JP2017070357A - Imaging device, operation method of imaging device, and scanning position detector in imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire a high resolution fundus image in a short time by detecting a scanning position of measuring light quickly and accurately.SOLUTION: An imaging device for scanning measuring light on an object to be examined, and generating an image based on the reflection light from the object to be examined includes: a scanning mechanism for scanning the measuring light in a scanning range of the object to be examined; a light blocking part for transmitting or blocking at least part of the measuring light in an arbitrary region set corresponding to the scanning range; a light detection part for detecting at least part of the measuring light transmitted through or reflected by the arbitrary region; a state detection part for detecting a drive state of the scanning mechanism based on the at least part of the measuring light that has been detected; and an image generation means for generating an image based on the reflected light and the detected drive state.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an imaging apparatus that obtains an image of an inspection object by scanning laser light on the inspection object and acquiring reflected light from the inspection object at an appropriate timing, and an operation method of the imaging apparatus. The present invention also relates to an apparatus for detecting a scanning position of laser light applicable to the imaging apparatus.

  As an object to be inspected, for example, a fundus inspection apparatus is known as an imaging apparatus that obtains an image of a human eyeball. There is a scanning laser ophthalmoscope (SLO) as a type of fundus inspection apparatus that images the bottom surface of the eyeball. The SLO scans a finely spotted laser beam in each of the main and sub scanning directions, acquires the reflected light at an appropriate timing, and outputs the fundus image by computer processing. A feature of SLO is that it is possible to obtain a fundus image with higher resolution and contrast than a general fundus camera.

  In recent years, by introducing a mechanism of adaptive optics (Adaptive Optics: AO) as shown in Patent Document 1, aberrations of the cornea and crystalline lens of the human eye are removed, and the resolution of the photoreceptor cell (several μm) level of the fundus is obtained. There is also a device (AO-SLO). Alternatively, there is an ophthalmoscope that acquires information in the depth direction from the coherence of irradiation light and reflected light using the principle of optical coherence tomography (OCT) and measures a tomographic image of the fundus.

  By the way, as a method of scanning so-called measurement light typified by laser light in such an apparatus, use of a polygon mirror, a resonance mirror, or the like can be given. However, the scanning timing and amplitude of these devices vary irregularly due to the influence of air resistance and mechanical operation. In a general laser printer using such scanning means, a photodiode called a BD sensor or the like is used in order to correct image disturbance due to these fluctuations. Specifically, the BD sensor is disposed at a predetermined position, and the relationship between the scanning time of the measuring light and the scanning position is detected by a pulse output obtained when the measuring light passes therethrough.

  Even in the SLO, it is necessary to detect the scanning position of the measurement light on the object to be inspected as in the laser printer described above. However, since the scanning range of the scanner is arbitrarily set according to an instruction from a doctor or the like who operates the apparatus, the location where the scanning position is detected also changes accordingly. Patent Documents 2 to 4 disclose techniques for changing the position of the scanning position detection sensor in accordance with the change in the scanning range and the maximum deflection angle (amplitude) in the resonant scanner.

JP 2014-209980 A JP 2012-237795 A JP 2004-286508 A JP 2002-214073 A

  In the case of the method of mechanically moving the scanning position detector disclosed in Patent Document 2 and the like, there is a limit to satisfy simultaneously the improvement of the detection accuracy of the scanning position, the reduction of the measurement time, and the miniaturization of the apparatus.

  Here, in AO-SLO, in order to obtain resolution at the photoreceptor cell level, the detection accuracy of the scanning position of the measurement light also needs an accuracy of several μm. Some products such as general actuators have a minimum mechanical movement accuracy of about several μm. However, the moving scanning position detector described above needs to be designed to be robust so that the vibration of the motor does not propagate to other optical devices. This is disadvantageous for small and low-cost machine design. In addition, the movement accuracy and movement speed of the actuator are in a trade-off relationship. With a motor having the movement accuracy required for the AO-SLO device, position adjustment takes time, and the waiting time becomes longer. Will increase.

  As described above, in an imaging apparatus that images the fundus and the like, it is preferable to avoid the method of detecting the scanning position of the measurement light using the above-described moving scanning position detector.

  Therefore, the present invention is used in an imaging apparatus capable of capturing a high-resolution fundus image in a short time by detecting the position of the measurement light scanning position quickly and with high accuracy, an operation method of the imaging apparatus, and the imaging apparatus. An object of the present invention is to provide a scanning position detection device.

The present invention has the following configuration as one means for achieving the above object.
That is, according to the present invention, an imaging apparatus that scans measurement light on an inspection object and generates an image based on reflected light from the inspection object,
A scanning mechanism that scans the measurement light in a scanning range of the inspection object;
A light-shielding part that transmits or shields at least a part of the measurement light in an arbitrary region set corresponding to the scanning range;
A light detection unit for detecting at least part of the measurement light transmitted or reflected by the arbitrary region;
A state detector that detects a driving state of the scanning mechanism based on at least a part of the detected measurement light;
Image generation means for generating the image based on the reflected light and the detected driving state.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible by detecting the scanning position of measurement light quickly and with high accuracy, and a high-resolution fundus image can be captured in a short time.

It is a schematic diagram which shows the outline of a structure of the fundus imaging apparatus which concerns on the 1st Example of this invention. It is a figure explaining operation | movement of the scanning mechanism in the fundus imaging apparatus shown in FIG. It is a figure which shows the outline of a structure of the scanning position detection part used for the fundus imaging apparatus shown in FIG. It is a figure explaining the output obtained from the scanning position detection part shown in FIG. It is a figure explaining the change of the output in the period amplitude fluctuation | variation in a resonance mirror, Comprising: It is a figure which shows the output of the obtained pulse signal. It is a figure explaining the change of the output in the period amplitude fluctuation | variation in a resonance mirror, Comprising: It is a figure explaining the method of correct | amending the distortion of an image based on the output of a scanning position detection part. It is a figure explaining the change of the output in the period amplitude fluctuation | variation in a resonance mirror, Comprising: It is a figure explaining the method to measure the amplitude and period of the obtained pulse signal. It is a block diagram which shows the structure of the control part in the fundus imaging apparatus which concerns on the 1st Example of this invention. It is a flowchart which shows operation at the time of the image acquisition in the fundus imaging apparatus which concerns on 1st Example of this invention. It is a figure which shows the outline of a structure of the fundus imaging apparatus which concerns on the 2nd Example of this invention. It is a block diagram which shows the structure of the control part in the fundus imaging apparatus which concerns on the 2nd Example of this invention. It is a flowchart which shows operation at the time of the image acquisition in the fundus imaging apparatus concerning the 2nd example of the present invention. It is a figure which shows the outline of a structure of the fundus imaging apparatus which concerns on the 3rd Example of this invention. It is a figure which shows the outline of a structure of the scanning position detection part applied to the fundus imaging apparatus shown in FIG.

  Hereinafter, preferred embodiments to which the present invention is applied will be described in detail with reference to the accompanying drawings. The embodiments described below do not limit the present invention related to the scope of claims, and all combinations of features described in the present embodiments are essential to the solution means of the present invention. Not exclusively.

[First embodiment]
(Split light + Transmitted light type liquid crystal panel + PD)
First, a first embodiment of the present invention will be described. In this embodiment, the scanning position is detected by dividing the measurement light and detecting the timing at which one of the divided lights passes through a specific area masked with liquid crystal by a photodiode.

(Configuration of fundus imaging apparatus)
FIG. 1 is a diagram showing an outline of the configuration of the fundus imaging apparatus according to the first embodiment of the present invention. The fundus imaging apparatus according to the present embodiment includes a light source 101, a collimator lens 102, a first beam splitter 111, an adaptive optics system, a resonant mirror 106, a scanning mechanism, a third beam splitter 118, and eyepiece lenses 109 and 110. . The compensation optical system includes a second beam splitter 116, a reflection mirror 103, a wavefront correction element 104, and a reflection mirror 105. The scanning mechanism includes a resonance mirror 106, an offset galvanometer mirror 107, and a galvanometer mirror 108.

  Laser light that is measurement light emitted from the light source 101 is adjusted to parallel light by the collimator lens 102. After the adjustment, the light passes through the two galvanometer mirrors and is guided to the scanning mechanism via the reflection mirror 103, the wavefront correction element 104, and the reflection mirror 105. In the scanning mechanism, first, the laser beam is scanned by the resonance mirror 106 in the main scanning direction (x-axis direction) symmetrically about the rotation axis of the resonance mirror. Next, the offset galvanometer mirror 107 adds an offset in the main scanning direction (x-axis direction) to the center position where the resonant mirror scans the laser beam. Thereafter, the galvano mirror 108 scans the laser light in the sub-scanning direction (y-axis direction).

  It should be noted that the time required for imaging can be shortened as the cycle of these mirrors repeatedly scanning is shorter. Therefore, it is desirable to arrange small and light mirrors that operate at high speed close to each other. Laser light that is two-dimensionally scanned by the scanning mechanism as described above is applied to the eyeball 121 of the subject through the eyepiece lens 109 and the eyepiece lens 110.

  Laser light emitted to the fundus through the cornea of the eyeball 121 and the crystalline lens is reflected and scattered by the fundus of the subject's eye. The laser beam that has been reflected or the like is separated from the optical path of the measurement light after being returned by the first beam splitter 111 along the path that has entered as reflected light. The separated reflected light passes through the light receiving lens 112 and is converted into an electric signal corresponding to the intensity by the photodiode 113. The converted signal is input to the control unit 114. The signal is appropriately processed by the control unit 114 and then displayed as a fundus image on the monitor 115 or recorded as image data on a recording device (not shown).

  The second beam splitter 116 splits the reflected light from the fundus and guides the split light to the wavefront measuring element 117. As the wavefront measuring element, a Shack-Hartmann sensor or the like is used, and the state of the wavefront that changes depending on the crystalline lens or cornea of the human eye is sequentially measured. The measured wavefront is converted into a wavefront correction amount by being appropriately processed by the control unit 114 and output to the wavefront correction element 104.

  As the wavefront correction element, an optical phase modulator (SLM: Spatial Light Modulator) using LCOS (Liquid Crystal on Silicon) or the like is used. The wavefront correction element 104 adjusts the wavefront of the reflected light in accordance with the wavefront correction amount obtained from the control unit 114, so that the wavefront aberration of the human eye is compensated. By introducing these adaptive optical systems, aberrations occurring in the eye to be examined can be reduced, and as a result, a fundus image obtained by imaging photoreceptor cells on the fundus with a resolution of several μm can be obtained.

  The measurement light that is two-dimensionally scanned by the resonance mirror 106, the offset galvanometer mirror 107, and the galvanometer mirror 108 is split by the third beam splitter 118. A part of the divided measurement light is guided to the scanning position detection unit 119, and the other is guided to the eyeball (eye to be examined) 121. The scanning position detector 119 outputs a signal that changes with time according to the scanning position used for detection of the position of the scanning light by a method described later. Based on this signal, the control unit 114 starts data acquisition of the amount of reflected light from the photodiode 113. In addition to this, the control unit 114 sets an imaging region based on an input from the operation unit 120, controls driving of the light source 101, the resonant mirror 106, the offset galvano mirror 107, and the galvano mirror 108, or starts / stops measurement. The process is also executed.

(Description of scanning mechanism)
The operation of the scanning mechanism will be described with reference to FIG. FIG. 2A shows the change over time of the scanning position of the measurement light driven in the main scanning direction by the resonance mirror 106. In the figure, the vertical axis indicates the scanning position of the measurement light, and the horizontal axis indicates time. As shown in the figure, the resonant mirror 106 vibrates with a certain horizontal period tH, and scans the measurement light in a sine wave shape with the amplitude of the main scanning range H set by the control unit 114.

  FIG. 2B shows a temporal change in the scanning position of the measurement light driven in the sub-scanning direction by the galvanometer mirror 108. The galvanometer mirror 108 operates so as to gradually change the sub-scanning position in accordance with the reciprocal scanning of the measurement light by the resonance mirror 106. That is, the sub-scanning position is increased stepwise by shifting the sub-scanning by one line at the timing when the main scanning direction changes from the forward path to the backward path or from the backward path to the forward path. After the sub-scanning position reaches the other end of the width of the sub-scanning range V set by the control unit 114, it returns linearly to the sub-scanning start position again and operates in a sawtooth waveform with a vertical period tV.

  FIG. 2C shows the trajectory of the measurement light at the fundus scanned by the resonance mirror 106 and the galvanometer mirror 108. As shown in the figure, the galvanometer mirror 108 is controlled so that the odd-numbered line and the even-numbered line are scanned on the forward path and the return path when the resonant mirror 106 is reciprocating. The imaging region 201 is input from a doctor or the like via the operation unit 120, and a scanning range based on the set values (imaging width w and imaging height h) is calculated by the control unit 114. The main scanning range H in which the resonance mirror 106 scans the measurement light with the fundus is set wider than the imaging width w of the fundus image to be actually acquired. Further, the offset amount X0 can be added to the center position of the region where the resonance mirror 106 scans the measurement light by the galvanometer mirror 107. By adjusting the offset amount X0 and the offset amount Y0 by the galvano mirror 108, the measurement light can be scanned around an arbitrary point (X0, Y0) of the fundus.

  In this embodiment, the resonance mirror is used for scanning the measurement light in the main scanning direction, but the scanning mode in the main scanning direction is not limited to this. A method of deflecting light by rotating a polygon mirror used in a laser beam printer or the like may be used. Alternatively, a galvanometer mirror may be used for scanning in the main scanning direction. In general, the use of a resonance mirror has advantages in that the apparatus can be downsized and the frequency of main scanning can be increased rather than rotating a polygon mirror.

(Configuration of Scanning Position Detection Unit) (Description of Liquid Crystal Filter)
FIG. 3 is a schematic diagram showing an outline of the configuration of the scanning position detector 119. The scanning position detection unit 119 includes a condenser lens 301, a liquid crystal filter 302, a light receiving lens 303, and a photodiode 304.

  As shown in FIG. 3A, the measurement light divided by the third beam splitter 118 is imaged on the liquid crystal filter 302 through the condenser lens 301. The transmission and light shielding regions of the liquid crystal filter 302 are set by the control unit 114, and the light transmitted through the transmission region is collected by the light receiving lens 303 and the amount of light is measured by the photodiode 304. A signal relating to the amount of light obtained in the photodiode 304 as a result of the measurement is output to the control unit 114. The signal is converted into information related to the operation of the resonant mirror 106 in the control unit 114 and then used for various controls or processes.

  FIG. 3B shows a schematic configuration of the liquid crystal filter 302 using a top view and a cross-sectional view. The liquid crystal filter 302 includes a liquid crystal molecule 306 sealed between a pair of glass substrates 305, a transparent electrode 307 disposed on one side of the glass substrate 305, and a polarizing filter 308 disposed on the outside of the glass substrate 305. Has been.

  In the liquid crystal filter 302, the orientation of the liquid crystal molecules 306 located in a specific pixel can be changed by applying a voltage to the specific transparent electrode 307. Therefore, the polarization of light transmitted through the liquid crystal filter 302 can be controlled by controlling the orientation of the liquid crystal molecules 306 for each pixel by applying a voltage. On the other hand, the polarization filter 308 is disposed so as to transmit only vertical or horizontal polarized light. Therefore, if the polarization of the light transmitted through the liquid crystal is aligned, the light can be transmitted through the liquid crystal filter 302, and if it is arranged vertically, the light can be selected to be blocked.

  In addition, these electrodes, liquid crystal molecules, and corresponding pixels are arranged two-dimensionally. Therefore, the control unit 114 sets the light-shielding region 309 (P0, Q0, w ′, h ′) corresponding to the imaging region 201 and the transmission region 310 by individually controlling the transmission and light-shielding of each pixel.

  In this embodiment, a liquid crystal filter is used as a component that transmits and blocks light. However, this can be replaced by other configurations in which the same transmission and light shielding regions can be arbitrarily set. For example, in addition to the liquid crystal filter, a two-dimensional transmission or light shielding region may be formed by using a DMD (Digital Mirror Device) manufactured by using a micro electro-mechanical system (MEMS) technique.

(Position detection method)
The output of the scanning position detection unit 119 will be described with reference to FIG. As shown in FIG. 4A, a light shielding area 309 corresponding to the imaging area 201 is set in the liquid crystal filter 302, and the measurement light is scanned two-dimensionally in the same manner as the fundus. Therefore, as shown in the waveform of FIG. 4B, the photodiode 304 is shielded from the voltage i ₁ when it passes through the liquid crystal filter 302 according to the position on the liquid crystal filter 302 irradiated with the measurement light from the photodiode 304. Voltage i ₀ at the time of output is alternately output. The resonant mirror 106 maintains symmetrical sine wave vibration with a constant horizontal period tH. Therefore, basically, a pulse signal corresponding to this cycle is output. In addition, when the behavior of the resonant mirror 106 changes due to air resistance or other mechanical factors, the width and cycle of the output pulse signal change according to the fluctuation.

(For fluctuations in behavior)
When the behavior of the resonant mirror 106 changes due to air resistance or other mechanical factors, it is necessary to acquire a fundus image at an appropriate timing corresponding to this change. For this purpose, it is necessary to detect the timing at which scanning of the imaging region starts when the scanning light reaches the end of the imaging region. Specifically, the state in which the measurement light moves from the transmission region on the liquid crystal filter 302 to the light shielding region and the amount of light detected by the photodiode 304 decreases is detected. The trailing edge of the pulse signal obtained from the photodiode 304 may be detected, and based on this, the control unit 114 may start acquiring an image. From the obtained pulse signal, as shown in the waveform of FIG. 5A, a positive timing signal that becomes active at the falling edge is generated.

  When the measurement light is scanned on the fundus using the resonance mirror 106, the irradiation position draws an orbit close to a sine wave. Accordingly, when the reflected light is obtained pixel by pixel at a certain sampling frequency interval and displayed as an image in a linear pixel space, an image distorted in the main scanning direction is obtained. That is, the image near the center where the scanning speed of the laser beam is fast becomes an image that is roughly compressed, and the image near the both ends where the scanning speed is slow becomes an image that the sampling is finely stretched. It is necessary to correct and display.

A method of correcting image distortion based on the output of the scanning position detection unit will be described with reference to FIG. When the resonant mirror vibrates with a constant period and amplitude, image distortion may be corrected with parameters according to predetermined conditions. However, when the behavior of the resonant mirror changes, the period and amplitude also change, so it is necessary to change the image correction parameters. As the main mirror behavior change,
1 When the amplitude is increased: Since the time passing through the transmission region becomes longer, the width of the pulse spreads symmetrically.
2 When the amplitude is reduced: Since the time passing through the transmission region is shortened, the width of the pulse is narrowed symmetrically.
3 When the period is shortened: Since the timing of passing through the transmission region is advanced, the phase of the pulse advances.
4 When the period becomes longer: The timing of passing through the transmission region is delayed, so the phase of the pulse is delayed.
Is mentioned.

  When correcting an image, it is possible to calculate more accurate distortion correction parameters by extracting these features and their amounts from the actually measured pulse signal and measuring the actual amplitude and period of the resonant mirror. When measuring the amplitude and period, as shown in FIG. 5 (c), it is calculated how much the left and right edges of the measured pulse are shifted from each other (tL and tR) with respect to the center of the reference pulse. It ’s fine.

  In this embodiment, since one large rectangular shape is arranged in the center as the light shielding region, the pulse signal is generated once for one main scan. However, the shape of the light shielding region is not limited to this, and a plurality of pulse signals may be generated for one scan by arranging a striped light shielding region. Since more detailed behavior of the scanning light can be measured by calculating the interval between the plurality of pulse signals, the light shielding region may be set at an arbitrary position and shape in accordance with the image correction algorithm.

(Control block)
FIG. 6 shows a detailed configuration of the control unit 114 in a block diagram.
The wavefront measurement result output from the wavefront measuring element 117 is input to the wavefront acquisition unit 601, and then the wavefront correction amount calculation unit 602 calculates the wavefront correction amount. The calculated wavefront correction amount is output to the wavefront correction element 104 by the wavefront control unit 603.

  The operation unit 120 is an input terminal equipped with a GUI or the like, and performs imaging such as the center position (X0, Y0), the size of the imaging area (w, h), the start / stop of imaging, etc. Information is entered. The input imaging information is set by the scanning range setting unit 605 and the device control unit 606 via the operation communication unit 604 according to the application.

  Based on the set imaging range and imaging center position, the scanning range setting unit 605 sets a setting value required for measurement light scanning of horizontal scanning control and vertical scanning control, and a setting required for detection of the scanning position of measurement light. Calculate the value. The set values calculated in this embodiment are (H, V, tH, tV, X0, Y0, P0, Q0, w ′, h ′), a horizontal scanning control unit 607, a vertical scanning control unit 608, and Each value is set in the scanning position control unit 609.

  The horizontal scanning control unit 607 drives the resonant mirror 106 and the galvanometer mirror 107 based on the set value. The vertical scanning control unit 608 drives the galvanometer mirror 108 based on the set value. The scanning position control unit 609 drives the scanning position detection unit 119 based on the set value.

  The scanning position acquisition unit 613 acquires the pulse signal detected by the scanning position detection unit 119. The obtained pulse signal has a feature amount calculated by a subsequent module. The timing detection unit 614 converts the pulse signal into the timing signal shown in FIG. 4B, and then outputs this to the reflected light amount acquisition unit 610. The timing signal is used to start acquiring the fundus reflection light amount output from the photodiode 113. The period amplitude calculation unit 615 calculates the scanning light scanning period and amplitude by the resonant mirror 106 by calculating the edge position of the actually measured pulse signal illustrated in FIG. Data regarding these periods and amplitudes are used as correction parameters when image distortion correction is executed.

  The stop detection unit 616 detects the stop state of the resonant mirror 106 by detecting that the level of the pulse signal has not changed during a certain period. A signal indicating the detected stop state is output to the light source controller 617 and used as a light emission stop signal of the light source controller 617. The light source control unit 617 controls the start and stop of light emission from the light source 101. In this embodiment, the stop detection unit 616 detects the stop of the resonant mirror 106. However, by detecting whether any of the signal level, amplitude, and period of the pulse signal is within the range, a stop signal is output by detecting a state to be stopped such as abnormal irradiation or abnormal scanning. Anyway.

  The apparatus control unit 606 drives the stop detection unit 616, the light source control unit 617, the reflected light amount acquisition unit 610, and the image correction processing unit 611 according to the input measurement start or stop instruction. The acquired image corrected by the image correction processing unit 611 is output to the monitor 115 through the monitor control unit 612.

(Control flow)
FIG. 7 shows a flow of a series of operations from control of the scanning mechanism to image acquisition and display performed based on an input from the operation unit 120.

  In step S <b> 701, first, an imaging region on the fundus is input from the operation unit 120 by an operation of a doctor or the like. In step S <b> 702, the information is acquired by the control unit 114 through the operation communication unit 604. Based on these pieces of information, the scanning range setting unit 605 calculates the scanning range of each mirror corresponding to the imaging region, and sets the above-described setting values in the horizontal scanning control unit 607 and the vertical scanning control unit 608, respectively. At the same time, a light shielding area of the liquid crystal filter necessary for detecting the scanning position is also calculated, and the calculated set value is set in the scanning position control unit 609. When the setting is completed, scanning of laser light (measurement light) by each mirror is started in S703, and driving of the scanning position detection unit 119 is started in S704.

  After the driving is started, an apparatus preparation unit 606 issues a measurement light irradiation preparation instruction by the light source 101 in step S706. In step S <b> 707, the scanning position acquisition unit 613 starts acquiring the pulse signal in the scanning position detection unit 119. However, at this time, the apparatus control unit 606 has not issued an instruction to irradiate the laser beam from the light source 101, and no pulse signal is output from the scanning position detection unit 119 because there is no irradiation light. Accordingly, in S707, the stop detection unit 616 starts detecting the stop of the emission of light from the light source 101. That is, when there is no light source irradiation instruction from the device control unit 606, the stop detection unit 616 outputs a state of stop detection = 0.

  Through the above steps, the preparation for laser light irradiation is completed, and light source irradiation is possible. Therefore, an instruction to start imaging can be given from the operation unit 120, and an instruction to start imaging is input from the operation unit 120 by the operation of a doctor or the like in the next S708. In response to the input of the imaging start instruction, instructions are sequentially given to the apparatus control unit 606 in step S709 and subsequently to the light source control unit 617 in step S710 so that the laser light from the light source 101 is output. Subsequently, in S711, the irradiation start is set for the stop detection unit 616, and the laser light of the light source 101 is output.

  When the laser beam is output, a pulse signal is output by the scanning position detection unit 119. Therefore, in S712, the stop detection unit can detect the operation stop of each mirror. From this point of time, the stop detection unit always monitors the operation of the mirror, and when stop is detected, the stop detection unit immediately operates to issue an instruction to stop irradiation to the light source control unit 617 in S713.

  While the mirror is operating, the timing signal is detected by the pulse signal output from the scanning position detector 119 in S714. The reflected light amount acquisition unit 610 sequentially acquires the light amount from the photodiode 113 based on the timing signal output from the timing detection unit 614 in S716. In S715, the period amplitude calculation unit 615 calculates the period and amplitude in the scanning of the measurement light from the pulse signal. In step S <b> 717, the image correction processing unit 611 corrects the image acquired by the reflected light amount acquisition unit 610 based on the information calculated by the periodic amplitude calculation unit 615. The corrected image data is output to the monitor 115 in S718.

  In the present embodiment, in S719, the operations from the acquisition of the reflected light amount to the display on the monitor are repeatedly executed until an imaging stop instruction is input from the operation unit 120. However, the repetition may not be performed. The corrected image data may be stored in a recording device or the like. When an instruction to stop imaging is received in S719, the apparatus controller 606 stops laser light irradiation in S720, and each mirror stops in S721.

[Second Example]
(tracking)
FIG. 8 is a diagram showing a schematic configuration of a fundus imaging apparatus according to the second embodiment of the present invention, and FIG. 9 is a block diagram showing a detailed configuration of the control unit 803 in this embodiment. FIG. 10 is a diagram showing a flow of a series of operations from control of the scanning mechanism to image acquisition and display in this embodiment. In these drawings, the same components as those in the first embodiment shown in FIGS. 1 to 7 are denoted by the same reference numerals, and the description thereof is omitted here.

  In the first embodiment, the method for detecting the scanning position by setting the light shielding area of the liquid crystal filter for the imaging area designated by the doctor or the like has been described. In the present embodiment, a method of detecting the movement of the eyeball in addition to the designation from the doctor or the like and dynamically changing the scanning range and the light shielding area following the movement will be described.

(Configuration of fundus imaging apparatus)
FIG. 8 is a diagram showing a schematic configuration of a fundus imaging apparatus according to the second embodiment of the present invention. Since the AO-SLO image acquired by the fundus imaging apparatus described in the first embodiment has a high resolution, the imaging range (viewing angle) cannot be widened. For this reason, it is not suitable for the purpose of detecting the movement of the eyeball. Therefore, in this embodiment, a configuration including a dichroic mirror 801 and a motion detector 802 is added to these configurations, so that the movement, movement amount, or movement direction of the eyeball can be detected.

  A dichroic mirror is a special mirror that reflects only light of a specific wavelength and transmits light of other wavelengths. Therefore, since light of different wavelengths can be irradiated to the fundus from different paths, the motion detector 802 that uses light of a wavelength different from that of the measurement light obtained from the light source 101, and an AO using the measurement light -Simultaneous operation with SLO is possible. As the motion detector 802, an ordinary SLO that does not include a compensation optical system can be used. Therefore, a wide range fundus image is acquired by using another scanning light source or photodiode (not shown) as the light source.

  In the present embodiment, the entire fundus is imaged by SLO, and the position of a feature point (blood vessel or the like) is detected, so that the movement of the eyeball due to fixation eye movement or the movement amount when moving can be calculated. The control of the motion detector 802 and the eyeball motion detection are executed by the control unit 803, and the galvanometer mirrors 107 and 108 are controlled based on the obtained movement amount and movement direction of the eyeball. In this way, the imaging range on the fundus in the first designated AO-SLO or the like is maintained. In addition, the light-blocking area of the scanning position detection unit 119 is also changed according to the amount of movement of the eyeball, etc., so that an accurate scanning position is detected. Note that a fundus camera or an anterior eye camera may be used as the motion detector instead of the SLO.

(Control block)
FIG. 9 is a block diagram illustrating a detailed configuration of the control unit 803 in the present embodiment. In this embodiment, the motion detection control unit 901 and the movement amount calculation unit 902 are different from the control unit 114 in the first embodiment.

  The motion detection control unit 901 controls the motion detector 802 to acquire a wide range of fundus images. The movement amount calculation unit 902 calculates the position of each feature point from the acquired plurality of fundus images, and calculates the movement amount (ΔX, ΔY) of the eyeball by calculating the change amount of these positions. The calculated movement amount is set in the horizontal scanning control unit 607 and the vertical scanning control unit 608, and the fundus image following the movement of the eyeball can be acquired by changing the center point (X0, Y0) of the imaging region 201. Further, the movement amount is also set in the scanning position control unit 609, and the center point (P0, Q0) of the light shielding region 309 of the scanning position detection unit 119 is set in the movement amount and the movement direction corresponding to the movement amount of the previous center point. Change accordingly. This makes it possible to detect the scanning position accurately and quickly even when the imaging region changes due to the movement of the eyeball.

  The above-described dichroic mirror 801, motion detector 802, motion detection control unit 901, and movement amount calculation unit 902 constitute a motion detection unit that determines the amount and direction of movement of the eye to be examined. The motion detection unit configures the tracking mechanism in the present embodiment together with the configuration in which the center point of the scanning position is changed according to the obtained motion to change the arrangement of the scanning range. Further, the control unit 114 changes an arbitrary region in the liquid crystal filter 302 according to the arrangement of the scanned scanning range.

(Control flow)
FIG. 10 shows a flow of a series of operations in the present embodiment.
First, in S1001, an instruction to start motion detection is input from the operation unit 120 by an operation of a doctor or the like. This instruction is notified to the motion detection control unit 901 via the operation communication unit 604, and driving of the motion detector 802 is started in S1002. The fundus image output from the motion detector 802 in S1003 is sequentially input to the movement amount calculation unit 902 via the motion detection control unit 901. In step S1004, the movement amount calculation unit 902 detects the positions of the feature points of the sequentially input images, and how much the position of the feature point of the next image has moved with respect to the previous image (movement amounts ΔX and ΔY). ) Is calculated.

  In step S1005, the calculated movement amount is output to the horizontal scanning control unit 607, the vertical scanning control unit 608, and the scanning position control unit 609, and the center positions of the imaging region and the light shielding region are corrected based on the movement amount. . These operations are always executed, and the state in which the scanning range and the scanning position detection follow in accordance with the movement of the eyeball due to the fixation micromotion or the like is maintained until a stop is instructed from the operation unit 120 in S1006. Thereafter, the fundus image is acquired and displayed according to the flow shown in FIG. 7 of the first embodiment of S701 to S721.

  Since the eyeball of the human body also has fine eye movement vibration called fixation fixation micromotion, it is very difficult to dynamically move the place where the scanning position is detected following these quick movements. According to the present embodiment, even in such a case, it is possible to arrange an arbitrary transmission region in the liquid crystal filter 302, and it is possible to detect the scanning position following the movement of the eye to be examined. .

[Third embodiment]
(Reflective liquid crystal filter)
FIG. 11 is a diagram showing a schematic configuration of a fundus imaging apparatus according to the third embodiment of the present invention, and FIG. 12 is a diagram showing a schematic configuration of a scanning position detection unit in the present embodiment. It is the figure which showed the scanning position detection method. In these drawings, the same components as those in the first and second embodiments are denoted by the same reference numerals and the description thereof is omitted here.

  In the first and second embodiments, the method of detecting the scanning position of the measurement light using the transmission type liquid crystal filter in the scanning position detection unit 119 has been described. In this embodiment, a configuration for detecting a scanning position of measurement light using a reflective liquid crystal filter will be described.

(Configuration of fundus imaging apparatus)
As described above, FIG. 11 is a diagram showing an outline of the configuration of the fundus imaging apparatus according to the third embodiment of the present invention. In the configuration described in the first and second embodiments, the light scanned by the scanning mechanism is divided by the beam splitter 118, and the divided light is guided to the scanning position detector 119. In this embodiment, the configuration is such that the direct light is guided to the scanning position detection unit 1101 without dividing the scanning light, and there is an advantage that the number of optical components can be reduced.

(Configuration of Scanning Position Detection Unit) (Description of Liquid Crystal Filter)
FIG. 12 is a schematic diagram showing an outline of the configuration of the scanning position detection unit 1101. The scanning position detection unit 1101 includes a condenser lens 1201, a liquid crystal filter 1202, a reflection mirror 1205, and a collimator lens 1206.

  As shown in FIG. 12, the measurement light scanned by the scanning mechanism is imaged on the liquid crystal filter 1202 by the condenser lens 1201. As the reflection-type liquid crystal filter, a filter of a type that controls liquid crystal molecules by driving liquid crystal molecules in a dynamic scattering mode (DSM) and scattering incident light can be used. In the liquid crystal filter 1202, a transmission region 1203 and a light shielding region 1204 are set by the control unit 803.

  The measurement light transmitted through the transmission region 1203 is specularly reflected by the reflection mirror 1205 disposed on the back surface of the filter. The regularly reflected light is adjusted to parallel light by the collimator lens 1206 and guided to the eyeball 121. The measurement light reflected by the fundus is again transmitted through the transmission region 1203 of the liquid crystal filter 1202, reflected by the reflection mirror 1205, and guided to the photodiode 113.

  On the other hand, the measurement light incident on the light shielding region 1204 is scattered by the liquid crystal molecules in the liquid crystal filter 1202 before reaching the reflection mirror 1205. Part of the scattered light is collected on the photodiode 1208 by the light receiving lens 1207. When measurement light is applied to the light shielding region 1204 of the liquid crystal filter 1202, scattered light is generated, so that the output voltage of the photodiode 1208 increases.

  When measurement light is applied to the transmission region 1203, almost no scattered light is generated, and the output voltage of the photodiode 1208 is low. Therefore, by detecting the scattered light with the photodiode 1208, a pulse signal similar to that in the first embodiment can be output. That is, by detecting the scattered light, the control unit 803 can generate the timing signal and measure the periodic amplitude in the measurement light scanning.

  As described above, the present invention relates to an imaging apparatus that scans measurement light such as laser light on an inspection object exemplified by an eye and generates an image based on reflected light from the inspection object. The imaging apparatus mainly includes a scanning mechanism, a light shielding unit, a light detection unit, a state detection unit, and an image generation unit. The scanning mechanism includes a resonance mirror 106 and a galvanometer mirror 108, and scans the measurement light in a scanning range on the eye to be examined. The light shielding unit includes the liquid crystal filter 302 or the liquid crystal filter 1202, and transmits or blocks at least a part of the measurement light in an arbitrary region set corresponding to the scanning range. The scanning range is designated by the scanning range setting unit 605, and the setting of this arbitrary area is executed by the control unit 114.

  The light detection unit includes a photodiode 304 or a photodiode 1208, and detects at least a part of measurement light transmitted or reflected through an arbitrary region. In the first embodiment, the photodiode 304 detects a part of the light split as a part of the measurement light by the beam splitter 118 and further transmitted through the liquid crystal filter 302. In the third embodiment, the photodiode 1208 detects a part of the measurement light reflected by the light shielding region 1204 outside the transmission region 1203 corresponding to the scanning range on the eye to be examined. More specifically, the light detection unit is configured to transmit at least a part of the measurement light transmitted or reflected by the pulse shown in FIG. 4B or FIG. To detect changes.

  The state detection unit includes a scanning position acquisition unit 613, a timing detection unit 614, a periodic amplitude calculation unit 615, and a stop detection unit 616, and detects the driving state of the scanning mechanism based on at least a part of the detected measurement light. . The period amplitude calculation unit 615 calculates at least one of the period and the amplitude based on the detected temporal change. The timing detection unit 614 scans the measurement light at a predetermined position such as a start position where reception of reflected light starts in scanning of the measurement light during image acquisition based on the temporal change detected by the light detection unit. The timing to perform is detected. The stop detection unit 616 detects whether or not the measurement light is scanning the scanning range by the scanning mechanism based on the detected temporal change. When scanning is not performed, irradiation of the measurement light is stopped by the light source control unit 617 in the control unit 114.

  The image generation means includes a photodiode 113, a reflected light amount acquisition unit 610, and an image correction processing unit 611, and generates an image of the eye to be examined based on the reflected light from the eye to be examined and the detected drive state. At that time, the distortion generated in the image is corrected based on the period and amplitude in the measurement light scanning obtained by the period amplitude calculation unit 615.

  The present invention can also be understood as a scanning position detection device that detects the scanning position of measurement light in an imaging device. In this case, the scanning position detection device detects the scanning position of the measurement light on the object to be inspected based on at least a part of the measurement light detected by the light shielding unit and the light detection unit. As a device including

  As described above, according to the present invention, the accuracy and speed of scanning position detection are not limited by mechanical design constraints, and scanning position can be detected quickly and accurately following various imaging conditions. It becomes possible to do.

(Other examples)
In addition, although the embodiment using the AO-SLO is described in the above-described embodiment, the application target of the present invention is not limited to the AO-SLO. That is, the present invention can be applied to an imaging apparatus that scans measurement light such as SLO and OCT, and further, a combination of these imaging apparatus and other imaging apparatuses such as a visual field measuring instrument and an intraocular pressure measuring instrument, or a combination thereof. It can also be applied to. Moreover, the apparatus which consists of a combination about each of these ophthalmologic imaging apparatuses may be sufficient.

  In the above-described embodiments, the case where the object to be inspected is a human eye to be inspected is described. However, the present invention can also be applied to an object to be measured such as skin or organ other than the eye. In this case, the present invention has a mode as a medical imaging apparatus such as an endoscope other than the ophthalmologic apparatus. Therefore, it is desirable that the present invention is grasped as an imaging apparatus exemplified by an ophthalmologic apparatus, and the eye to be examined is grasped as one aspect of the object to be examined.

  Furthermore, the present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus execute the program. It can also be realized by a process of reading and executing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

DESCRIPTION OF SYMBOLS 101: Light source 102: Collimating lens 103, 105: Reflection mirror 104: Wavefront correction element 106: Resonance mirror 107, 108: Galvano mirror 109, 110: Eyepiece lens 111, 116, 118: Beam splitter 112: Light receiving lens 113: Photodiode 114, 803: Control unit 115: Monitor 117: Wavefront measuring element 119: Scanning position detection unit

Claims (20)

An imaging device that scans measurement light on an inspection object and generates an image based on reflected light from the inspection object,
A scanning mechanism that scans the measurement light in a scanning range of the inspection object;
A light-shielding part that transmits or shields at least a part of the measurement light in an arbitrary region set corresponding to the scanning range;
A light detection unit for detecting at least part of the measurement light transmitted or reflected by the arbitrary region;
A state detector that detects a driving state of the scanning mechanism based on at least a part of the detected measurement light;
An imaging apparatus comprising: the reflected light; and an image generation unit configured to generate the image based on the detected driving state. Means for designating the scanning range;
The imaging apparatus according to claim 1, further comprising: a control unit configured to set the arbitrary area according to the designated scanning range. The light detection unit detects a temporal change in the light amount of the measurement light transmitted or reflected or the position where the measurement light is transmitted or reflected,
The state detection unit detects a timing at which the scanning mechanism scans the measurement light at a predetermined position in the scanning range based on the detected temporal change,
The imaging apparatus according to claim 2, wherein the image generation unit starts receiving the reflected light for generating the image based on the detected timing. The state detection unit calculates at least a period or an amplitude in the scanning of the measurement light by the scanning mechanism based on the detected temporal change,
The imaging apparatus according to claim 3, wherein the image generation unit corrects distortion of the image based on at least the calculated period or amplitude. The state detection unit detects whether the scanning mechanism is scanning the scanning range with the measurement light based on the detected temporal change,
When the scanning is not performed, the measurement light irradiation is stopped.
The imaging apparatus according to claim 3 or 4, wherein Means for dividing a part of the measurement light disposed between the scanning mechanism and the inspection object;
The control unit causes the light shielding unit to set the arbitrary region that shields the measurement light within a region corresponding to the scanning range in the divided measurement light,
The imaging device according to claim 2, wherein the light detection unit detects at least a part of the measurement light transmitted outside the arbitrary region. Arranged between the scanning mechanism and the object to be inspected, and having means for reflecting the measurement light to the object to be inspected,
The control unit causes the light-shielding unit to set the arbitrary region that transmits the measurement light in a region of the reflecting unit corresponding to the scanning range of the inspection object,
The imaging device according to claim 2, wherein the light detection unit detects at least a part of the measurement light scattered by a light shielding unit outside the arbitrary region. The inspection object is an eyeball,
The tracking mechanism has a tracking mechanism that follows the movement of the eyeball in the arrangement of the scanning range in which the measurement light is scanned.
The imaging apparatus according to claim 2, wherein the control unit changes the arbitrary region in the light shielding unit according to the arrangement of the scanned scanning range. An operation method of an imaging apparatus that scans measurement light on an inspection object and generates an image based on reflected light from the inspection object,
The measurement light is scanned by a scanning mechanism in a scanning range of the inspection object,
In the light-shielding portion, at least a part of the measurement light is transmitted or shielded in an arbitrary region set corresponding to the scanning range,
Detecting at least part of the measurement light transmitted or reflected through the arbitrary region by a light detection unit;
A state detection unit detects a driving state of the scanning mechanism based on at least a part of the detected measurement light,
A method of operating an imaging apparatus, comprising: generating the image based on the reflected light and the detected driving state. Specify the scanning range,
The method of operating an imaging apparatus according to claim 9, further comprising: setting the arbitrary area according to the designated scanning range by a control unit. The light detection unit detects a temporal change in the light amount or the transmission or reflection position of at least part of the transmitted or reflected measurement light,
The state detection unit detects a timing at which the scanning mechanism scans the measurement light at a predetermined position in the scanning range based on the detected temporal change,
The method of operating an imaging apparatus according to claim 10, wherein reception of the reflected light for generating the image is started based on the detected timing. The state detection unit calculates at least a period or an amplitude in the scanning of the measurement light by the scanning mechanism based on the detected temporal change,
12. The method of operating an imaging apparatus according to claim 11, wherein distortion of the image is corrected based on at least the calculated period or amplitude. The state detection unit detects whether the scanning mechanism is scanning the scanning range with the measurement light based on the detected temporal change,
When the scanning is not performed, the measurement light irradiation is stopped.
The method of operating an imaging apparatus according to claim 11 or 12, A step of being arranged between the scanning mechanism and the object to be inspected and dividing a part of the measurement light;
The control unit causes the light shielding unit to set the arbitrary region that shields the measurement light within a region corresponding to the scanning range in the divided measurement light,
The method of operating an imaging apparatus according to claim 10, wherein the light detection unit detects at least a part of the measurement light transmitted outside the arbitrary region. A step of being disposed between the scanning mechanism and the inspection object and reflecting the measurement light to the inspection object;
The control unit sets the arbitrary region that transmits the measurement light in the region of the reflecting unit corresponding to the scanning range of the inspection object with respect to the light shielding unit,
The operation of the imaging apparatus according to claim 10, wherein the light detection unit detects at least a part of the measurement light scattered by a light shielding unit outside the arbitrary region. Method. The inspection object is an eyeball,
The tracking mechanism has a tracking mechanism that follows the movement of the eyeball in the arrangement of the scanning range in which the measurement light is scanned.
The operation of the imaging apparatus according to any one of claims 10 to 15, wherein the control unit changes the arbitrary region in the light shielding unit in accordance with the arrangement of the scanned scanning range. Method.   A program causing a computer to execute each step of the operation method of the imaging apparatus according to any one of claims 9 to 16. The measurement light is scanned in a scanning range on the inspection object by a scanning mechanism, and the measurement light in the imaging device that generates an image based on the scanning position of the measurement light and the reflected light of the measurement light from the inspection object A scanning position detection device for detecting a scanning position,
A light-shielding part that transmits or shields at least a part of the measurement light in an arbitrary region set corresponding to the scanning range;
A light detection unit for detecting at least part of the measurement light transmitted or reflected by the arbitrary region;
And a means for detecting a scanning position of the measurement light on the inspection object based on at least a part of the detected measurement light. Means for dividing a part of the measurement light, which is arranged between the scanning mechanism and the inspection object;
A control unit that sets the arbitrary region for shielding the measurement light within a region corresponding to the scanning range in the divided measurement light, with respect to the light shielding unit,
The scanning position detection apparatus according to claim 18, wherein the light detection unit detects at least a part of the measurement light transmitted outside the arbitrary region. Means disposed between the scanning mechanism and the inspection object to reflect the measurement light to the inspection object;
A control unit that sets the arbitrary region that transmits the measurement light in a region of the reflecting unit corresponding to the scanning range of the inspection object with respect to the light shielding unit;
The scanning position detection apparatus according to claim 18, wherein the light detection unit detects at least a part of the measurement light scattered by the light shielding unit outside the arbitrary region.

Images