JP5590942B2 - Imaging apparatus, optical interference imaging system, program, and adjustment method of imaging apparatus - Google Patents

Description

  The present invention relates to an imaging apparatus capable of adjusting members inside the apparatus, an optical coherence tomography system, a program, and an adjustment method for the imaging apparatus.

  In recent years, an imaging apparatus using an optical coherence tomography applying a technology of a low coherence interferometer or a white interferometer has been put into practical use. This method and apparatus, which is also called optical coherence tomography (hereinafter referred to as OCT), is used for the purpose of obtaining a tomographic image of the fundus retina in the medical field, particularly in the ophthalmic region. According to this, the light from the light source is divided to create the measurement light and the reference light, and the measurement light is irradiated to the imaging target. The return light and the reference light of the measurement light irradiated on the eye to be examined are combined by a beam splitter, become interference light, enter the diffraction grating, and are dispersed, and converted into an electrical signal by the sensor. A tomographic image to be imaged can be obtained based on the interference light signal.

  In this OCT imaging apparatus, the positional relationship between the light beam of the interference light, the diffraction grating, and the sensor described above greatly affects the image quality of the tomographic image, so that it needs to be precisely aligned. As a technique for this adjustment, Patent Document 1 discloses a technique for aligning interference light with respect to a line sensor by moving a mirror and a diffraction grating by a piezoelectric element. Patent Document 2 discloses a technique for adjusting the position of the fiber end with respect to the diffraction grating based on the light irradiation state on the sensor.

Special table 2009-523564 JP 2008-203246 A

  However, it is not considered in any of these patent documents that the user confirms whether the adjustment is correct. Although adjustments appear in the image as good image quality, the image quality also changes depending on other factors, and the noise and brightness information in the formed tomographic image confirms whether the adjustment has been made properly. It was difficult to do.

The present invention has been made to solve such a problem, and a light source that emits low-coherence light , the low-coherence light is divided into a plurality of measurement lights and a plurality of reference lights, and the plurality of the plurality of light-transmitting objects that pass through an imaging target Each of the measurement light and interference light generating means for generating interference light with the reference light via the reference object corresponding to each measurement light, and receiving the generated plurality of interference lights , respectively Imaging means for converting into a corresponding electrical signal, image forming means for forming the image to be photographed based on the respective electrical signals obtained by the imaging means receiving the plurality of interference lights, and the imaging means side by side of the adjustment means the light receiving surface and the imaging means to adjust the relative positions of the light beams of the plurality of interference light received, each of the light receiving state of the plurality of interference light before Symbol imaging means for receiving It characterized by having a display control means for controlling shown.

  Each spectrum that is an original signal for forming in the OCT imaging apparatus is displayed, and the relative position between the light receiving surface of the imaging unit and the incident light can be adjusted, thereby reaching the light receiving surface of the imaging unit and the imaging unit. It is possible to accurately check whether the alignment of the light beam is properly performed.

It is a block diagram of the OCT imaging apparatus by this invention. It is a figure which shows the fundus image and tomographic image obtained by the OCT imaging apparatus. It is a figure which shows the example of a display which shows the light reception state of the line sensor. It is a figure which shows the positional relationship of a line sensor and a spectrum. It is a figure which shows the example of a display screen for adjustment. It is a figure which shows the example of a display screen for another adjustment. It is a figure which shows the example of a display screen for another adjustment. It is a flowchart which shows the flow of the process which adjusts a spectrometer. It is a flowchart which shows the flow of the automatic adjustment process of a spectrometer. It is a figure which shows the spectrum displayed on the light reception state of a line sensor, and a display screen. It is a figure which shows the spectrum displayed on the light reception state of another line sensor, and a display screen.

  Embodiments of the present invention will be specifically described below with reference to the drawings as appropriate.

  FIG. 1 is a block diagram showing a basic configuration of an OCT imaging apparatus (hereinafter referred to as an OCT apparatus) according to the present invention. As shown in FIG. 1, the OCT apparatus 100 constitutes a Michelson interferometer as a whole, and is a spectral domain OCT (hereinafter referred to as SD-OCT) or optical coherence tomography apparatus.

  The outgoing light 104, which is low-coherence light emitted from the light source 101, is guided to the single mode fiber 110 and enters the optical coupler 156, and the optical coupler 156 outputs 3 of the first optical path, the second optical path, and the third optical path. The light is divided into outgoing lights 104-1 to 104-3 passing through one optical path. Further, each of the three outgoing lights 104-1 to 104-3 passes through the optical fiber forming the optical path, passes through the polarization controller 153-1, and is referenced by the optical couplers 131-1 to 131-3 which are interference light generation units. The light is divided into light 105-1 to 10-3 and measurement light 106-1 to 106-1. The three measurement beams 106-1 to 106-3 divided in this way are returned as return beams 108-1 to 108-3 reflected or scattered by respective measurement points of the retina 127 in the eye 107 to be imaged. . Then, the optical couplers 131-1 to 131-3 serving as interference light generation units are combined with the reference beams 105-1 to 105-3 that have passed through the reference beam path to become combined beams 142-1 to 142-1. The combined lights 142-1 to 142-3 interfere with each other according to the difference in optical path length between the measurement light and the reference light, and become interference light. The synthesized lights 142-1 to 142-3 pass through the polarization controller 153-3 and exit from the end of the optical fiber. The emitted light is dispersed for each wavelength by the transmission diffraction grating 141 that is a spectroscopic unit, and is incident on a line sensor 139 that is an imaging unit via a lens 143, and the line sensor 139 receives the light. The line sensor 139 that is an imaging unit receives light of each wavelength for each sensor element, converts the light intensity into an electrical signal, and uses the signal to generate a tomographic image of the eye 107 to be examined in an image forming unit (not shown). Composed. Here, the light intensity is the amount of light incident on the sensor per unit time.

  The line sensor 139 that is an imaging unit can adjust the relative positional relationship between the light receiving surface on which the combined lights 142-1 to 142-2 are received by the electric stage 210 that is the adjusting unit and the luminous flux of the combined light. Here, the luminous flux means a bundle of rays. The relative position between the light receiving surface and the light beam means the geometric positional relationship between the light receiving surface and the light beam, and means the incident angle of the light beam toward the line sensor 139 with respect to the light receiving surface and the incident position or range. This adjustment is realized by the electric stage 210 translating or rotating the line sensor 139. The electric stage 210 is controlled by a computer 125 that functions as a control unit. In the present embodiment, the electric stage 210 issues a control command for the electric stage 210 in response to an adjustment instruction input in an operation unit (not shown) of the computer 125, and the electric stage 210 responds accordingly. The position of the sensor will be changed. When the relative positional relationship of the imaging unit and other optical members is shifted due to vibration, heat, or the like, the position of the light beam received by the imaging unit via the diffraction grating 141 and the line sensor is shifted. Then, the amount of light that should be received by some pixels of the line sensor 139 cannot be received. As a result, the signal intensity obtained by the line sensor 139 is lowered, and thus the image quality of the obtained image is deteriorated. Therefore, it is necessary to adjust the positional relationship between the line sensor 139 and the light beam received by the line sensor 139 so that the light can be received appropriately. Thereby, the light reception state of the reference light or the composite light received by the line sensor 139 can be changed. In accordance with such adjustment, the display of the light receiving state displayed on the display unit (not shown) is switched by the display control of the computer 125. A display example of the light receiving state will be described later.

  Next, the reference light path of the reference light 105 will be described. Each of the three reference beams 105-1 to 105-3 divided by the optical couplers 131-1 to 131-3 passes through the polarization controller 153-2 and is emitted as substantially parallel light by the lens 135-1. Next, the reference beams 105-1 to 105-3 pass through the dispersion compensation glass 115, and are collected by the lens 135-2 on mirrors 114-1 to 114 which are examples of the reference object. Next, the directions of the reference beams 105-1 to 105-3 are changed by mirrors 114-1 to 114-3, which are examples of reference objects, and are directed to the optical couplers 131-1 to 131-3 again. Then, the reference beams 105-1 to 105-3 pass through the optical couplers 131-1 to 131-3 and are guided to the line sensor 139. The dispersion compensating glass 115 compensates for the reference light 105 with respect to dispersion when the measurement light 106 reciprocates between the eye 107 and the scanning optical system.

  Further, reference numerals 117-1 to 3 are electric stages, and the optical path length of the reference beam 105 can be changed by moving in the direction shown by the arrows. The electric stages 117-1 to 117-3 are controlled by the computer 125, and the optical path lengths of the reference beams 105-1 to 105-3 can be changed independently or simultaneously.

  Next, the measurement optical path of the measurement light 106 will be described. Each of the measurement beams 106-1 to 106-3 divided by the optical couplers 131-1 to 131-3 passes through the polarization controller 153-4, and is emitted as substantially parallel light by the lens 120-3. Is incident on the mirror of the XY scanner 119 constituting the. Here, for the sake of simplicity, the XY scanner 119 is described as a single mirror, but in reality, two mirrors, an X scan mirror and a Y scan mirror, are arranged close to each other, and an optical axis is placed on the retina 127. Raster scan in a direction perpendicular to Further, the lenses 120-1, 3 and the like are adjusted so that the respective centers of the measurement beams 106-1 to 106-3 substantially coincide with the rotation center of the mirror of the XY scanner 119. The lenses 120-1 and 120-2 are optical systems for the measurement light 106-1 to 106-3 to scan the retina 127, and have a role of scanning the retina 127 using the measurement light 106 near the cornea 126 as a fulcrum. The measuring beams 106-1 to 106-3 are each configured to form an image at an arbitrary position on the retina.

  Reference numeral 117-4 denotes an electric stage which can move in the direction shown by the arrow, and can adjust and control the position of the associated lens 120-2. By adjusting the position of the lens 120-2, each of the measurement beams 106-1 to 106-3 can be condensed and observed on a desired layer of the retina 127 of the eye 107 to be examined. When the measurement beams 106-1 to 106-3 enter the eye 107 to be examined, the reflected beams 108-1 to 108-3 are reflected and scattered from the retina 127, pass through the optical couplers 131-1 to 131-3, and are guided to the line sensor 139. The electric stage 117-4 is controlled by the computer 125. With the above configuration, three measurement beams can be scanned simultaneously.

  Next, the configuration of the detection system will be described. The return beams 108-1 to 108-3 and the reference beams 105-1 to 105-3 reflected and scattered by the retina 127 are combined by the optical couplers 131-1 to 131-3. Then, the combined synthesized light 142-1 to 142-3 enter the spectroscope, and a spectrum is obtained. A tomogram can be obtained by the computer 125 performing a tomogram reconstruction process on these spectra.

  The reconstruction process may be performed by a general OCT image generation process, and a tomographic image can be generated by performing fixed noise removal, wavelength wave number conversion, and Fourier transform. FIG. 2 illustrates an example of a region on the retina of the fundus and a tomographic image taken by the OCT apparatus described above. The fundus 501 includes a macular 502, an optic disc 503, a blood vessel 504, and the like. The three measuring beams 106-1 to 106-3 scan the first scanning range 505, the second scanning range 506, and the third scanning range 507 in correspondence with each other. Each region overlaps by about 20%, such as an overlap 508 between the first scan range and the second scan range, and an overlap 509 between the second scan range and the third scan range. The coordinate axes are set as shown in the figure. Scanning in the x direction is called Fast-Scan, y direction is called Slow-Scan, and the z direction is from the back of the paper to the front.

  Here, for example, 1024 lines are scanned in the x direction and 1024 lines are scanned in the y direction per one measuring beam. However, in the y direction, 512 lines are scanned with three measurement lights except for an overlapping portion. Finally, a rectangular area indicated by an alternate long and short dash line shown in FIG. 2A is an imaging range on the fundus. A tomographic image is acquired at.

  On the other hand, near-infrared light 190 emitted from the near-infrared light source 180 is applied to the fundus 127 through the half mirror 200, the illumination optical system 150, and the dichroic mirror 220 inserted in the measurement optical path. Near-infrared light reflected from the fundus returns again on the same optical path and forms an image on the two-dimensional area sensor 170 via the half mirror 200 and the imaging optical meter 160. The two-dimensional fundus image captured in this manner is input to the computer 125. This two-dimensional image is used for observing an OCT imaging region.

  Incidentally, reference numeral 230 in the measurement light path is a shutter, and the drive of the measurement light 106-1 to 106-3 can be opened or blocked by a driving device (not shown) under the control of the computer 125.

  Hereinafter, the relationship between the display screen and the light receiving state of the line sensor will be described with reference to FIGS. FIG. 3 is a diagram illustrating a display example of the spectrum of each reference light projected on the line sensor 139. As shown in the figure, three spectra 144-1 to 144-3 are projected on the sensor, and the signal read from the line sensor 139 is reconstructed for each of the areas indicated by SR 1 to SR 3 to form a tomographic image. Generated. Based on this tomographic image, display image data is generated by the computer 125 which is a display control unit and displayed on a display unit (not shown). FIG. 4 is a diagram showing the positional relationship between the light beam received by the line sensor 139 and the light receiving surface of the line sensor 139. In FIG. 4, the light receiving surface of the line sensor 139 is shown, and the spectrum of light incident on the light receiving surface in the direction from the front side to the back side of the paper is shown by diagonal lines.

  FIG. 3A is an example of display, and is an example in which the value of the electrical signal corresponding to the amount of light received by the line sensor 139 on the light receiving surface is displayed as it is. In FIG. 3A, the horizontal axis corresponds to the position of the line sensor and simultaneously corresponds to the wavelength, and the vertical axis corresponds to the signal intensity for each wavelength. Note that the frequency may be taken on the horizontal axis and the intensity for each frequency may be displayed.

  A light receiving state corresponding to the state shown in FIG. 3A is shown in FIG. In FIG. 4A, the spectrums 144-1 to 144-3 corresponding to each measurement light are appropriately incident on the light receiving surface of the line sensor 139. Therefore, the peak of the spectrum shown in FIG. 3 (a) is large and there is little variation between spectra. Thus, by displaying the shape of the spectrum, the light receiving state of the line sensor can be presented to the user in an easily understandable manner.

  FIG. 3B shows another display example, in which the positional relationship between the line sensor 139 and the reference light beam is shifted. In FIG. 3B, the spectrum 144-1 and the spectrum 144-2 are smaller than the spectrum 144-3. This is a phenomenon that occurs because the light received by the portions corresponding to the regions SR1 and SR2 of the line sensor 139 is weak. In such a case, it is considered that the light beam of the reference light and the light receiving surface of the line sensor 139 are relatively rotated. Or it is also considered that the optical component which guides the reference light corresponding to spectrum 144-1 and spectrum 144-2 has shifted.

  FIG. 4B shows a light receiving state corresponding to the state shown in FIG. In FIG. 4B, the line sensor 139 is inclined with respect to the light flux of each measurement light. In particular, the spectrum 144-1 is not properly incident on the line sensor 139. Correspondingly, the peak of the spectrum 144-1 is small in FIG. In this way, when the position of the light is shifted from the line sensor 139, the shape of the spectrum changes, and the light receiving state of the line sensor 139 can be visually presented to the user.

  The effects described above with respect to the display in FIGS. 3A and 3B are not limited to the multi-beam type OCT apparatus, but have the same effect on a single beam type OCT apparatus. It is. In the case of a multi-beam type device, since there are a plurality of spectra to be displayed, by displaying so that the shapes of the spectra can be compared with each other, the light receiving state is displayed in an easy-to-understand manner, and the line sensor and the light The relative position shift can be presented to the user. In the single beam type OCT apparatus, the light receiving state is determined by the shape of one spectrum. In contrast, in the multi beam type, a plurality of shapes can be compared. I can expect. In addition, in the OCT imaging apparatus using a plurality of measurement beams of multi-beams, it is necessary to appropriately align each combined light with respect to the line sensor so that the image quality does not differ for each measurement region by each measurement light. There is. Therefore, the necessity of adjusting the spectrum corresponding to each measurement light by the display illustrated in FIG. 3 is higher than that of a single beam, and the display illustrated in FIG. 3 is also significant from this point.

  FIG. 3C is a diagram showing another display example, and the size of each spectrum is smaller than that in FIG. This is because although the line sensor 139 and the light beam of the reference light are not relatively rotated, they have moved relatively in parallel, and the light received by each part of the line sensor 139 becomes weak overall. It is thought that it has been.

  A light receiving state corresponding to the state shown in FIG. 3C is shown in FIG. In FIG. 4C, it can be seen that the line sensor 139 is shifted in the direction perpendicular to the longitudinal direction with respect to the speed of light, and therefore the light receiving state of each spectrum is uniformly deteriorated.

  FIG. 3D shows another display example in which the peak size of each spectrum is displayed as a numerical value corresponding to each spectrum 144-1 to 144-3. The size of the peak is used as a feature amount indicating the light amount or light intensity of each reference light. Thus, by displaying the peak size as a numerical value, there is an advantage that it is possible to present not only the shape of the spectrum but also the amount to be adjusted as the numerical value of the peak to the user. When the spectrum is uniformly small as shown in FIG. 3 (c), it may be unclear whether there is a problem in the light receiving state by just looking at the shape of the spectrum, but numerical values are displayed. Thus, even in such a case, the abnormality of the light receiving state can be presented to the user in an easily understandable manner.

  [Modification] In the above-described embodiments, the light spectrum is displayed as an indication of the light reception state by the line sensor. However, the present invention is not limited to this, and the peak value or area of the spectrum may be displayed. . In addition, a display may be performed to indicate whether or not light of a threshold value or more is applied to each of the region SR1 to SR3 of the line sensor that receives reference light or interference light corresponding to each measurement light.

  In the above-described embodiment, an example in which light emitted from one light source is divided by an optical coupler as a multi-beam type optical coherence tomography apparatus having a plurality of measurement lights is not limited to this. You may have. In this case, a plurality of light sources having relatively low light intensity can be used without using a single light source having high light intensity. Moreover, you may provide a line sensor independently for every measurement light. In this case, it is necessary to adjust each line sensor independently, but the positional relationship between the light flux received by the sensor and the sensor can be adjusted more precisely.

  Furthermore, although the example which adjusts the position of a line sensor was shown in the above-mentioned Example, not only this but the light beam which a line sensor receives, and the positional relationship of a line sensor should just be adjusted. For example, adjusting the position of the diffraction grating, adjusting the position of the fiber end of the optical fiber and the direction of the light emitted from the fiber end, or adjusting the position of the lens between the fiber end and the spectroscopic unit Alternatively, the position of the lens between the diffraction grating and the line sensor may be adjusted. If the line sensor can be precisely positioned in advance, the light receiving state can be adjusted by adjusting the position of the optical member.

  In the present embodiment, an A-scan image, an A-scan profile, a B-scan image, and the like are displayed together with the spectrum display shown in the display example of the first embodiment. In addition, a display screen that can be adjusted and confirmed by scanning an icon on the display screen is provided. The computer 125 acquires the output of the line sensor 139 and creates spectrum information, an A scan image, and a B scan image used for the display screen. Setting information such as icon images and display arrangement is stored in the computer 125 in advance. The computer 125 executes processing for generating display screen image data based on the acquired information and setting information and controlling the display. On the display screen, the user can click a button or other icon using a mouse or a keyboard (not shown) connected to the computer 125. The operation information is acquired by the computer 125, and the electric stage 210 is controlled according to the operation information. Based on the newly obtained output from the line sensor 139, the computer 125 generates image data of a new display screen and performs display control to display on the display unit. As a result, the display screen is switched.

  FIG. 5 is an example of a display screen for adjustment. In the spectrum display area 600, three spectra as illustrated in FIG. 3 in the above-described embodiment are displayed. The display of the spectrum is sequentially updated by the computer 125 continuously processing the output of the line sensor 139 and performing display control.

  Reference numerals 603-1 to 603 denote tomographic signal display areas on which signals obtained by reconstructing the three spectra 1444-1 to 144-3 are displayed. In this embodiment, the profile is called an A-scan image or A-scan line profile. On the other hand, the tomographic image display area 605 is an area for displaying a plurality of A scans obtained by driving the X scan mirror as a two-dimensional image by a known interpolation process. In the following description, the tomographic image composed of the plurality of A scans is referred to as a B scan image. In the display example shown in FIG. 5, since the reference light is displayed, the A-scan image or the B-scan image is not displayed in the tomographic signal display areas 603-1 to 603-3 and the tomographic image display area 605.

  The area selection buttons 606-1 to 606-3 are icons for selecting which of the tomographic images by the three measurement lights are displayed. When the operator of the apparatus presses the switch indicated as area A, a tomographic image corresponding to the cross section A-A ′ shown in FIG. 2A is displayed in the tomographic image display area 605. By depressing the display of the region B, the cross section of B-B ′ is displayed, and by depressing the display of the region C, the cross section of C-C ′ is displayed. In this embodiment, since the spectrum display is the reference light, the display of the spectrum display area 600 or the tomographic signal display areas 603-1 to 603-3 is not changed.

  Next, a slider 604-1 and a slider 604-2 in the figure are sliders for adjusting the position of the line sensor 139 with respect to the spectrum by driving the electric stage 210. By operating this, the height and rotation of each sensor with respect to the spectrum can be adjusted. Here, the height refers to a displacement or movement amount in a direction orthogonal to the longitudinal direction of the line sensor, and rotation refers to a plane including the light receiving surface passing through the center point with respect to the longitudinal direction of the line sensor 139. Refers to rotation around an orthogonal axis. The center of rotation is not limited to the midpoint with respect to the longitudinal direction of the line sensor 139. Moreover, you may enable it to translate or rotate out of the plane including a light-receiving surface. For example, it may be movable in three axial directions using a motor and a feed screw. Since the display of the spectrum display region 600 is switched according to the operation of the slider, the user can adjust the position of the line sensor by the operation on the screen and can check the adjustment result on the display screen. .

  The light source buttons 607-1 and 607-2 turn on or off the power of the light source 101, whereby the emission of low coherence light from the light source 101 is stopped, and the spectrum is not displayed in the spectrum display region 600. The shutter buttons 608-1 and 608-2 can be operated by an operator to drive the shutter 230 to block or release the optical path of the measuring beams 106-1 to 106-3. When the optical path is opened by the shutter 230, when the eye to be examined is arranged at the tip of the objective lens, interference light including tomographic information of the retina is obtained, and the spectrum of the interference light is displayed in the spectrum display region 600. Become.

  In the above-described display example, the spectroscope is adjusted using only the reference light in a state where the measurement light is blocked by operating the shutter 230. However, this is not essential in the present invention, and a stable standard such as a model eye is used. Adjustment may be performed using a typical subject. In this case, the adjustment is performed with the shutter button 608-1 being pressed by the operator and the shutter 230 being opened. In this embodiment, a model eye on which a multilayer film is formed as a subject is set in the OCT imaging apparatus, and the adjustment screen when the shutter is opened by the shutter button 608-1 is as illustrated in FIG. That is, a tomographic image of the model eye is displayed in the tomographic image display area 605, and a tomographic signal (A scan profile) generated from each spectrum is displayed in the tomographic signal display areas 603-1 to 603-3.

  With such a display, for example, by referring to both the light receiving state of each measurement light and the A scan profile, the magnitude of the signal component can be confirmed for a certain A scan profile, and the user can determine whether adjustment is necessary based on the magnitude. Information can be presented.

  Further, by referring to the B scan image together with the A scan profile, for example, in the region where the noise is high in the B scan image, it is confirmed whether there is any abnormality in the spectrum of the interference light, and the cause is specified. Information can be presented. It is also possible to display the reference light by pressing the shutter button 608-2 to block the optical path in a state where the A scan image and the B scan image are displayed.

  The display of the tomographic image display area 605 can be switched by area selection buttons 606-1 to 606-3 provided at the top thereof. FIG. 6 shows a state where the center area A is selected, and a B-scan image of the measurement light in the area A is displayed in the tomographic image display area 605. When the selected area is switched, the B-scan image at the selected position is displayed in the tomographic image display area 605. At the same time, the spectrum of the interference light corresponding to the selected region is displayed in the spectrum display region 600, and the A scan profile is displayed in the tomographic signal display regions 603-1 to 603-3. In this way, the display is switched according to the selection of the region selection buttons 606-1 to 606-3. It should be noted that it is determined in advance according to the selection of the region which interference light based on the measurement light irradiated to which position of the imaging target is to be displayed. For example, the interference light at the center position or the interference light at the end may be used for each measurement light. Further, the average of interference light spectra corresponding to a plurality of A scan positions may be taken and displayed.

  As described above, the display of the spectrum, the A-scan image, and the B-scan image is switched according to the selection of the region, whereby the intensity of the signal in the image can be confirmed for each region.

  In the optical interference imaging apparatus according to the present embodiment, in addition to the mode in which the user manually adjusts the spectrometer, a mode in which the spectrometer is automatically adjusted can be executed. An example of a display screen whose display is controlled by the computer 125 is shown in FIG. On this display screen, a button 602 for instructing execution of automatic adjustment is displayed as an icon, and automatic adjustment is executed when the user presses a button on the screen using an operation unit (not shown).

  Next, a method for adjusting a spectroscope performed in the above-described OCT imaging apparatus prior to imaging of the eye to be examined will be described with reference to FIG. The processing described below is realized by a control program executed on the computer 125 shown in FIG. 1 controlling the operation of each unit.

  [Step S100] The computer 125 displays a spectrometer adjustment screen on the monitor 130. Since the display screen is the same as that of the second embodiment described above, a description thereof will be omitted, except that an automatic adjustment button 602 is arranged.

  [Step S200] The computer 125 detects whether or not the automatic adjustment button 602 has been pressed by the operator. If the button has not been pressed, the process proceeds to the manual mode in step S300, and if not, the process proceeds to the automatic mode in step S400. To do.

  [Step S300] The computer 125 monitors the pressing of each operation button shown in FIG. 7, and shifts to a manual mode in which adjustment is performed by an operator's operation. In the manual mode, the position of the line sensor 139 is manually adjusted by an operator's operation. In this mode, the height of each spectrum displayed in the spectrum display region 600 is adjusted or within a predetermined range while adjusting the height of the line sensor 139 with the slider 604-1 and the rotation with the slider 604-2. And adjust it to be as high as possible.

  First, in this embodiment, it is assumed that the adjustment is performed with the shutter 230 blocking the measuring beams 106-1 to 106-3. That is, it is assumed that the shutter button 608-2 is pressed by the operator, the shutter 230 blocks the measurement light, and the spectrum of only the reference light 105-1 to 105-1 enters the line sensor 139. Therefore, a tomographic image cannot be generated even if the detected signal is reconstructed, but the interference component depending on the subject itself is an unnecessary signal for viewing the balance of each spectrum, which is preferable.

  In the present embodiment, since the measurement light is blocked as described above, nothing is displayed in the tomographic signal display areas 603-1 to 603-3 and the tomographic image display area 605. Next, the position adjustment of the line sensor in the manual mode will be specifically described.

  For example, if the shape of the spectrum displayed in the spectrum display region 600 immediately after the start of adjustment is in the state shown in FIG. 3B, the computer 125 drives the electric stage 210 when the operator operates the slider 604-2. Then, the line sensor 139 is rotated. Further, by operating the slider 604-1, the operator observes the shapes of the spectra 144-1-3 displayed in the spectrum display area 600, and the height of the line sensor 139 is adjusted so that the heights are uniform and the highest. Adjust the position.

  When the positional relationship between the line sensor and the spectrum is as shown in FIG. 4C, the spectrum detected by the line sensor corresponds to the state of FIG. When the slider 604-2 is operated here, the computer 125 rotationally drives the line sensor 139, and the state shown in FIG. Next, when the slider 604-1 is operated, the computer 125 moves the line sensor 139 in parallel, and finally the state shown in FIG. As a result, the line sensor is properly aligned with each spectrum.

  Further, as described above, when the operator aligns the line sensor, the area or peak value of each spectrum that is sequentially input by the computer 125 is calculated, and the calculated numerical value is in the vicinity of the spectrum in the spectrum display region 600. It may be displayed. This is preferable because the height and balance of each spectrum can be easily confirmed.

  FIG. 3D is an example of a display form, and the peak values calculated by the computer 125 for each spectrum are displayed together with arrows. In this example, the peak value of the spectrum is displayed. Of course, other numerical values such as an area may be used, and the display position may be anywhere on the display screen shown in FIG.

  [Step S400] When the automatic adjustment button 602 is pressed by the operator in step S200, the computer 125 shifts to the automatic mode. In this mode, the adjustment described in step S300 is automatically performed.

  The flow of the automatic mode process will be described below with reference to the flowchart shown in FIG.

  [Step S410] The computer 125 turns on the power of the light source 101, and further operates the shutter 230 to block the measuring beams 106-1 to 106-3. As a result, only the spectra of the reference beams 105-1 to 105-3 are incident on the line sensor 139.

  [Step S420] The computer 125 moves the position of the line sensor 139 to a state where none of the three spectra is incident. FIG. 10A shows the positional relationship between the line sensor and the spectrum at this time and the intensity of the spectrum detected by the line sensor, and no spectrum is detected at this step. At this time, it is preferable that the line sensor 139 is rotated by a predetermined angle in advance because the rotation direction can be basically adjusted based on one direction in the subsequent steps. This angle may be a value that sufficiently exceeds the angle obtained from the estimated relative deviation between the line sensor and the spectrum in advance due to the assembly error of the apparatus.

  [Step S430] The computer 125 sequentially inputs the spectrum detection result from the line sensor 139 while translating the line sensor 139 in the direction indicated by the upward arrow in FIG. Here, the height of the center spectrum 144-2 is monitored, and the movement is stopped at a position where it becomes the maximum. The state at this time is shown in FIG.

  [Step S440] The computer 125 checks whether or not the difference in spectral height detected by the line sensor 139 is within an allowable range, and if it is within the allowable range, proceeds to step S460, otherwise proceeds to step S450. This allowable range may be determined based on the difference in image quality caused by the difference between spectra. That is, the height of the spectrum affects the sensitivity of extracting the structure of the subject. If the height of the spectrum is low, the sensitivity decreases as a whole, and the tomographic image obtained by reconstruction becomes dark. Accordingly, if the degree of difference between the scanning ranges 505 to 507 shown in FIG. 2A is determined by subjective evaluation or the like, the allowable range can be determined with respect to the height of the spectrum.

  [Step S450] The computer 125 sequentially inputs the spectrum detection results from the line sensor 139 while rotating the line sensor 139 in the direction indicated by the arrow in FIG. In this step, all the heights of the three spectra 144-1 to 144-3 are monitored, and the rotation is stopped at an angle at which the three heights are substantially the same. The state at this time is shown in FIG.

  [Step S460] The computer 125 checks whether or not the heights of the three spectra and the difference between them are within the specified range. If they are within the specified range, the adjustment is terminated. If not, the process returns to Step SS430. . When the process moves to step S430, the line sensor 139 is moved as shown in FIG. 10C, and the same process is repeated again.

  Here, the specified range related to the height of the spectrum may be determined based on the image quality in each scanning range and the difference as described in step S440.

  As described above, according to the present invention, it is possible to appropriately adjust the position of the sensor and the combined light in the spectroscopic adjustment of the tomographic imaging apparatus having a plurality of measurement lights. In the present embodiment, the height is used as an index representing the characteristics of the spectrum detected by the line sensor 139. However, the present invention is not limited to this, and for example, the spectrum area may be used. Good.

  [Modification] In addition to the adjustment using the reference light, the spectroscope may be adjusted using a spectrum including an interference signal. The processing flow is basically the same as in the first embodiment. However, since the spectrum detected by the line sensor 139 includes an interference signal, the height of the spectrum including the interference signal is adjusted when evaluating the height of the spectrum in steps S440 and S460.

  Alternatively, when performing the initial setting in step S410, first, the three spectra 144-1 to 144-3 are acquired with the shutter 230 closed and stored in the memory inside the computer 125. Next, it is possible to subtract from the spectrum acquired with the shutter 230 released to obtain only the interference signal and use the amplitude of this signal as an index.

  In this way, the spectroscope can be adjusted so as to maintain the same level of image quality for a standard subject.

  In the embodiment described above, the line sensor 139 includes only one row of detection elements. However, the present invention can be applied to a two-dimensional sensor or a line sensor having a plurality of rows. FIG. 11 illustrates a spectrum when such a sensor is used. In the line sensor 139, two rows of detection elements 139-1 and 139-2 are arranged, and these are input to the computer 125, respectively.

  At this time, there are two spectra to be detected, the spectrum by the detection element array 139-1 is shown by a broken line, and the spectrum by 139-2 is shown by a solid line. In such a case, when adjusting the position of the line sensor 139, the values of these two spectra are adjusted to be the same or within a predetermined range. Therefore, in the above-described embodiment, these two types of spectra are displayed so as to be distinguishable in the spectrum display region 600 as illustrated in FIG. At the same time, adjustment is performed so that these indices such as height and area are not less than a certain value and the mutual variation is within a predetermined range.

  [Other Embodiments] In the above-described embodiments, the embodiment in which the circuit corresponding to each functional block in the optical coherence tomography system or the image processing apparatus realizes the present invention has been described. It is not limited to this. For example, the processing performed in the image processing apparatus can be realized by distributing a plurality of devices as a system, or the processing combined as one functional block can be realized by distributing the processing by a plurality of circuits or devices. Good. Note that the present invention may be realized by an optical coherence tomography apparatus by incorporating the functions of the image processing apparatus and the display device in the above-described embodiment into the optical coherence tomography apparatus.

  The present invention also provides a system or apparatus with a recording medium that records software program codes for realizing the functions of the above-described embodiments, and the CPU stores the program code stored in the recording medium by the arithmetic unit of the system or apparatus. It is realized by executing. Also, by executing the program code read by the computer, an operating system (OS) running on the computer performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing. This is also included. A plurality of CPUs may be included in the computer. In this case, the present invention may be realized by distributing the CPUs.

  In this case, the program code read from the recording medium itself realizes the functions of the above-described embodiments, and the recording medium recording the program or the program code constitutes the present invention.

  Further, the program code read from the recording medium is written in a memory in the function expansion card or function expansion unit attached to the computer, and the arithmetic unit in the expansion card or expansion unit performs part or all of the actual processing. This includes the case where the functions of the embodiment are realized. In this case, the present invention is realized by a circuit implemented by hardware and a function realized by cooperation of software and hardware.

  Note that the description in the present embodiment described above is an example of a suitable fundus tomography apparatus according to the present invention, and the present invention is not limited to this.

DESCRIPTION OF SYMBOLS 100 OCT imaging apparatus 125 Computer 139 Line sensor 141 Diffraction grating 210 Electric stage 600 Spectrum display area 602 Automatic adjustment button 604-1 Line sensor height adjustment slider 604-2 Line sensor rotation adjustment slider

Claims (7)

A light source that emits low coherence light;
The low-coherence light is divided into a plurality of measurement lights and a plurality of reference lights, and interference between each of the plurality of measurement lights passing through the object to be photographed and the reference light passing through a reference object corresponding to each measurement light Interference light generating means for generating light respectively;
Imaging means for receiving the plurality of generated interference lights and converting them into corresponding electrical signals;
Image forming means for forming an image of the object to be photographed based on respective electrical signals obtained by the imaging means receiving the plurality of interference lights; and
And adjusting means for said imaging means and the light receiving surface of the imaging means to adjust the relative positions of the light beams of the plurality of interference light received,
Photographing apparatus before Symbol imaging means and having a display control means for displaying side by side each of the light receiving states of the plurality of interference light received. The imaging apparatus according to claim 1, wherein the display control unit displays spectrum intensities of the plurality of interference lights received by the imaging unit.   The imaging apparatus according to claim 2, wherein the display control unit displays a peak value of the spectrum. The imaging apparatus according to claim 1, wherein the display control unit displays a difference between values indicating the light amounts of the plurality of interference lights. The photographing device according to claim 4 in which the difference between the value indicating the amount of pre Shiruso respectively is characterized by further comprising a control means for controlling the adjusting means so that the predetermined range.   The imaging apparatus according to claim 5, wherein the adjustment by the adjustment unit is a rotational movement and a parallel movement of the imaging unit. The low-coherence light emitted from the light source is divided into a plurality of measurement lights and a plurality of reference lights, and each of the plurality of measurement lights passing through the imaging target and the reference via the reference object corresponding to each measurement light Generating interference light with each light,
The imaging unit receives the plurality of generated interference lights and converts them into corresponding electrical signals;
Forming an image of the subject to be photographed based on each electrical signal obtained by the imaging unit receiving the plurality of interference lights; and
Adjusting the relative position between the light receiving surface of the imaging unit and the light beams of the plurality of interference lights received by the imaging unit;
Adjusting method of the imaging device before Symbol imaging unit and having a step of arranging and displaying a respective light receiving state of the plurality of interference light received.

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