JP2011024719A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the color deviation in an image when forming and displaying the image in an image forming apparatus with a scanning optical system. <P>SOLUTION: The image forming apparatus includes: the scanning optical system (40) for scanning and illuminating an object area (100) with light from a light source (1); a dispersing unit (32) for dispersing the light from the object area (100); a photodetector (33) for receiving the light dispersed by the dispersing unit and generating signals corresponding to the intensity of the detected light at a plurality of sampling times; a memory (34) for reading the signals; and a control unit (15) for reading the signals from the memory and displaying them at a display device (35). The interval (t<SB>m+1</SB>(λ)-t<SB>m</SB>(λ)) of the sampling time of the photodetector changes in accordance with the wavelength of the dispersed light. The control unit changes the elapsed time (Tp) from the read of the signals by the memory to the display of the signals at the display device by the control unit by the wavelength of the dispersed light. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus. The image forming apparatus is used together with, for example, an endoscope or a microscope.

  An endoscope optical system that scans an object by deflecting illumination light without mechanical driving by providing an electro-optic element at the tip is known (Patent Document 1).

Special Table 2002-523162

  However, in the above prior art method, since the electro-optic crystal of the electro-optic element has a large refractive index wavelength dispersion, the position of spot illumination on the object is shifted according to the wavelength when a light source in the visible region is used. As described above, in an image forming apparatus using a scanning optical system having a large lateral chromatic aberration such as an electro-optical element, when a color image is formed using return light from an object, there is a problem that color misregistration occurs in the image. there were.

  An object of the present invention is to prevent color misregistration of an image when an image is formed and displayed in an image forming apparatus having a scanning optical system.

  An image forming apparatus according to an aspect of the present invention includes a light source, a scanning optical system that scans and illuminates a target region with light from the light source, a spectroscopic unit that splits light from the target region, and the spectroscopic unit A light detector that receives the light separated by the light and generates a signal corresponding to the intensity of the detected light at a plurality of sampling times, a memory that reads the signal, a signal that is read from the memory, and the target area And a control unit that forms the image and displays the image on a display device. The sampling time interval of the photodetector varies according to the wavelength of the dispersed light. The control unit changes an elapsed time from when the memory reads the signal until the control unit displays the signal on the display device according to the wavelength of the dispersed light.

  According to the present invention, when an image is formed and displayed in an image forming apparatus having a scanning optical system, color misregistration of the image can be prevented.

1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment. It is a figure explaining the difference in the scanning position (spot position) by the wavelength of light. It is a figure which shows how the light ray bends in an electro-optic element. The case where the voltage applied to the voltage electrode is positive is shown. It is a figure which illustrates the dependence of the applied voltage V of the output angle (theta). It is a graph which shows an example of an applied voltage waveform (time dependence of an applied voltage). It is a graph which shows an example of time dependence of outgoing angle θ. The sampling time for each color is illustrated. A solid line indicates blue light and a dotted line indicates red light. It is a graph which shows the other example of an applied voltage waveform (time dependence of an applied voltage). It is a graph which shows the other example of the time dependence of the output angle (theta). The sampling time for each color is illustrated. A solid line indicates blue light and a dotted line indicates red light. It is a partial block diagram which shows the image forming apparatus which concerns on 2nd embodiment.

<First embodiment>
The image forming apparatus will be described with reference to FIG. The embodiment will be described assuming that the image forming apparatus is used together with an endoscope. However, this embodiment is applicable without being limited to this. For example, the image forming apparatus may be used with a microscope.

  The image forming apparatus includes an optical scanning device (in this case, an endoscope) 200 that scans a scanning target region 100 of an object with light and a signal processing unit 300. The optical scanning device 200 includes a light source 1, a light emitting unit 3 (light emitting unit), a fiber bundle 7, and a scanning unit 9 (scanning unit). The optical scanning device 200 includes a scanning optical system 40 that scans and illuminates the scanning target region 100 with light from the light source 1. In the present embodiment, the scanning optical system 40 includes the light emitting unit 3, the fiber bundle 7, the scanning unit 9, and the lens groups 5, 11, and 13, but is not limited thereto.

  The signal processing unit 300 includes a spectroscope (spectral unit, spectroscopic unit) 32, a light detector (photodetection unit) 33 for each color, a memory (storage medium) 34, a controller (control unit) 15, a monitor (display device) 35, and the like. Consists of The controller 15 includes a central processing unit (CPU), a memory, and the like, and functions as a control unit or a control unit that controls the light source 1, the galvano mirrors 3a and 3b of the light emitting unit 3, the scanning unit 9, and the like. Examples of the photodetector 33 include a photodiode, a CCD (charge coupled device), a photomultiplier tube, and the like. In FIG. 1, the fiber bundle 7 is described using a perspective view.

  The light source 1 emits red (R) light (wavelength λr), green (G) light (wavelength λg), and blue (B) light (wavelength λb) as light of the three primary colors. The light source 1 may emit three primary colors by including a white light source and an RGB filter. Alternatively, the light source 1 may be one that emits light of the three primary colors by including red (R), green (G), and blue (B) light emitting diodes or laser diodes. The light source 1 is not limited to the three primary colors, and may emit a desired number of light of a desired color. In the following, a case will be mainly described where light of a plurality of colors from the light source 1 is simultaneously emitted and applied to the scanning target region 100. However, the scanning target region 100 may be irradiated with light of each color in order at different times by a surface sequential method.

  The light emitting unit 3 emits light from the light source 1 toward one of the fibers on one end face (proximal end) of the fiber bundle 7. Accordingly, the light emitting unit 3 sequentially selects one optical fiber from the plurality of n optical fibers of the fiber bundle 7 and causes light to enter the selected optical fiber. The light reaches the scanning unit 9 through the selected optical fiber.

  In this embodiment, the light emission part 3 is comprised from the 1st and 2nd galvanometer mirrors 3a and 3b which perform a deflection | deviation operation | movement to a mutually perpendicular | vertical direction. The galvanometer mirrors 3a and 3b are controlled by the controller 15 via an actuator (such as a motor) not shown. The light emitting unit 3 performs two-dimensional scanning at the proximal end of the fiber bundle 7 using the two galvanometer mirrors 3a and 3b. The controller 15 may change the angle of the galvanometer mirrors 3a and 3b continuously (analogously). In this case, while the light passes through one fiber, one optical path through the fiber is selected. Note that the controller 15 may numerically (digitally) control the angles of the galvanometer mirrors 3a and 3b.

  The fiber bundle 7 is composed of a plurality of n optical fibers that are bundled. Each optical fiber transmits the incident light at the proximal end of the fiber bundle 7 and emits it from the other end face (distal end) of the fiber bundle 7. Note that n is, for example, several to thousands.

  A lens group 5 is appropriately provided between the light emitting unit 3 and the fiber bundle 7. The focal point of the lens group 5 is adjusted so that the light emitted from the light emitting unit 3 enters one optical fiber of the fiber bundle 7. A lens group 11 is also appropriately provided between the fiber bundle 7 and the scanning unit 9. The lens group 11 makes the light from the optical fiber substantially parallel and enters the scanning unit 9. The light from the scanning unit 9 is focused by the lens group 13 on a scanning target region (scanning target surface) 100 that is a target of scanning of the target object. The scanning range is expanded by the lens group 13 at a predetermined magnification. Each of the lens groups 5, 11, and 13 includes one or more lenses.

  The scanning unit 9 continuously and periodically scans the scanning target region 100 with the emitted light emitted from the distal end of the fiber bundle. The scanning unit 9 and the light emitting unit 3 perform scanning simultaneously. While light is incident on a fiber (F1, F2, F3, etc.), a partial region (A1, A2, A3, etc.) corresponding to the fiber is scanned. During each scan, the scanning position (scanning point) moves within the corresponding partial area (A1, A2, A3, etc.) without any problem. In FIG. 1, the reference scanning positions (P1, P2, P3) and the other scanning positions (P1 ′, P2 ′, P3 ′) are shown as an example. The reference scanning position corresponds to a scanning point where light from the fiber core reaches when the scanning unit 9 is not operating. The other scanning position is a point where light from the scanning unit 9 reaches when the scanning unit 9 is operating. Each partial region is adjacent so that it does not overlap or only a part overlaps.

  The scanning unit 9 includes two electro-optic elements (EO) 9a and 9b that perform deflection operations in directions perpendicular to each other. The electro-optic elements 9a and 9b are composed of an electro-optic crystal. When the polarization direction of light and the direction of voltage are parallel, the deflection angle of the electro-optic element becomes large. For this reason, the polarization direction of light is adjusted by the polarizing plate 19 or the like. Furthermore, a λ / 2 plate 21 is provided between the two electro-optic elements 9a and 9b to change the polarization direction of light.

  The controller (control unit, control means) 15 controls the deflection operation in the Y-axis direction in the YZ plane by applying a voltage Vy in the Y-axis direction to the electrode of the electro-optical element 9a at the subsequent stage. The controller 15 (control unit) controls the deflection operation in the X-axis direction in the X-Z plane by applying a voltage Vx in the X-axis direction to the electrode of the electro-optic element 9b at the previous stage. The Z axis indicates coordinates in the optical axis direction. Since the controller 15 changes the voltages Vx and Vy, the scanning position can be moved two-dimensionally in the XY plane, so that the scanning unit 9 can perform two-dimensional scanning. The controller 15 has two voltage generators for generating the voltages Vx and Vy.

  Return light (that is, reflected light and scattered light) from the scanning target region 100 of the illuminated object is guided to the spectroscope 32 of the signal processing unit 300 and is received by the photodetector 33 for each wavelength. The spectroscope 32 separates the light from the detection optical fiber 30 into each color. The photodetector 33 detects (samples) the intensity of the return light from each scanning position (sampling position) through the detection optical fiber 30 and the spectroscope 32. The detector 33 includes detectors for each color (red detector 33a, green detector 33b, blue detector 33c, etc.). The output of the photodetector 33 has a one-to-one correspondence with the scanning position that is the illuminated area.

  Time-series detection data (that is, light intensity signal) from the photodetector 33 is stored and stored for each wavelength in the memory 34 (RAM or the like) as image data of the scanning target region 100. For example, the photodetector 33 may generate a light intensity signal in accordance with the sampling signal sent from the controller 15 at each sampling time and output it to the memory 34. The sampling time is a time at which the photodetector 33 should perform sampling, and may be determined for each wavelength as described later. The memory of the controller 15 may store the sampling time for each wavelength. Alternatively, the photodetector 33 may include a control unit having its own memory, the memory may store a sampling time for each wavelength, and the control unit of the photodetector 33 may generate a sampling signal at the sampling time. .

  The light intensity signal of each color stored in the memory 34 corresponds to the pixel value of the pixel of the object. Therefore, the surface information of the scanning target region 100 can be output as an image by displaying the intensity signal in time series on the monitor 35 as a display device. The image data from the memory 34 is output / displayed on a monitor 35 as an image display device according to a command from the controller 15. The controller 15 delays the timing of outputting the intensity signal of each wavelength stored in the memory 34 to the monitor 35 from the time stored in the memory 34 for light data having a shorter wavelength. That is, the controller 15 sets the elapsed time Tp from when the signal is read by the memory 34 until the controller 15 displays the intensity signal on the monitor 35 as the wavelength of the dispersed light is shorter.

  As shown in FIG. 2, the difference in scanning position depending on the wavelength of light will be described using blue light and red light as examples of light having a short wavelength and light having a long wavelength. Here, red light is an example of light having the maximum wavelength of the light source 1, and blue light is an example of light having a wavelength other than the maximum wavelength.

  Due to refractive index dispersion, the refractive index is small for red light and large for blue light. Therefore, when the applied voltages Vx and Vy to the electro-optic elements 9a and 9b are the same, the scanning position by red light (point A) is positioned closer to the optical axis side than the scanning position by blue light (point B) as shown in FIG. is doing. When the return light signal from the point A and the return light signal from the point B are displayed on the monitor 35 at the same timing, a color shift occurs.

For this reason, in the present embodiment, the controller 15 sets the elapsed time Tp from when the memory 34 reads the signal until the monitor 35 displays the signal to be longer as the wavelength of the dispersed light is shorter. As a result, the intensity signals of blue light and red light from the same scanning position can be displayed on the monitor 35 at the same time. The difference in elapsed time (Tp) between the blue light and the red light is from when the blue light irradiates a predetermined position (for example, point A) to when the red light irradiates the predetermined position (for example, point A). The delay time Δt _m . That is, assuming that the elapsed time Tp (λb) for blue light and the elapsed time Tp (λr) for red light, Tp (λb) −Tp (λr) = Δt _m holds for the m-th sampling.

  FIG. 3 is a diagram for explaining how a light beam bends in an electro-optic element (electro-optic crystal). For simplicity, only the electro-optic element 9a for Y-axis scanning will be described in FIG. 3, but the same applies to the electro-optic element 9b for X-axis scanning. The Y axis shows the coordinates of the direction of the electric field depending on the applied voltage V (= Vy). The light incident surface of the electro-optic element is the XY plane. The coordinate Y increases from the voltage electrode 20a toward the ground electrode 20b.

  An applied voltage V from the power source is applied to the electro-optical element 9a via the electrodes (voltage electrode 20a and ground electrode 20b). FIG. 3 shows a case where the applied voltage V applied to the electro-optic element is positive.

By applying a voltage to the electro-optic element, a refractive index distribution (refractive index distribution) is generated due to the Kerr effect or the like. The Kerr effect is a phenomenon in which birefringence occurs when an electric field is applied to an isotropic material, and the refractive index change is proportional to the square of the electric field generated inside. Due to the refractive index distribution, the light incident on the electro-optic element is bent and emitted from the electro-optic element. Further, the refractive index distribution changes depending on the applied voltage. For this reason, by changing the voltage applied to the electro-optical element, the emission angle θ of the light beam emitted from the electro-optical element changes. Further, by changing the applied voltage V, it is possible to move the spot (scanning point) of the light applied to the object. It is possible to obtain a large refractive index gradient by inclining the electric field in the direction of the applied voltage by generating an electric charge in an electro-optic element (for example, KTa _1-x Nb _x O ₃ ) by current injection. (See JP 2008-158325 A, JP 2007-310104 A, etc.).

In the following Example 1 and Example 2, the case where the electro-optic element is KTa _1-x Nb _x O ₃ will be specifically described.

Example 1
When the electro-optic element is KTa _1-x Nb _x O ₃ , the light emission angle θ from the electro-optic element with respect to the optical axis Z is approximately proportional to the square of the applied voltage V as shown in the following formula (1). (See Appl. Phys. Lett. 89, 131115 (2006)).

Here, kθ is a proportional coefficient determined by the size and characteristics of the electro-optic crystal and depends on the incident wavelength.

Therefore, as shown in FIG. 4, the way the light bends differs depending on the wavelength. In FIG. 4, kθ _R is a coefficient kθ (λ) with respect to red light, and kθ _B is a coefficient kθ (λ) with respect to blue light, and the dependency of the applied voltage V on the emission angle θ is illustrated. Since the deflection angle α of the light emitted from the lens group 13 with respect to the optical axis Z is proportional to the emission angle θ, the deflection angle α is also proportional to the square of the applied voltage V. Note that red light is shown as light of the maximum wavelength of the light source 1, and blue light is shown as an example of light of other wavelengths.

  In Example 1, the applied voltage V is repeatedly applied to the electro-optic crystal as shown in FIG. That is, the voltage V is applied as shown in Equation (2).

However, in Formula (2), time t is set to zero at the scanning start time. Assuming that the applied voltage V reaches the maximum value V ₀ at time t ₀ , k _v is expressed as Equation (3).

  From Expression (1) and Expression (2), the emission angle θ and time t are expressed by Expression (4).

Note that k depends on the wavelength λ of the incident light to the electro-optic crystal.

Therefore, in order to perform sampling so that the emission angles θ (that is, deflection angles α) are evenly spaced, the sampling times t ₁ (λ), t ₂ (λ), It is sufficient to detect the return light from the object at the time t ₃ (λ),. Since the sampling time is based on the start time of scanning, the sampling time is expressed with respect to the scanning start time for scanning with light of each color even in the case of the frame sequential method.

In FIG. 6, sampling times t ₁ , t ₂ and t ₃ for detecting red light (wavelength λr) are t ₁ = t ₁ (λr), t ₂ = t ₂ (λr), t ₃ = t ₃ ( λr), and sampling times t ₁ ′, t ₂ ′, t ₃ ′ for detecting blue light (wavelength λb) are t ₁ ′ = t ₁ (λb), t ₂ ′ = t ₂ (λb), t ₃ '= t ₃ (λb).

Here, assuming that the interval of the emission angle θ is Δθ and m is the number of samples (m = 0, 1, 2,...), The sampling time t _m (λ) is expressed by the following equation (5).

In the first embodiment, the sampling time interval t _{m + 1} (λ) −t _m (λ) is a constant value Δθ / k (λ) for each wavelength.

Since the coefficient k = k (λ) depends on the wavelength λ of light incident on the electro-optic crystal, the sampling time t _m (λ) and the sampling time interval Δθ / k (λ) also depend on the wavelength λ. As described above, in order to detect the intensity signal from the scanning position illuminated at the same emission angle θ even if the wavelengths are different, the sampling time and the sampling time interval may be changed for each light wavelength λ. Further, in order to simultaneously display the intensity signal from the same scanning position on the monitor 35 even if the wavelengths are different, the image display timing after the memory acquires the image by the delay time Δt _m depending on the wavelength λ. You can shift it.

For example, the delay time Δt _m of the blue light with respect to the red light having the maximum wavelength is expressed by Equation (6).

Here, k _R = k (λr), k _B = k (λb), and k _R <k _B. The delay time Δt _m increases as k (λ) increases as the wavelength of light having no maximum wavelength is shorter.

Regarding the elapsed time Tp from when the signal is read by the memory 34 until the monitor 35 displays the signal, the elapsed time for blue light (light other than the maximum wavelength) is Tp (λb), and for red light (light with the maximum wavelength). The elapsed time is expressed as Tp (λr). In this case, Tp (λb) −Tp (λr) = Δt _m holds for the m-th sampling. Since the delay time Δt _m increases as the wavelength of light other than the maximum wavelength is shorter, the elapsed time Tp is set longer as the wavelength of the dispersed light is shorter.

-Example 2-
In the second embodiment, as shown in FIG. 7, the voltage V is applied in proportion to the time t. That is, the voltage V is applied as shown in Equation (7).

However, the time t is set to zero at the scanning start time.

  Therefore, the relationship between the emission angle θ and the time t is expressed by Expression (8).

Note that k depends on the wavelength λ of the incident light to the electro-optic crystal.

Therefore, in order to perform sampling so that the emission angles θ (that is, the deflection angles α) are evenly spaced, the sampling times t ₁ (λ), t ₂ (λ), Return light from the object is detected at time t ₃ (λ),. In FIG. 8, sampling times t ₁ , t ₂ and t ₃ for detecting red light (wavelength λr) are t ₁ = t ₁ (λr), t ₂ = t ₂ (λr), and t ₃ = t ₃ ( λr), and sampling times t ₁ ′, t ₂ ′, t ₃ ′ for detecting blue light (wavelength λb) are t ₁ ′ = t ₁ (λb), t ₂ ′ = t ₂ (λb), t ₃ '= t ₃ (λb).

Here, if the interval of the emission angle θ is Δθ, and m is the number of samples (m = 0, 1, 2,...), The sampling time t _m (λ) is expressed by the following equation (9).

In the second embodiment, the sampling time interval t _{m + 1} (λ) −t _m (λ) is not a constant value, but changes according to the number of times of sampling m.

Here, since the coefficient k = k (λ) depends on the wavelength λ of the incident light to the electro-optic crystal, the sampling time t _m (λ) and the sampling time interval t _{m + 1} (λ) −t _m (λ ) Also depends on the wavelength λ. As described above, in order to detect the intensity signal from the scanning position illuminated at the same emission angle θ even if the wavelengths are different, the sampling time and the sampling time interval are changed for each light wavelength λ (for each color). Good. Further, in order to simultaneously display the intensity signal from the same scanning position on the monitor 35 even if the wavelengths are different, the image display timing after the memory acquires the image by the delay time Δt _m depending on the wavelength λ. You can shift it.

For example, the delay time Δt _m of the blue light with respect to the red light having the longest wavelength is expressed by Expression (10).

Here, k _R = k (λr), k _B = k (λb), and k _R <k _B. The delay time Δt _m increases as the wavelength of light having no maximum wavelength is shorter.

Regarding the elapsed time Tp from when the signal is read by the memory 34 until the monitor 35 displays the signal, the elapsed time for blue light (light other than the maximum wavelength) is Tp (λb), and for red light (light with the maximum wavelength). The elapsed time is expressed as Tp (λr). In this case, Tp (λb) −Tp (λr) = Δt _m holds for the m-th sampling. Since the delay time Δt _m increases as the wavelength of light other than the maximum wavelength is shorter, the elapsed time Tp is set longer as the wavelength of the dispersed light is shorter.

In the first and second embodiments, the case where the emission angle θ is proportional to the square of the applied voltage V as shown in Equation (1) is shown, but the same applies even when the relationship between the emission angle θ and the applied voltage V is different from this. In addition, the sampling time t _m (λ) and the delay time Δt _m can be obtained. For example, even when the emission angle θ is proportional to the applied voltage V, the sampling time t _m (λ) and the delay time Δt _m can be obtained similarly.

The action-effect image forming apparatus receives light separated by the spectroscopic unit 32 and generates a signal corresponding to the intensity of light detected at a plurality of sampling times t _m (λ), and this signal. And a memory 34 for reading. Further, the image forming apparatus includes a control unit 15 that reads a signal from the memory 34, forms an image of the target area, and displays the image on the display device 35.

The sampling time interval (t _{m + 1} (λ) −t _m (λ)) of the photodetector changes according to the wavelength of the dispersed light. Thereby, the scanning position (sampling position) on the target region and the interval can be made the same regardless of the color of light. Further, the control unit 15 changes the elapsed time (Tp) from when the memory 34 reads the signal until the control unit displays the signal on the display device 35 according to the wavelength of the dispersed light. Thereby, the light signals of the respective colors from the same scanning position can be displayed at the same time, and the color shift of the image displayed on the display device can be prevented.

  The control unit sets the elapsed time (Tp) to be longer as the wavelength of the dispersed light is shorter. As a result, the shorter the wavelength of the dispersed light, the later the timing at which the signal is displayed on the display device with reference to the time when the memory 34 reads the signal, and the color shift of the image displayed on the display device accurately. Can be prevented.

  Since the scanning optical system includes the electro-optical elements 9a and 9b in which the distribution of the refractive index generated inside changes in accordance with the magnitude of the applied voltage, the image forming apparatus can be easily controlled by controlling the applied voltage of the control unit. The area can be scanned.

The sampling time interval (t _{m + 1} (λ) −t _m (λ)) varies with the number of samplings m. Thus, even when the emission angle θ is not proportional to the time t, sampling can be performed at a constant emission angle interval Δθ, and the intervals of the scanning positions (sampling positions) on the target region can be made uniform.

Since the sampling time interval (t _{m + 1} (λ) -t _m (λ)) increases as the wavelength of the dispersed light becomes longer, the interval between the scanning positions (sampling positions) on the target region is the light It can be exactly the same regardless of the color.

The difference in elapsed time (Tp (λ ′) − Tp (λ)) between the light of a certain wavelength λ ′ and the light of another wavelength λ with respect to the predetermined number of times (m) -th sampling It is equal to the time difference (Δt _m ) of the sampling time with reference to the scanning start time. Thereby, the color shift of the image displayed on the display device can be reliably prevented.

<Second embodiment>
As shown in FIG. 9, not only the electro-optical element but also a scanning optical system having a general magnification chromatic aberration can prevent color misregistration as in the first embodiment.

  In FIG. 9, the light emission part 3 is the structure which scans the scanning object area | region 100 directly. For this reason, unlike the first embodiment, the fiber bundle 7 and the scanning unit 9 do not exist. The scanning optical system 60 includes the light emitting unit 3 and the lens group 13 and has lateral chromatic aberration. The signal processing unit of the second embodiment is the same as that of the first embodiment.

For the scanning optical system 60, the time dependency of the emission angle θ (that is, the deflection angle) depending on the wavelength as shown in Equations (4) and (8) is found from experiments and simulations. Therefore, as in the first embodiment, the sampling time t _m (λ) for sampling so that the emission angles θ are equally spaced can be obtained. When an image is formed and displayed, a delay time Δt _m for preventing color misregistration of the image can be obtained for each color. The controller 15 delays the timing to output the intensity signal of each wavelength to the monitor 35 after being stored in the memory 34 by the delay time Δt _m . The delay time Δt _m is set longer for light data having a shorter wavelength.

  In 2nd embodiment, there exists an effect similar to 1st embodiment.

  In addition, in said 1st and 2nd embodiment, the case where the light emission part 3 was comprised from the galvanometer mirror as a scanning means was described. However, the light emission part 3 may be comprised from the digital mirror device as a scanning means. The light emitting unit 3 is composed of an LED (light emitting diode) array or an LD (laser diode) array arranged to face the optical fiber, and selectively enters light into any one of the optical fibers of the fiber bundle. May be. Moreover, the light emission part 3 is comprised from the single optical fiber which displaces oscillatingly, and light may selectively inject into any one optical fiber of a fiber bundle.

  Moreover, in said 1st and 2nd embodiment, the case where the scanning part 9 was comprised from the electro-optical element was described. However, the scanning unit 9 may be configured by means for scanning the distal end of the fiber bundle. The scanning unit 9 may be configured by a scanning unit such as a displaceable eccentric lens, an acoustooptic device, and a MEMS (micro-electro-mechanical system) mirror. The decentered lens can be moved in the direction perpendicular to the optical axis or tilted with respect to the optical axis to deflect light.

  The present invention is not limited to the first and second embodiments described above, and it is obvious that various modifications can be made within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Light source 3 Light emission part 3a, 3b Galvano mirror 5, 11, 13 Lens group 7 Fiber bundle 9 Scanning part 9a, 9b Electro-optic element 15 Controller (control part, control means)
20a Voltage electrode 20b Ground electrode 32 Spectrometer (spectrometer, spectroscopic means)
33 Photodetector (photodetector, photodetection means)
34 Memory (storage medium)
35 Monitor (display device)
40, 60 Scanning optical system 100 Scan target area 200 Optical scanning device 300 Signal processing unit

Claims (7)

A light source;
A scanning optical system that scans and illuminates a target area with light from the light source;
A spectroscopic unit that splits light from the target region;
A photodetector that receives the light split by the spectroscopic unit and generates a signal corresponding to the intensity of the detected light at a plurality of sampling times;
A memory for reading the signal;
A control unit that reads a signal from the memory, forms an image of the target area, and displays the image on a display device;
The sampling time interval of the photodetector varies with the wavelength of the split light,
The image forming apparatus, wherein the control unit changes an elapsed time from when the memory reads a signal until the control unit displays the signal on the display device according to a wavelength of the dispersed light. .   The image forming apparatus according to claim 1, wherein the control unit sets the elapsed time to be longer as the wavelength of the dispersed light is shorter.   The image forming apparatus according to claim 1, wherein the scanning optical system includes an electro-optical element in which a distribution of a refractive index generated therein changes according to a magnitude of an applied voltage.   The image forming apparatus according to claim 1, wherein the scanning optical system has lateral chromatic aberration.   The image forming apparatus according to claim 1, wherein the sampling time interval varies with the number of samplings.   The image forming apparatus according to claim 1, wherein an interval of the sampling time is increased as a wavelength of the dispersed light is longer.   Regarding the predetermined number of times of sampling, the difference in elapsed time between light of a certain wavelength and light of another wavelength is equal to the time difference of the sampling time with reference to the scanning start time of the scanning optical system. The image forming apparatus according to claim 1, wherein:

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