the light 7 to be controlled is made incident on the diffraction grating 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanner for scanning a light beam in two dimensions.

[0002]

2. Description of the Related Art Conventionally, as a method of two-dimensionally scanning a light beam by an optical scanner of this kind, for example, a method of changing the direction of reflected light by rotating a mirror by a motor or the like, or a diffraction grating or a hologram on a disk is used. There is known a method of changing the direction of a light beam by changing the angle between the light beam and a diffraction grating by rotating these structures (hereinafter, referred to as prior art 1).

As a method other than such a mechanical scanning method, there is known a method of performing one-dimensional scanning by changing the direction of a light beam by using an acousto-optic device (Japanese Patent Laid-Open No. 62-75622). (See Japanese Patent Publication). That is, by propagating an ultrasonic wave to the ultrasonic medium in the acousto-optic element, a wave having a refractive index change corresponding to the wavelength and amplitude of the ultrasonic wave is generated in the ultrasonic medium. Since the wave of the refractive index change acts as a kind of diffraction grating, the light beam incident on the diffraction grating is diffracted and bent in a predetermined direction (hereinafter, referred to as Prior Art 2).

There is also known a method of scanning each of two-dimensionally arranged measurement points by using, for example, a two-dimensional scanner. That is, in a state in which the x axis and the y axis are defined on the scanning plane, first, each point is scanned in the x axis direction, and then the position of each scanned point is slightly moved in the y axis direction. And
This is a method of repeating the operation of scanning each measurement point to be scanned next in the x-axis direction. When this method is carried out, for example, a method of scanning an optical scanner capable of deflecting a light beam in a one-dimensional direction twice or a two-dimensional optical scanner provided with a mirror or the like capable of changing an angle in two axial directions is used. A scanning method is adopted (hereinafter referred to as prior art 3).

[0005]

However, in the method of the prior art 1, since it is necessary to maintain the mechanical operation at a certain accuracy, it is difficult to miniaturize the device, which increases the manufacturing cost. There is a problem that it will end up. Further, in both the methods of the conventional art 2 and the conventional art 3, since scanning in two directions must be repeated, there arises a problem that it is difficult to shorten the scanning time.

The present invention has been made to solve the above problems, and an object thereof is to provide a low-cost and compact optical scanner capable of simultaneously scanning a plurality of measurement points in one scan. To provide.

[0007]

In order to achieve such an object, an optical scanner according to the present invention is an optical scanner capable of simultaneously scanning a plurality of measurement points on a scanning surface, which is unidirectional. A first diffracting means for diffracting light and a second diffracting means for diffracting light in the other direction are provided, and one of the first and second diffractive means is a periodic diffractive means. The refractive index distribution is controllable.

[0008]

According to the present invention, the light diffracted by the first and second diffracting means is simultaneously scanned on a plurality of measurement points on the scanning surface.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of the present invention will be described with reference to FIGS. 1 and 2, and then the optical scanner according to each embodiment of the present invention to which this principle is applied will be described with reference to FIGS. explain.

1 and 2 show a scanning optical system for changing the direction of controlled light by changing the wavelength of control light. First, as shown in FIG. 1, a scanning optical system according to the first principle of the present invention will be described.

This scanning optical system is provided with a non-linear optical medium 1 whose refractive index changes according to the wavelength of irradiation light. For convenience of description, the optical interface of the nonlinear optical medium 1 on which light is incident is positioned within a plane (hereinafter referred to as an xy plane) defined by the x-axis and the y-axis orthogonal to each other,
The z axis is defined in the direction perpendicular to the optical interface (that is, the xy plane).

At the optical interface of the nonlinear optical medium 1 thus positioned, coherent control light 2, 3 from two directions is provided.
Suppose that is incident. These control lights 2,
3 are both emitted from the same tunable light source, and x
After traveling in a plane defined by the z-axis and the z-axis (hereinafter referred to as zx plane), the light is incident on the nonlinear optical medium 1 at the same incident angle θ [rad] from directions symmetrical to the z-axis. It is assumed that

When such control lights 2 and 3 are incident on the nonlinear optical medium 1, the control lights 2 and 3 interfere with each other in the nonlinear optical medium 1 to have a periodic intensity distribution. Form interference fringes.

For example, when the wavelengths of the two control lights 2 and 3 are Λ, the period of the interference fringes can be expressed as d = (Λ / 2) sin θ.

At this time, since a refractive index distribution corresponding to the interference fringes is generated in the nonlinear optical medium 1, a dynamic diffraction grating parallel to the y axis is formed. Now, the controlled light 4 having the wavelength λ that has traveled in the zx plane has an incident angle α _{0 with} respect to the z axis.
When incident on the nonlinear optical medium 1 at [rad], the controlled light 4 is sin ⁻¹ {(d / λ) with respect to the z axis by the dynamic diffraction grating formed in the nonlinear optical medium 1. −sin α ₀ } [rad] (1) d; Diffracted at an angle of the interval of interference fringes.

Here, when the wavelength Λ of the control lights 2 and 3 is changed, the spacing d of the interference fringes is changed, so that the grating spacing of the dynamic diffraction grating formed in the nonlinear optical medium 1 is also changed. At this time, the controlled light 5 diffracted from the nonlinear optical medium 1 at the angle of (1) above is indicated by an arrow A in the zx plane.
Deflected in the direction.

As a result, the controlled light 5 is linearly scanned on the scanning surface (not shown) arranged in the forward direction of the controlled light 5. In the above-mentioned principle, the control lights 2 and 3 and the controlled light 4 both travel in the zx plane and then enter from the same plane of the nonlinear optical medium 1. However, they do not necessarily travel in the zx plane. Even if it does not exist, or even if it does not enter from the same surface, the same effect can be obtained. Further, according to the above-mentioned principle, the control lights 2 and 3 are incident on the nonlinear optical medium 1 from the direction symmetrical with respect to the z-axis, but the incident light is not necessarily required to be incident from the direction symmetrical with respect to the z-axis. The effect of can be obtained. Furthermore, in the above description of the principle, the transmissive scanning optical system that uses the diffracted light diffracted when passing through the nonlinear optical medium 1 as the controlled light 5 is used. The same action and effect can be obtained also in the reflection type scanning optical system using the diffracted diffracted light as the controlled light 5.

Next, as shown in FIG. 2, a scanning optical system according to the second principle of the present invention will be described. In this scanning optical system, a diffraction grating 8 having a grating spacing of D is provided behind the nonlinear optical medium 1 along the optical axis traveling direction. The diffraction grating 8 is arranged so that the direction of the diffraction grating is orthogonal to the dynamic diffraction grating formed in the nonlinear optical medium 1, and its optical interface is perpendicular to the z axis. It is positioned. The controlled light 6 incident on the nonlinear optical medium 1 is maintained such that its wavelength spreads over a predetermined wavelength range, that is, a wavelength range λ _{0 to} λ ₁ . The diffraction grating 8 is positioned on a plane defined by the x'axis and the y'axis (hereinafter referred to as the x'y 'plane). The x'y' plane is parallel to the xy plane. Stipulated to be. The y'z plane means a plane defined by the y'axis and the z axis. Furthermore, the x'axis and z
The plane defined by the axis (hereinafter referred to as the zx 'plane) is defined on the same plane as the zx plane.

Under the above conditions, the component having the wavelength λ in the controlled light 6 having the wavelength spread is generated by the dynamic diffraction grating formed in the nonlinear optical medium 1 with respect to the z-axis. Therefore, the controlled light 7 diffracted from the nonlinear optical medium 1 is
According to the wavelength spread, the light travels to the diffraction grating 8 with a predetermined spread angle in the zx plane.

Of the controlled light 7 irradiated on the diffraction grating 8, the controlled light component having the wavelength λ is diffracted from the zx ′ plane in the direction forming the angle sin ⁻¹ (λ / D) [rad]. . As a result, the controlled light 9 is linearly scanned on the scanning surface arranged in front of the controlled light in the traveling direction (see the area encircled by the arrow B in the figure).

Here, when the wavelength Λ of the control lights 2 and 3 is changed, the controlled light 7 diffracted from the nonlinear optical medium 1 is
Since the light is deflected in the direction of arrow A in the figure, the controlled light 9 diffracted by the diffraction grating 8 is deflected in the direction of arrow B in the figure.

As a result, the planar scanning is performed on the scanning surface arranged in front of the controlled light 9 in the traveling direction (see the area surrounded by a square B in the figure). The surface information of the scanning surface can be measured collectively.

In the scanning optical system of FIG. 2, the controlled light 7 is made to enter the incident surface of the diffraction grating 8 substantially perpendicularly, but it is not always necessary to make it incident perpendicularly. Further, the diffraction grating 8 may be either a reflection type or a transmission type. Further, in the scanning optical system of FIG. 2, the diffraction grating 8 is arranged behind the nonlinear optical medium 1, but the nonlinear optical medium 1
The diffraction grating 8 may be arranged in front of. Further, the directions of the diffraction grating 8 and the dynamic diffraction grating formed in the nonlinear optical medium 1 do not necessarily have to be orthogonal to each other.

In the scanning optical system of FIG. 2, the wavelength Λ of the control lights 2 and 3 is changed while detecting the scattered light generated from the object when the controlled light 9 is focused on the object. To scan. Since such controlled light 9 is diffracted in different directions corresponding to the value of the wavelength λ, light having different wavelengths is condensed at different points on the object. At this time, the position information on the object is measured by dispersing the scattered light generated from each point on the object and detecting the wavelength of the scattered light.

As described above, according to the scanning optical system of FIG. 2, the image of the object is obtained based on the position information on the object and the scattered light intensity measured from the wavelength Λ of the control lights 2 and 3 and the wavelength λ of the scattered light. Can be configured. However, if the object has a sharp absorption structure or a reflection structure within the range of the wavelength spread of the controlled light 6, an accurate image may not be reproduced.

According to the scanning optical system of FIG. 2, the deflection angle of the controlled light 7 generated from the dynamic diffraction grating formed in the nonlinear optical medium 1 is incident on the dynamic diffraction grating. Since the scanning region may be distorted because it changes according to the value of the wavelength λ of the controlled light 6, even in such a case, the grating spacing and the grating direction of the dynamic diffraction grating are adjusted. By doing so, the distortion of the scanning region can be reduced.

Next, an optical scanner according to the first embodiment of the present invention to which the above principle is applied will be described with reference to FIGS. 3 and 4. 3 and 4 schematically show the configuration of an endoscope apparatus incorporating the optical scanner of this embodiment. Note that FIG. 3 shows the configuration of the endoscope tip portion, and FIG. 4 shows the overall configuration of the endoscope device other than the endoscope tip portion.

As shown in FIG. 4, in the endoscope apparatus applied to this embodiment, the wavelength tunable light source 31 is controlled by the wavelength controller 39 so as to emit control light having a predetermined wavelength.
And a light source 33 that emits controlled light having a wavelength range having a predetermined spread, that is, a wavelength spread.

Here, as the variable wavelength light source 31, for example, a continuous wave dye laser (hereinafter, referred to as CW dye laser).
Is used, tens of nanometers (n
The wavelength range of m) will be swept. The wavelength of this wavelength tunable CW dye laser is selected by a wavelength selection element such as a birefringent filter or a diffraction grating in the laser oscillator. Further, the light source 33 is configured to emit controlled light in a characteristic wavelength range selected by a filter or the like, out of light emitted from a white light source such as a tungsten lamp.

The control light emitted from the variable wavelength light source 31 is
The light is guided to the tip portion 30a of the endoscope 30 via the single mode optical fiber 32. Further, the controlled light emitted from the light source 33 is guided to the tip 30a of the endoscope 30 via the single mode optical fiber 34.

As shown in FIG. 3, the distal end portion 3 of the endoscope 30 is shown.
At 0a, the control light emitted from the single mode optical fiber 32 is converted into a parallel light flux by the lens 12 and then split into two directions via the semitransparent mirror 13.

The divided control light is transmitted to the pair of mirrors 14 and 15
After being reflected by the nonlinear optical medium 16, the nonlinear optical medium 16 is irradiated therewith to form a dynamic diffraction grating in the nonlinear optical medium 16. As the non-linear optical medium 16, for example, a photorefractive medium such as BaTiO ₃ single crystal or a dye film having non-linearity in a wide wavelength range is applied.

On the other hand, at the tip portion 30a of the endoscope 30, the controlled light emitted from the single mode optical fiber 34 is converted into a parallel light flux by the lens 18,
Non-linear optical medium 16 through three mirrors 19, 20, 21
Is irradiated.

At this time, the controlled light emitted to the nonlinear optical medium 16 is deflected in a predetermined direction by the dynamic diffraction grating formed in the nonlinear optical medium 16. In such a state, the control light and the controlled light deflected in a predetermined direction are transmitted from the nonlinear optical medium 16, but the control light is blocked by the filter 22 and only the controlled light is selected. Is output.

The controlled light output from the filter 22 is
The diffraction grating 26 is illuminated through the three mirrors 23, 24 and 25. The controlled light with which the diffraction grating 26 is irradiated forms an angle according to the wavelength component thereof and is diffracted from the diffraction grating 26, and then an object (positioned in front of the distal end portion 30a of the endoscope 30 by the lens 27 ( (Not shown), the light is linearly condensed.

As a result, a plurality of measurement points arranged in a line on the object are scanned simultaneously. At this time, the controlled light, that is, the scattered light simultaneously scattered from a plurality of measurement points on the object is simultaneously condensed by the lens 28 in the distal end portion 30a of the endoscope 30, and then dispersed through the multimode optical fiber 35. Light is guided to the container 36 (see FIG. 4).

As shown in FIG. 4, the scattered light guided to the spectroscope 36 is dispersed by the spectroscope 36, and the photodetector array 37 simultaneously measures the light intensity for each wavelength. Then, the measurement data is transmitted to the image forming device 40.

When such a series of operations is completed, the wavelength sweeping device 38 transmits a wavelength change signal for changing the wavelength of the control light to the wavelength control device 39. At this time, it is preferable to set such that the changing direction of the wavelength is always the same direction. By setting in this way, it becomes possible to change the position of the controlled light linearly condensed on the object on the object.

Subsequently, the wavelength control device 39 operates the wavelength selection element of the variable wavelength light source 31 to change the wavelength of the control light emitted from the variable wavelength light source 31, based on the wavelength change signal. Then, by repeating the above-described operation again, the object surface is scanned once.

During such scanning, the image construction device 40 associates the position on the object with the scattered light intensity based on the respective signals output from the wavelength sweep device 38 and the photodetector array 37. After that, the image is formed and then the image is output to the image display device 41.

As a result, the surface information of the surface of the object is collectively measured by one scanning. As described above, according to the optical scanner of the present embodiment, a plurality of measurement points continuously arranged on the object are simultaneously scanned by one scanning, so that the surface information of the object surface is collectively collected by one scanning. It is possible to provide a low-priced and compact optical scanner capable of performing the measurement.

Next, an optical scanner according to the second embodiment of the present invention will be described with reference to FIGS. 5 and 6 schematically show the configuration of an endoscope apparatus incorporating the optical scanner of this embodiment. In addition, in FIG.
The configuration of the endoscope tip portion is shown, and FIG. 6 shows the overall configuration of the endoscope apparatus other than the endoscope tip portion.

The optical scanner of the present embodiment has the non-linear optical medium 16 applied to the first embodiment (see FIG. 3) and the dynamic diffraction grating formed in the non-linear optical medium, and the acousto-optic device 5 is provided.
It is characterized in that it is configured by replacing with 4.

As shown in FIG. 6, the endoscope apparatus applied to this embodiment is provided with a light source 73 for emitting controlled light having a wavelength range having a predetermined spread, that is, a wavelength spread. The light source 73 is configured to emit controlled light in a characteristic wavelength range selected by a filter or the like among lights emitted from a white light source such as a tungsten lamp.

The controlled light emitted from such a light source 73 is transmitted through the single mode optical fiber 74 to the endoscope 7
The light is guided to the front end portion 70a of 0. As shown in FIG. 5, at the distal end portion 50 of the endoscope 70, the controlled light emitted from the single-mode optical fiber 74 is converted into a parallel light flux by the lens 52, and then is transmitted to the acoustooptic device 54 via the mirror 53. Is irradiated.

A predetermined ultrasonic wave is propagated to the acousto-optic element 54 based on the frequency change signal transmitted from the acousto-optic element driving device 71 through the output line 72. A wave of a refractive index change corresponding to the wavelength and amplitude of the ultrasonic wave (this wave acts as a diffraction grating) is generated in 54.

As a result, the controlled light with which the acousto-optic element 54 is irradiated is scattered by the diffraction grating formed in the acousto-optic element 54 and deflected in a predetermined direction. The controlled light deflected by the acousto-optic device 54 has three mirrors 55, 5
The diffraction grating 58 is irradiated via 6, 57.

At this time, the controlled light with which the diffraction grating 58 is irradiated forms an angle corresponding to the wavelength component thereof and the diffraction grating 5
After being diffracted from 8, the light is linearly condensed by the lens 59 onto an object (not shown) arranged in front of the distal end portion 70a of the endoscope 70.

As a result, a plurality of measurement points which are continuously arranged linearly on the object are simultaneously scanned. At this time, the controlled light, that is, the scattered light that is simultaneously scattered from a plurality of measurement points on the object is simultaneously condensed by the lens 60 in the distal end portion 70a of the endoscope 70, and then the spectroscope 76 is passed through the optical fiber 75. (See FIG. 6).

As shown in FIG. 6, the scattered light guided to the spectroscope 76 is dispersed by the spectroscope 76, and then the photodetector array 77 simultaneously measures the light intensity for each wavelength. Then, the measurement data is transmitted to the image forming device 79.

When such a series of operations is completed, the deflection angle sweeping device 78 transmits a frequency change signal for changing the frequency of ultrasonic waves to the acoustooptic device driving device 71.
Then, the acousto-optic element drive device 71 outputs a predetermined control signal based on the frequency change signal. The control signal output at this time is input to the acousto-optic element 54 via the output line 72. As a result, the frequency of the ultrasonic wave propagated to the acousto-optic element 54 changes, so that the deflection direction of the controlled light changes. Then, by repeating the above-described operation again, the object surface is scanned once.

During such scanning, the image construction device 79 associates the position on the object with the scattered light intensity based on the respective signals output from the deflection angle sweep device 78 and the photodetector array 77. After the processing is performed to form the image, the image is output to the image display device 80.

As a result, the surface information of the surface of the object is collectively measured by one scanning. As described above, according to the optical scanner of the present embodiment, a plurality of measurement points continuously arranged on the object are simultaneously scanned by one scanning, so that the surface information of the object surface is collectively collected by one scanning. It is possible to provide a low-priced and compact optical scanner capable of performing the measurement.

Although the description has been given based on the embodiments, the present invention includes the following inventions. (1) An optical scanner capable of simultaneously scanning a plurality of measurement points on a scanning surface, the first diffracting means for diffracting light in one direction and the second diffracting means for diffracting light in the other direction. An optical scanner comprising: a diffractive means of one of the first and second diffractive means, the periodic diffractive index distribution being controllable.

This invention is based on the principle of the present invention (see FIGS. 1 and 2).
(See) applies. (2) One of the first and second diffracting means is constituted by a non-linear optical medium that causes a change in refractive index according to the wavelength of light incident on the diffracting means. The optical scanner according to (1) above.

This invention is a first embodiment of the present invention (see FIG. 3).
(See) applies. (3) Either one of the first and second diffractive means causes a predetermined ultrasonic wave to propagate,
The optical scanner according to (1) above, which is configured by an acousto-optic element that causes a change in refractive index corresponding to the wavelength and amplitude of the ultrasonic wave.

The present invention is a second embodiment of the present invention (see FIG. 5).
(See) applies. (4) An optical scanner as described in (2) or (3) above, and an optical system that collects scattered light generated when a plurality of measurement points on a scanning surface are simultaneously scanned by the optical scanner. ,
A spectroscopic optical system that disperses the scattered light, a photodetector that simultaneously detects the light intensity of the scattered light that is spectroscopically dispersed by the spectroscopic optical system, and a predetermined image processing for the detection data output from the photodetector. And an image forming device that outputs the surface information of the scanning surface.

The present invention corresponds to the endoscope apparatus (see FIGS. 4 and 6) applied to the first and second embodiments. (5) The two-dimensional optical scanner according to (4), wherein the photodetector uses a photodetector array. The present invention corresponds to the endoscope device (see FIGS. 4 and 6) applied to the first and second embodiments.

[0059]

According to the optical scanner of the present invention, the surface information of the object surface can be obtained by one scanning by simultaneously scanning a plurality of measurement points continuously arranged on the object by one scanning. It is possible to provide a low-priced and compact optical scanner capable of collectively measuring.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a configuration of a scanning optical system according to a first principle of the present invention.

FIG. 2 is a perspective view schematically showing a configuration of a scanning optical system according to a second principle of the present invention.

FIG. 3 is a diagram schematically showing an internal configuration of a distal end portion of an endoscope of an endoscope apparatus in which an optical scanner according to a first embodiment of the present invention is incorporated, in which (a) is one direction. Is a side view of the other direction, and (c) is a front view seen from the front of the tip of the endoscope.

FIG. 4 is a diagram schematically showing an overall configuration of an endoscope apparatus incorporating the optical scanner according to the first embodiment of the present invention.

FIG. 5 is a diagram schematically showing an internal configuration of an endoscope distal end portion of an endoscope apparatus incorporating an optical scanner according to a second embodiment of the present invention, in which (a) is one direction. Is a side view of the other direction, and (c) is a front view seen from the front of the tip of the endoscope.

FIG. 6 is a diagram schematically showing the overall configuration of an endoscope apparatus incorporating an optical scanner according to a second embodiment of the present invention.

[Explanation of symbols]

1 ... Nonlinear optical medium, 2, 3 ... Control light, 4, 7, 9 ... Controlled light, 8 ... Diffraction grating, λ ... Wavelength.

Claims (3)

[Claims] 1. An optical scanner capable of simultaneously scanning a plurality of measurement points on a scanning surface, the first diffracting means for diffracting light in one direction and the second diffracting means for diffracting light in the other direction. An optical scanner, wherein one of the first and second diffractive means is configured to control a periodic refractive index distribution. 2. The diffractive means of either the first diffractive means or the second diffractive means is constituted by a non-linear optical medium that causes a change in refractive index according to the wavelength of light incident on the diffractive means. The optical scanner according to claim 1, which is characterized in that. 3. An acousto-optic device that causes a change in refractive index corresponding to the wavelength and amplitude of an ultrasonic wave by propagating a predetermined ultrasonic wave in one of the first and second diffracting means. The optical scanner according to claim 1, wherein the optical scanner is configured by an element.