JP5977541B2 - Scanning fundus imaging device - Google Patents

Description

  The present invention relates to an improvement of a scanning fundus imaging apparatus that constructs a fundus image by receiving reflected spot light from irradiation spot light from each part of the fundus while scanning the fundus with irradiation spot light.

  Conventionally, a scanning fundus imaging device (SLO) that constructs a fundus image by receiving reflected spot light from irradiation spot light from each part of the fundus while scanning the fundus with irradiation spot light is known (for example, (See Patent Document 1).

  This scanning type fundus imaging apparatus has a mirror that scans the fundus with irradiation spot light, and reciprocates the mirror to capture the fundus image during forward movement of the mirror and backward movement of the mirror. One that constructs a high-resolution fundus image at high speed is known.

  In this type of scanning fundus imaging apparatus, in order to synchronize the operation timing of the mirror that scans the fundus with irradiation spot light and the image construction unit that constructs a frame image as a fundus image, a synchronization signal output from the mirror drive circuit Is used as a trigger signal to determine the start timing of capturing the fundus image.

  In this type of scanning fundus imaging apparatus, in order to synchronize the timing of the fundus image captured by the forward movement of the mirror and the fundus image captured by the backward movement of the mirror on the mirror surface, the acquisition of the fundus image captured by the forward movement of the mirror is performed. The start timing signal and the acquisition start timing signal of the fundus image acquired by the backward movement of the mirror are generated while being electrically shifted by a half cycle with respect to one cycle of the vibration of the mirror.

JP 2011-212103 A

  By the way, the circuit for generating the synchronization signal of the mirror drive circuit is composed of, for example, an oscillator composed of a resistor and a coil. The oscillator has a temperature characteristic that its electrical characteristic changes depending on the environmental temperature, and the generation period of the synchronization signal changes depending on the temperature with respect to the vibration period of the mirror.

Therefore, even if the vibration period of the mirror is mechanically stable and constant in time, the synchronization signal output from the mirror drive circuit based on the vibration of the mirror varies with time.
Therefore, even if the mirror deflection angle position and the synchronization signal generation position are adjusted in one-to-one correspondence at a certain temperature, the correspondence between the mirror deflection angle position and the synchronization signal generation position when the temperature changes. The relationship changes.

  Therefore, the capture start timing with respect to the image shake angle in the forward direction of the mirror deviates from the image capture start timing with respect to the shake angle in the backward direction of the mirror. The image capture start position of the scanning in the direction cannot be matched only by electrical timing adjustment, and the fundus image obtained by scanning in the forward direction and the fundus image obtained by scanning in the backward direction are combined to form a frame. When the image is constructed, the frame image becomes discontinuous.

  In addition, since the displacement speed of the scanning mirror becomes slow in the vicinity of the maximum position of the scanning mirror deflection angle, the image resulting from the mirror deflection angle must be adjusted without any adjustment of the pixel clock interval for capturing the image. Aberration occurs.

  The present invention has been made in view of the above circumstances, and in particular, a scanning fundus imaging apparatus capable of constructing a high-resolution frame image by removing aberrations of an image caused by a mirror deflection angle. The purpose is to provide.

  A scanning fundus imaging apparatus of the present invention includes a fundus scanning optical system that scans the fundus while irradiating the fundus of the eye to be examined, an image receiving optical system that receives the irradiation spot light and outputs an image receiving signal, and an image receiving device. A fundus image constructing unit that constructs a fundus image using an image signal received from the optical system, the fundus scanning optical system includes a scanning mirror that scans the fundus in the vertical direction and the horizontal direction, and the scanning mirror is driven by a mirror. A mask that adjusts the generation interval of the pixel clock is provided at a position conjugate with the fundus at a position offset from the optical path of the fundus scanning optical system by reciprocating vibration between the forward direction and the backward direction by the circuit. The fundus image constructing unit adjusts the image capture interval with respect to the shake angle of the scanning mirror using the mask image.

  According to the present invention, there is an effect that it is possible to construct a high-resolution frame image by removing the aberration caused by the deflection angle of the mirror.

FIG. 1 is an explanatory diagram showing an example of an optical system of a scanning fundus imaging apparatus according to the present invention. FIG. 2 is an explanatory diagram schematically showing a fundus scanning state by irradiation spot light. FIG. 3 is a perspective view showing an example of the rotation drive mechanism. FIG. 4 is an explanatory diagram showing a fundus image acquired for each predetermined angle of the polarization axis of the irradiation spot light. FIG. 5 is an explanatory diagram showing a superposed fundus image formed by superposing the fundus image shown in FIG. FIG. 6 is a block diagram showing a main configuration of the fundus image construction unit in FIG. FIG. 7 is an explanatory diagram showing the relationship between the displacement angle and angular velocity of the resonant mirror shown in FIG. FIG. 8 is an explanatory diagram showing a shift between the image capture end position by scanning in the forward movement direction and the image capture start position by scanning in the backward movement direction caused by the shift of the vertical synchronization signal. FIG. 9 is an explanatory diagram showing the distortion of the fundus image acquired by the scanning of FIG. FIG. 10 is a plan view showing the shape of a mask provided in the fundus scanning optical system, and is an explanatory diagram showing a state where the mask provided at a position conjugate with the fundus is being scanned. It is the elements on larger scale which show the mask image obtained by the scanning of the mask of FIG. FIG. 12 is a plan view showing a state in which a mask provided in a plane conjugate with the fundus is scanned at a position offset from the optical path of the fundus scanning optical system. FIG. 13 is an explanatory diagram of the black line-shaped portion image acquired by the mask scanning shown in FIG. 12, and is an explanatory diagram showing an image before adjusting the generation interval of the pixel clock signal. FIG. 14 is an explanatory diagram of the black line-shaped portion image acquired by the mask scanning shown in FIG. 12, and is an explanatory diagram showing the image after adjusting the generation interval of the pixel clock signal. FIG. 15 is a timing chart showing the timings of the system clock signal, pixel clock signal, ADC output data, and write data to the image memory. FIG. 16 is a conceptual diagram showing a comparison between a pixel clock signal before adjusting the generation interval and a pixel clock signal after adjusting the generation interval.

In the following, the outline of the configuration and operation of the optical system of the scanning fundus imaging apparatus according to the present invention will be described, and then the detailed configuration of the embodiment of the scanning fundus imaging apparatus according to the present invention will be described.
(Overview of configuration and operation of scanning fundus imaging apparatus)
In FIG. 1, 1 is a fundus scanning optical system, 2 is a shared optical system, 3 is an image receiving optical system, and 4 is a fundus image construction unit. The fundus scanning optical system 1 includes a laser light source unit 5. The laser light source unit 5 includes a laser light source 6, a collimating lens 7 that condenses the laser light P emitted from the laser light source 6 and converts it into a collimated light beam, and a polarizing plate 8.

The polarizing plate 8 has a function of passing linearly polarized (P-polarized) laser light that vibrates in a specific direction out of the laser light emitted from the laser light source unit 5.
The shared optical system 2 is shared by the fundus scanning optical system 1 and the image receiving optical system 3, and is focused on the beam splitter 9, the scanner 10, the half-wave plate 11, the relay lens 12, and the reflection mirror 13. It has a lens 14 and an objective lens 15. The scanner 10 includes, for example, a resonant mirror 10a and a galvano mirror 10b.

  The beam splitter 9 cooperates with the polarizing plate 8 and the polarizing plate 19 described later to pass the laser light P having linearly polarized light and has linearly polarized light in a direction parallel to the direction of linearly polarized light of the laser light P. It functions as a polarization beam splitter that blocks the passage of reflected light and permits the passage of reflected spot light having linearly polarized light in a direction orthogonal to the direction of linearly polarized light of laser light P.

The scanner 10 plays a role of scanning the fundus oculi Ef of the eye E to be examined as shown in FIG. In that Figure 2, Ep papillary, Eb blood vessels, Eo represents the macula lutea, V _H is the scanning in the vertical direction by the laser spot light SP, H _V denotes the horizontal scanning by the laser spot light SP.

The resonant mirror 10a is used for scanning the fundus oculi Ef in the vertical direction, and the galvano mirror 10b is used for scanning the fundus oculi Ef in the horizontal direction.
The half-wave plate 11 plays a role of rotating the polarization axis of the P-polarized laser beam P. When the half-wave plate 11 is rotated by θ degrees, the polarization axis of the P-polarized laser beam P is rotated by 2θ degrees. To do.

  3 shows the rotational drive mechanism of the half-wave plate 11. In FIG. 3, 16 is a geared stepping motor, 17 is a small-diameter gear, 18 is a large-diameter gear, and 18 'is the rotation of the large-diameter gear 18. Is the axis. The half-wave plate 11 is attached to the rotation shaft 18 ′ and rotated by the small diameter gear 17 and the large diameter gear 18.

  The geared stepping motor 16 has a role of step-rotating the half-wave plate 11 by a predetermined angle. Here, the half-wave plate 11 is rotated every 15 degrees and rotated by 15 degrees. An angle timing signal is output to the fundus image construction unit 4 every time.

  The focusing lens 14 and the objective lens 15 serve as a focusing optical system that forms the irradiation spot light SP on the fundus oculi Ef of the eye E to be examined. The reflected spot light from the fundus oculi Ef is collected by the objective lens 15 and guided to the beam splitter 9 through the focusing lens 14, the reflection mirror 13, the relay lens 12, the half-wave plate 11, and the scanner 10.

  The reflected spot light from the fundus oculi Ef includes S-polarized component light as well as P-polarized component light due to the birefringence of the fundus oculi Ef. The reflected spot light from the fundus oculi Ef is reflected by the beam splitter 9 and guided to the image receiving optical system 3.

  The image receiving optical system 3 includes a polarizing plate 19, an imaging lens 20, a confocal stop 21, and an image receiver 22. The polarizing plate 19 plays a role of transmitting S-polarized light as linearly polarized light orthogonal to the P-polarized light. The receiver 22 receives S-polarized reflected spot light, and the received signal is input to an image processing unit 23 described later.

  The confocal stop 21 is disposed at a conjugate position with the fundus oculi Ef of the eye E when the fundus oculi Ef is in focus, and the cornea Ec of the eye E is a point Q1 ′ on the optical path between the scanners 10. And conjugate. The fundus oculi Ef is conjugate with the point Q1 ″ on the optical path of the shared optical system 2, and the fundus oculi image of the fundus oculi Ef is once formed in the air in a plane including the point Q1 ″.

  The fundus oculi image construction unit 4 is schematically composed of an image processing unit 23, a storage unit 24, and an operation unit 25. The image processing unit 23 acquires one fundus image Ef ′ shown in FIG. 4 for each predetermined angle (every 15 degrees) of the half-wave plate 11 based on the angle timing signal, and this fundus image Ef ′ is obtained. Processing to be stored in the storage unit 24 is performed.

  Next, the image processing unit 23 counts the number of angle timing signals, for example, and constructs one superimposed fundus image Ef ″ shown in FIG. 5 for every 90 ° rotation of the half-wave plate 11. .

  For example, FIGS. 4A to 4F show a total of six fundus images Ef obtained by rotating the half-wave plate 11 by θ = 15 degrees (the polarization axis is rotated by 30 degrees). It is a schematic diagram showing '.

  In FIG. 4A to FIG. 4F, the portion where the halftone dot density is high is the low luminance portion of the fundus image Ef ′, and the portion where the halftone dot density is low is the portion of the fundus image Ef ′. Among them, it is a part with high brightness.

  As shown in FIGS. 4A to 4F, the unevenness of luminance exists in each fundus image Ef ′ due to the birefringence of the fundus oculi Ef. Due to the rotation of the polarization axis of the irradiation spot light SP, the state of luminance unevenness at each part of the fundus image Ef ′ is changed.

  The image processing unit 23 counts the number of angle timing signals, reads out each fundus image Ef ′ from the storage unit 24 for each rotation angle of the half-wave plate 11 corresponding to 180 ° rotation of the polarization axis, By superimposing the fundus oculi image Ef ′ shown in FIGS. 4A to 4F, one superimposed fundus oculi image Ef ″ from which luminance unevenness and ghost are removed is constructed as shown in FIG.

(Details of Examples)
The scanning mirror 10 is driven by a mirror driving circuit 30 as shown in FIG. The mirror drive circuit 30 includes a resonant mirror drive circuit 30a and a galvanometer mirror drive circuit 30b.

  The resonant mirror 10a is reciprocated 4000 times per second by the resonant mirror drive circuit 30a, for example. That is, the vibration frequency of the resonant mirror 10a is 4 KHz, and the irradiation spot light SP is reciprocally scanned in the vertical direction. For the structure of the resonant mirror 10a, see, for example, JP-T-2009-541784.

FIG. 7 is an explanatory view showing the relationship between the displacement angle of the resonant mirror 10a and the angular velocity corresponding to one period of driving of the resonant mirror 10a, the vertical axis is the displacement angle of the resonant mirror 10a, and the horizontal axis is It's time.

  In FIG. 7, the positive maximum shake angle position of the resonant mirror 10a is set to “0” on the time axis, and the time until the resonant mirror 10a returns to the original maximum shake angle position is set to “T”. Time is shown as the negative maximum deflection angle position of the resonant mirror 10a.

  The resonant mirror drive circuit 30a includes, for example, an oscillator composed of a resistor and a coil. This oscillator outputs a vertical synchronization signal SYNC for each oscillation period of the resonant mirror 10a. FIG. 7 shows that the vertical synchronization signal SYNC is output at the position on the time axis corresponding to the vicinity of the positive maximum deflection angle position of the resonant mirror 10a.

  The resonant mirror 10a reciprocates without being controlled from the periphery, and as a means for notifying external peripheral devices and peripheral circuits of the operating state, the resonant mirror 10a outputs the vertical synchronization signal SYNC at a timing when it reaches a certain swing angle. Output. Thus, as indicated by arrows A1 to An shown in FIG. 2, scanning in the forward movement direction is performed on the fundus oculi Ef by the irradiation spot light SP.

  The period of the vertical synchronization signal SYNC changes depending on the environmental temperature even if the mechanical vibration period of the resonant mirror 10a is constant because of the resistance temperature characteristic of the oscillator. However, here, for convenience of explanation, the period of the vertical synchronization signal SYNC will be described assuming that the environmental temperature is constant.

  The vertical synchronization signal SYNC is input to the column counter 31 and the pixel clock generation circuit 32 as shown in FIG. The column counter 31 counts the number of vertical synchronization signals SYNC, outputs a position signal to the galvanomirror driving circuit 30b every half cycle of the vertical synchronization signal SYNC, and also generates a combined synchronization signal generation circuit 33 and a write address generation circuit. And a horizontal synchronizing signal SYNC ′. When the horizontal synchronization signal SYNC 'is output, the resonant mirror 10a is mechanically rotated in the backward movement direction.

  The galvano mirror 10b is rotated by a predetermined angle in the horizontal direction every time the vertical synchronization signal SYNC is input to the column counter 31 and the position signal is updated. At this time, since the resonant mirror 10a is rotated in the backward movement direction, as indicated by arrows B1 to Bn shown in FIG. 2, scanning in the backward movement direction is performed on the fundus oculi Ef by the irradiation spot light SP. Is done. The column counter 31 corresponds to each column, and the row counter 35 corresponds to the pixels of each column.

  Note that the angular velocity of the resonant mirror 10a is reduced in the vicinity of the maximum deflection angle, so the displacement angle curve Q1 has a shape similar to a sine curve.

  The pixel clock generation circuit 32 outputs a pixel clock signal PL as a timing signal to the row counter 35 and the analog / digital conversion circuit (ADC) 36 based on the vertical synchronization signal SYNC.

  Here, the number of pixel clock signals PL is 1536, and the number of pixel clock signals PL corresponds to the number of dots of pixels. That is, it corresponds to 0 to 1535 addresses in the image memory described later.

  The generation start position of the pixel clock signal PL is set to a position for a predetermined time from the vertical synchronization signal SYNC and the horizontal synchronization signal SYNC ', and the displacement angle curve Q1 of the resonant mirror 10a is a position where it changes linearly. The generation start position of the pixel clock signal PL is determined by using, for example, a system clock signal, and the frequency of the system clock signal is several times larger than the frequency of the pixel clock.

  The row counter 35 counts the number of pixel clock signals PL and outputs the count signal to the write address generation circuit 34 and the composite synchronization signal generation circuit 33. The write address generation circuit 34 outputs a write control signal WL to the arbitration circuit 37 every time the pixel clock signal PL is input.

  The arbitration circuit 37 has a function of performing write / read / stop control adjustment, and the read control signal RL is input to the arbitration circuit 37 from the read address generation circuit 38. The arbitration circuit 37 outputs an address (address) signal and an R / W signal to the image memory 39.

  The analog-to-digital conversion circuit (ADC) 36 receives the image reception signal from the image receiver 22 and converts the image reception signal from analog to digital each time the pixel clock signal PL is input. The digital data is input to the image memory 39, and the digital data is written to an address corresponding to the pixel clock signal PL of the image memory 39. That is, pixel information in units of dots is written in each row of each column.

  The digital data stored in the image memory 39 is input to a personal computer as the image processing unit 23 via the PC interface (image board) 40. A display monitor 26 is connected to the personal computer, and the fundus oculi image Ef ′ is displayed in accordance with the operation of the operation unit 25.

  The composite synchronization signal generation circuit 33 generates a composite synchronization signal SYNC "for constructing a frame image based on the number of horizontal synchronization signals SYNC 'from the column counter 31 and the pixel clock signal PL from the row counter 35 as a PC interface. Output to 40.

  As a result, as shown in FIG. 2, the fundus oculi Ef is reciprocally scanned in the vertical direction (column direction) while being scanned in the horizontal direction (row direction), and one fundus image Ef ′ is taken into the storage unit 24. It will be.

  As shown in FIG. 2, when the environmental temperature is constant, the period of the vertical synchronization signal SYNC is constant, so that the image capture start corresponding to the shake angle position in the forward direction of the resonant mirror 10a shown in FIG. The timing signal PL ′ and the image capturing start timing signal PL ″ corresponding to the shake angle position in the backward movement direction of the resonant mirror 10a do not vary temporally.

  For this reason, the image capturing end position Qf by scanning in the forward direction and the image capturing start position Qs by scanning in the backward direction are aligned (the image capturing start position Q ′s by scanning in the forward direction and the backward direction). The image capturing end position Q′f by scanning is aligned).

  However, when the environmental temperature fluctuates, the period of the vertical synchronization signal SYNC is changed, so that the image capture start timing corresponding to the forward swing angle position of the resonant mirror 10a and the backward swing angle position of the resonant mirror 10a are changed. The corresponding image capture start timing changes with time, and as shown in FIG. 8, the image capture end position Qf by scanning in the forward direction and the image capture start position Qs by scanning in the backward direction are not aligned.

  As a result, when the fundus image Ef ′ as a frame image is constructed by combining the fundus image obtained by scanning in the forward direction and the fundus image obtained by scanning in the backward direction, the image obtained by scanning in the forward direction and the backward direction As shown in FIG. 9, there is a discontinuous frame image.

  In this embodiment, as shown in FIG. 1, the image capture end position Qf by scanning in the forward direction and the scanning in the backward direction are scanned at the position Q1 ″ conjugate with the fundus oculi Ef of the optical path of the fundus scanning optical system 1. A mask 41 for aligning the image capturing start position Qs and a mask 42 for adjusting the generation interval of the pixel clock PL are provided.

(Description of mask 41)
As shown in FIG. 10, the mask 41 has a square-shaped opening 41a, and comb teeth 41b are formed at equal intervals in the vertical direction on the periphery of the opening 41a. The mask portion 41a is black, and when the image obtained by scanning in the forward movement direction and the image obtained by scanning in the backward movement direction are combined, as shown in FIG. 11, a black comb tooth image 41b ′ in which the comb tooth portion 41b is displaced is shown. Is obtained.

FIG. 11 shows a comb-tooth image 41b ′ obtained by scanning Ai and Ai + 1 in the forward movement direction and a comb-tooth image Bi obtained by scanning Bi in the backward movement direction. A state where the comb image 41b ′ acquired by scanning in the forward direction and the image acquired by scanning in the backward direction is shifted is shown.
Reference numeral 41b ″ denotes a contour image that forms the contour of the peripheral portion in the vertical direction of the square opening 41a.

  The fundus image constructing unit 4 uses the comb image 41b ′ to capture the image capturing start timing corresponding to the forward swing angle position of the resonant mirror 10a and the backward swing angle position of the resonant mirror 10a. Adjust the start timing.

  The fundus image constructing unit 4 may obtain a plurality of fundus images Ef ′ including the comb image 41b ′ in advance before constructing the fundus image Ef, and may adjust the image capturing start timing. 41b ′ may be used to calculate the position of the comb teeth that maximizes the correlation coefficient, and to determine the image capture start timing.

The fundus image construction unit 4 may be configured to remove the comb image 41b ′ by trimming the fundus image Ef ′ including the comb image 41b ′ as a mask image.
In this embodiment, in FIG. 7, the pixel clock PL is depicted as if the pixel clock PL is being output from the pixel clock generation circuit 32 after a predetermined time from the vertical synchronization signal SYNC. For the sake of convenience, the pixel clock PL is drawn as a timing signal input to the image memory 39, and the pixel clock PL is output from the pixel clock generation circuit 32 at regular intervals using the vertical synchronization signal SYNC as a trigger. This means that image information is written to the image memory 39 from the time when a predetermined number is counted, and that the writing start timing of image information in the backward direction to the image memory 39 is adjusted with a mask.

(Description of mask 42)
As shown in FIGS. 10 and 12, the mask 42 has a square reflecting mirror surface 42a. In the case where there is no need to adjust the image capturing start timing corresponding to the shake angle position in the forward direction of the resonant mirror 10a and the image capture start timing corresponding to the shake angle position in the backward direction of the resonant mirror 10a, It is not necessary to form the comb teeth 41b on the mask 41.

  In the mask 42, a plurality of black line portions 42b extending in a direction crossing the reflecting mirror surface 42a are formed at equal intervals. As shown in FIG. 12, scanning by the resonant mirror 10a is performed in a direction perpendicular to the black line-shaped portion 42b.

  As shown in FIG. 1, the mask 42 is disposed at a position offset from the optical path of the fundus scanning optical system 1 and in a plane conjugate with the fundus oculi Ef. When scanning the mask 42, the galvanometer mirror 10b is offset by a predetermined angle with respect to the reference set angle when scanning the fundus oculi Ef. Appropriate means can be used for the offset of the galvanometer mirror 10b.

  If the generation intervals of the pixel clocks PL are equal, the angular velocity of the resonant mirror 10a decreases near the maximum deflection angle of the resonant mirror 10a, so that the speed crossing the black line portion 42b decreases, and the black line portion The number of dots acquired when crossing 42b increases.

  On the other hand, since the angular velocity of the resonant mirror 10a increases at an intermediate portion between the vicinity of the maximum deflection angle of the resonant mirror 10a and the vicinity of the maximum deflection angle, the number of dots acquired when crossing the black line portion 42b is increased. Relatively less. Further, the angular velocity of the resonant mirror 10a can be regarded as linear at an intermediate portion between the vicinity of the maximum deflection angle of the resonant mirror 10a and the vicinity of the maximum deflection angle.

  Therefore, when an image of the black line portion 42b is constructed with the generation intervals of the pixel clock PL being equal, as shown in FIG. 13, the black line extending in the vertical direction (longitudinal direction) in the vicinity of the maximum deflection angle of the resonant mirror 10a. In the middle portion between the maximum deflection angle of the resonant mirror 10a and the maximum deflection angle of the resonant mirror 10a, a black line-shaped image 42b 'contracted in the vertical direction (longitudinal direction) is obtained. It is done.

  Therefore, the fundus image construction unit 4 analyzes the black line-shaped image 42b ′ shown in FIG. 13, and the generation interval TH of the pixel clock PL is intermediate in the vicinity of the maximum deflection angle of the resonant mirror 10a as shown in FIG. Adjust so that it is larger than the occurrence interval TH of the part.

  FIG. 15 shows the relationship between the system clock signal, the pixel clock signal PL, the output data of the analog-to-digital converter (ADC) 36, and the write timing to the image memory 39. For a predetermined number of system clock signals, FIG. The number of dots (number of pixels) written in the image memory 39 decreases near the maximum deflection angle of the resonant mirror 10a, whereas, in the middle portion between the maximum deflection angle and the maximum deflection angle of the resonant mirror 10a. Since the number of dots (number of pixels) written in the image memory 39 is relatively large with respect to a predetermined number of system clock signals, as shown in FIG. 14, the maximum shake from the vicinity of the maximum shake angle of the resonant mirror 10a. A black line-shaped image 42b ′ having the same width is acquired between the corners.

  The adjustment of the image capturing interval by the mask 42 is performed, for example, at the time of factory shipment or when the fundus imaging apparatus is repaired. After the image capturing interval is adjusted, the galvano mirror 10b is set to a reference angular position for performing fundus scanning. .

DESCRIPTION OF SYMBOLS 1 ... Fundus scanning optical system 3 ... Image receiving optical system 4 ... Fundus image construction part 10 ... Scanning mirror (scanner)
22 ... Image receiver 30 ... Mirror drive circuit 42 ... Mask 42a ... Reflective mirror surface 42b ... Black line E ... Eye Ef ... Fundus SP ... Irradiation spot light SYNC ... Vertical synchronization signal SYNC '... Horizontal synchronization signal

Claims (3)

A fundus scanning optical system that scans the fundus while irradiating the fundus of the eye to be examined, an image receiving optical system that receives the irradiation spot light and outputs an image receiving signal, and an image receiving signal from the image receiving optical system. The fundus scanning optical system includes a scanning mirror that scans the fundus in the vertical direction and the horizontal direction, and the scanning mirror is moved forward by a mirror driving circuit. A mask that adjusts the generation interval of a pixel clock that is reciprocally oscillated between a direction and a backward movement direction and that is offset from the optical path of the fundus scanning optical system and that captures an image in a plane conjugate with the fundus provided, the fundus image constructing unit, scanning the fundus imaging apparatus characterized by adjusting the sampling intervals of the image with respect to deflection angle of the scanning mirror with an image of the mask. The fundus image constructing unit, an image in advance the mask before the fundus image by the backward direction of scanning of the scanning mirror and the eye fundus image by the forward direction of scan of the scanning mirror to construct a frame image synthesized 2. The scanning fundus imaging apparatus according to claim 1, wherein a plurality of fundus images including the image are acquired and an interval for capturing the images is adjusted. From the fundus scanning optical system that scans the fundus while irradiating the fundus of the subject's eye with the irradiation spot light, the image receiving optical system that receives the reflected spot light from the irradiation spot light and outputs an image receiving signal, and the image receiving optical system A fundus imaging method for use in a scanning fundus imaging apparatus having a fundus image construction unit for constructing a fundus image using the received image signal,
The fundus scanning optical system includes a scanning mirror that is reciprocally oscillated to scan the fundus, and is provided with a mask that adjusts the generation interval of a pixel clock for capturing an image at an optical path offset position of the fundus scanning optical system. fundus imaging method characterized that you adjust the sampling intervals of the image with respect to deflection angle of the scanning mirror with the image of the mask.