JP2010223814A - Photodetection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photodetection device for improving sensitivity for detecting light by reducing background light or ASE (Amplified Spontaneous Emission). <P>SOLUTION: A wavelength-swept light generation-application means 10 generates wavelength-swept light of which the wavelength of light in a narrow band is varied over a wide band in terms of time, and irradiates a measurement target 20 with the wavelength-swept light. An optical amplification means 30 amplifies the light obtained from the measurement target 20 by applying the wavelength-swept light. A wavelength-swept light filtering means 40 receives light amplified by the optical amplification means 30 and continuously varies the light over a transmission wavelength band in terms of time. In this case, a control means 60 controls the wavelength-swept light filtering means 40 so that light which includes a wavelength band of wavelength-swept light emitted from the wavelength-swept light generation-application means 10 and which is in a band equal to or slightly wider than the band is transmitted therethrough, and removes background light or ASE that is not in the transmission wavelength band. Light transmitted through the wavelength-swept light filtering means 40 is converted to electric signals by a photoelectric conversion means 50 for processing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light detection device used in living body observation and the like.

  In the medical field and scientific field, living body observation technology using light such as an endoscope and a microscope plays an important role. In living body observation using light, in many cases, an observation sample is irradiated with light, and reflected light, transmitted light, scattered light, or the like obtained thereby is observed.

  However, since a living body is easily damaged by light irradiation, there is an upper limit to the amount of illumination light and excitation light that can be irradiated to a biological sample. Moreover, since the state and shape of the living body change from moment to moment, it is necessary to detect light at high speed in order to perform accurate observation. Therefore, an optical signal obtained in living body observation is usually a weak signal.

  On the other hand, when observing a living body using an endoscope, a microscope, etc., a background caused by glass materials contained in the optical system such as a lens used, autofluorescence emitted from cells, tissues or secretions to be observed, and stray light Light becomes noise and causes a decrease in detection sensitivity. Although autofluorescence emitted from the glass material can be taken by changing the glass material, it is difficult to completely remove the autofluorescence.

  For example, an optical filter that removes light having an autofluorescence wavelength can be used to remove autofluorescence from cells, tissues, secretions, and the like. However, even if an optical filter is used, it is difficult to completely remove autofluorescence. In particular, when white light is used as illumination light, the wavelength of the optical signal to be detected and the wavelength of autofluorescence are covered, and thus cannot be removed by an optical filter.

  For background light such as stray light, measures such as observation in a dark room are taken. However, when such measures are taken, the environment in which living body observation can be performed is very limited.

  That is, in living body observation, the obtained optical signal is weak, but the stray light due to autofluorescence or irradiation light from a sample or the like becomes noise, and it is difficult to remove these noises. It is a problem that it is difficult to obtain the detection sensitivity.

  On the other hand, with the aim of improving detection sensitivity, a configuration in which an optical amplifier is disposed in front of a light receiving element is disclosed (for example, see Patent Document 1). However, when an optical amplifier is used, it is difficult to improve detection sensitivity because amplified spontaneous emission (ASE) noise generated from the optical amplifier becomes large background light.

JP-A-2-189478

  Accordingly, an object of the present invention, which has been made paying attention to these points, is to provide a photodetection device with improved photodetection sensitivity.

The invention of the photodetection device according to claim 1 that achieves the above object is as follows:
A wavelength swept light generating / irradiating means for generating a wavelength swept light whose time band is changed, and irradiating the wavelength swept light to a measurement object;
Wavelength-swept light filtering means that receives light obtained from the measurement object by irradiation of the wavelength-swept light by the wavelength-swept light generation / irradiation means, and transmits the light by continuously changing the transmission wavelength band over time; ,
Photoelectric conversion means for converting the light transmitted through the wavelength swept light filtering means into an electrical signal;
The wavelength sweep time in the wavelength sweep light generation / irradiation means is transmitted so that the wavelength sweep light filtering means transmits light in a band including the wavelength band of the wavelength sweep light emitted from the wavelength sweep light generation / irradiation means. Control means for controlling in synchronization with the change;
It is characterized by comprising.

The invention according to claim 2 is the light detection device according to claim 1,
An optical amplifying means for amplifying the light obtained from the measurement object is provided in the preceding stage of the wavelength swept light filtering means.

The invention of the photodetection device according to claim 3 that achieves the above object is as follows:
A wavelength swept light generating / irradiating means for generating a wavelength swept light whose time band is changed, and irradiating the wavelength swept light to a measurement object;
Irradiation of the wavelength swept light by the wavelength swept light generation / irradiation means receives light from a plurality of different positions of the measurement object, and continuously changes the transmission wavelength band over time. A plurality of wavelength swept optical filtering means to be transmitted;
Photoelectric conversion means for converting the light transmitted through each of the plurality of wavelength swept light filtering means into an electrical signal;
A wavelength band in the wavelength swept light generating / irradiating means so that the plurality of wavelength swept light filtering means transmits light in a band including the wavelength band of the wavelength swept light emitted from the wavelength swept light generating / irradiating means. Control means for controlling each of them in synchronism with time changes,
It is characterized by comprising.

The invention according to claim 4 is the light detection device according to claim 3,
A plurality of light amplifying means for amplifying the plurality of lights obtained from the measurement object are provided in the preceding stage of the plurality of wavelength swept light filtering means, respectively.

The invention of a photodetection device according to claim 5 that achieves the above object is as follows:
A plurality of wavelength swept light generating / irradiating means for generating a wavelength swept light whose time band is changed, and irradiating the wavelength swept light to a measurement object;
Each of the plurality of wavelength swept light generation / irradiation means is provided correspondingly, and receives the light obtained from the measurement object by irradiation of the wavelength swept light by the corresponding wavelength sweep light generation / irradiation means. A plurality of wavelength swept optical filtering means for continuously changing the transmission wavelength band with time, and transmitting the wavelength band;
Optical multiplexing means for multiplexing light transmitted through each of the plurality of wavelength swept light filtering means;
Photoelectric conversion means for converting the light combined by the optical combining means into an electrical signal;
The plurality of wavelength swept light filtering means transmit the corresponding wavelength swept light generation / irradiation so as to transmit light in a band including the wavelength band of the wavelength swept light emitted from the corresponding wavelength swept light generation / irradiation means. Control means for controlling each of them in synchronism with time variation of the wavelength band in the means;
It is characterized by comprising.

The invention according to claim 6 is the light detection device according to claim 5,
A plurality of optical amplifying means for amplifying the light obtained from the measurement object is provided in the preceding stage of each of the plurality of wavelength swept optical filtering means.

The invention according to claim 7 is the photodetector according to any one of claims 1 to 6,
The photoelectric conversion means is characterized in that the light is electrically integrated and output at a cycle that is the same as or longer than the sweep cycle of the wavelength sweep light generation / irradiation means.

  According to the present invention, the wavelength swept light generating / irradiating means generates wavelength swept light whose wavelength is continuously changed, and the wavelength swept light filtering means is a wavelength swept light emitted from the wavelength swept light generating / irradiating means. Since an optical signal including the wavelength of light is transmitted, the sensitivity of light detection can be improved.

1 is a block diagram showing a schematic configuration of a photodetection device according to a first embodiment of the present invention. It is a figure explaining the light detection operation | movement by the conventional photon detection apparatus using the white light source as a comparative example. It is a figure explaining operation | movement of the photon detection apparatus of 1st Embodiment. It is another figure explaining operation | movement of the photon detection apparatus of 1st Embodiment. It is a figure which shows schematic structure figure of the scanning endoscope which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of a Pr addition fluoride fiber type | mold amplifier. It is a block diagram which shows schematic structure of the photon detection apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows schematic structure of the highly sensitive endoscope which concerns on 4th Embodiment of this invention. It is a block diagram which shows schematic structure of the photon detection apparatus which concerns on 5th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of the photodetection device according to the first embodiment of the present invention. This light detection device is for irradiating a measurement target with illumination light, photoelectrically converting the obtained light, and delivering it to a signal processing system as an electrical signal.

  The light detection apparatus according to the present embodiment generates a wavelength swept light whose wavelength band is changed over time, a wavelength swept light generation / irradiation means 10 that irradiates the measurement target 20 with the wavelength swept light, and a wavelength swept light generation. The light amplifying means 30 that amplifies the light obtained from the measurement object 20 by the irradiation of the wavelength swept light by the irradiation means 10 and the light amplified by the light amplifying means 30 are received, and the transmission wavelength band is continuously changed over time. The wavelength swept light filtering means 40 to be transmitted, the photoelectric conversion means 50 for converting the light transmitted through the wavelength swept light filtering means into an electric signal, and the wavelength swept light filtering means 40 are converted into the wavelength swept light generating / irradiating means 10. Control that synchronizes with the time change of the wavelength band in the wavelength sweep light generation / irradiation means 10 so as to transmit the light in the band including the wavelength band of the wavelength sweep light emitted from And a stage 60.

  The wavelength swept light generation / irradiation means 10 is capable of sweeping a wavelength in a wide band and uses a light source having a narrow instantaneous line width compared to the swept bandwidth, such as a rare earth-doped fiber laser, a dye laser, or a semiconductor laser. A tunable laser, a swept laser, or a light source that generates a chirp pulse. Further, the wavelength swept light generating / irradiating means 10 has an illumination optical system that irradiates the wavelength swept light emitted from the light source as illumination light to a desired detection position of the measurement target 20, which is a biological sample, for example.

  The optical amplifying means 30 receives and amplifies the light transmitted, reflected or scattered by the measurement object 20, and is a rare earth doped fiber type optical amplifier, Raman amplifier, inductive parametric amplifier, semiconductor optical amplifier. Or an amplifier such as a dye amplifier. The wavelength sweep light filtering means 40 is a narrow band wavelength sweep optical filter that transmits a wavelength band having a width that is the same as or slightly wider than the instantaneous line width of the illumination light generated by the wavelength sweep light generation / irradiation means 10. For example, it includes a filter having a wavelength variable characteristic such as a dielectric multilayer filter, a Fabry-Perot filter, a spectral filter, an interference filter, or a fiber Bragg grating filter. The photoelectric conversion means 50 electrically integrates the light output from the wavelength swept light filtering means and outputs it as an electrical signal. This integration time is the same as or longer than the sweep cycle of the wavelength sweep light generation / irradiation means. As the photoelectric conversion means 50, for example, a PMT (Photo multiplier tube), an APD (Avalanche photo diode), or a PD (Photo diode) is used. The electrical signal output from the photoelectric conversion means 50 is input to the signal processing system and processed.

  The control unit 60 controls the wavelength sweep light generation / irradiation unit 10 and the wavelength sweep light filtering unit 40 to sweep the wavelength of illumination light emitted from the wavelength sweep light generation / irradiation unit 10 within a predetermined wavelength range. The time variation of the wavelength band of the wavelength sweep light generation / irradiation means 10 so that the transmission wavelength band of the wavelength sweep light filtering means 40 includes the wavelength band of the wavelength sweep light emitted from the wavelength sweep light generation / irradiation means 10 Change in sync with. This control means 60 is comprised including a computer or DSP, for example.

  Next, the operation of the photodetecting device according to the first embodiment will be described with reference to FIGS.

  First, for comparison, noise removal in a photodetection device using a conventionally used white light source will be described. FIG. 2 is a diagram illustrating an example of light detection by a conventional light detection device using a white light source. In this example, the measurement object is irradiated with white light having the wavelength intensity distribution shown in FIG. The white light irradiated to the measurement target is transmitted, reflected, or scattered by the measurement target, and the signal light 101 and the background light 102 having the wavelength intensity distribution shown in FIG. 2B are obtained. In order to improve the S / N ratio, when passing through an optical bandpass filter having a wavelength characteristic diagram 2 (c) that transmits only the wavelength band of the irradiated white light, the wavelength intensity distribution of the non-detection light is as shown in FIG. 2 (d). As shown. However, as can be seen from FIG. 2 (d), when white light is used as illumination light, it is impossible to remove background light in the same band as the irradiated light only by using an optical bandpass filter. The SN ratio cannot be improved sufficiently.

  Next, noise removal by the photodetecting device of the present embodiment will be described. FIG. 3 is a diagram for explaining the operation of the photodetecting device according to the first embodiment. Under the control of the control unit 60, the wavelength sweep light generation / irradiation unit 10 emits illumination light that has been swept in a wide band, that is, whose wavelength has been continuously changed. FIG. 3A is a diagram showing the wavelength light intensity distribution of the illumination light emitted from the wavelength sweep light generation / irradiation means 10 during the sweep time T. FIG. In this figure, narrow-band waveforms displayed with numbers 1, 2, 3, and 4 indicate the instantaneous light spectrum of the illumination light. As shown in this figure, the illumination light continuously changes with time, for example, from a short wavelength to a long wavelength during the sweep time T. This wavelength sweep is repeated with the sweep period as T.

  When this illumination light is irradiated onto the measurement object, light as shown in FIG. 3B is obtained. The waveforms indicated by 1, 2, 3 and 4 in FIG. 3B are signal lights obtained by the instantaneous illumination light indicated by the same numbers in FIG. On the other hand, FIG. 3B includes background light other than signal light such as autofluorescence and stray light generated from a glass material or a living body. When the signal light is to be detected using an accumulation type photoelectric conversion element having an integration period longer than the sweep time T as the photoelectric conversion means 50 without filtering by the wavelength sweep light filtering means 40, the signal light Is obtained as an integrated value over the integration period of the photoelectric conversion element. On the other hand, the noise component due to the background light is also obtained as an integrated value during the integration period, but the background light is present over the entire sweep time T, so the integrated value becomes large. For this reason, even if the signal light is larger than the background light instantaneously, the detection sensitivity by the photoelectric conversion element cannot be increased. That is, simply sweeping the illumination light is equivalent to irradiating the measurement target 20 with white light as shown in FIG. 3 (b '), and no improvement in the SN ratio is observed.

  Therefore, in the present embodiment, the light obtained from the measurement target 20 is transmitted by the wavelength swept light filtering means 40 so that only light in a band that is the same as or slightly wider than the illumination light is transmitted. The wavelength sweep light filtering means 40 transmits light in a narrow transmission wavelength band including the wavelength of the input signal light in synchronization with the wavelength sweep light generation / irradiation means 10 under the control of the control means 60. As shown in FIG. 5C, the transmission wavelength band is dynamically changed so as to remove light other than the transmission wavelength band. Thereby, the light transmitted through the wavelength sweeping light filtering means 40 has an instantaneous wavelength light intensity distribution as shown in FIG. Since the autofluorescence generated from the glass material or the living body is generated on the longer wavelength side than the illumination light, the autofluorescence is removed by the wavelength swept light filtering means 40. Further, since the transmission wavelength band of the wavelength swept light filtering means 40 is limited to a narrow band at each time point, background light such as stray light that cannot pass through the wavelength transmission band described above is significantly removed. As a result, the light detected by the photoelectric conversion means 50 is equivalent to a case where white light is irradiated and background light is greatly reduced as shown in FIG.

  FIG. 4 is an explanatory diagram for explaining the operation of the photodetecting device according to the first embodiment from another viewpoint. FIG. 4A shows the time change of the wavelength band of the light irradiated on the measurement target 20 by the wavelength sweep light generation / irradiation means 10. As shown in FIG. 4A, the wavelength of the wavelength sweep light changes from a short wavelength to a long wavelength over time during the sweep time T. FIG. 4B shows light obtained from the measurement object 20 by irradiation with the wavelength sweeping light. As shown in FIG. 4B, the measurement object obtains the signal light 101 whose wavelength changes with time similarly to the change of the wavelength of the illumination light and the background light 102 generated in a wide band without depending on time. It is done. On the other hand, the wavelength swept light filtering means 40 is a filter that transmits a narrow band wavelength including the wavelength band of the wavelength swept light, so that only the light within the time-varying wavelength band indicated by the broken line in FIG. Has characteristics. Therefore, only the signal light 101 and the background light 102 in the portion shown in FIG. 4D are transmitted through the wavelength swept light filtering means 40 and are incident on the photoelectric conversion means 50. That is, the background light which becomes a noise component is largely removed by the wavelength sweep light filtering means 40.

  Further, in the present embodiment, the optical amplifying means 30 is provided before the wavelength swept optical filtering means 40. The light amplifying means 30 amplifies light obtained by irradiating the measurement target 20 with illumination light and generates spontaneous emission (ASE) noise within the gain band. Similar to the description of the background light removal described above, the wavelength swept light filtering means 40 has a wavelength region having a width that is the same as or slightly wider than the instantaneous line width of the wavelength swept light generated by the wavelength swept light generating / irradiating means 10. Since transmission is performed, ASE other than the transmission wavelength band is removed, and mixing of ASE into the signal light can be minimized.

  As described above, according to the present embodiment, the wavelength sweep light generation / irradiation means 10 irradiates the sample with illumination light as the wavelength sweep light in which the wavelength of the narrow band light is swept in a wide band, and the sample. Whether the wavelength swept light filtering means 40 includes the wavelength band of the wavelength swept light emitted from the wavelength swept light generation / irradiation means 10 and is equivalent to the wavelength band of the wavelength swept light. Since a slightly wide band of light is transmitted, noise components due to background light such as autofluorescence and stray light can be reduced. In addition, since the wavelength swept optical filtering means 40 is disposed after the optical amplifying means 30, the ASE generated by the optical amplifying stage 30 can be similarly removed. Therefore, the detection sensitivity of the light detection device can be greatly improved.

  In addition, according to the present embodiment, the modulation frequency is set to be equal to or longer than the wavelength sweep period of the wavelength sweep light generation / irradiation means 10 and the wavelength sweep light filtering means 40 by adjusting the integration time of the photoelectric conversion means. It is possible to obtain a signal similar to a signal obtained when photoelectrically converting a signal having a wider optical spectrum band than the band. Therefore, after photoelectric conversion, the same processing as when the signal light spectrum band is wider than the conventional signal modulation frequency band can be performed. Furthermore, in normal living body observation, many ASEs are also detected as noise light in order to detect light having a wider signal light spectrum band than the signal modulation frequency band of the photoelectric conversion means. Thus, the detected ASE can be reduced, so that light detection in a wide signal light spectrum band can be performed at high speed and with high sensitivity.

  Furthermore, in the photodetector of this embodiment, the optical spectrum waveform of the optical signal that is photoelectrically converted can be controlled by changing the wavelength sweep pattern. This is very effective for applications where color rendering is important, such as in vivo observation.

(Second Embodiment)
FIG. 5 is a diagram showing a schematic configuration diagram of a scanning endoscope according to the second embodiment of the present invention. This scanning endoscope irradiates the biological sample 21 while scanning illumination light, and performs signal processing on the obtained light to display an image. This scanning endoscope is configured to include components corresponding to the respective components of the photodetecting device shown in FIG. The configuration will be described below.

  The scanning endoscope according to the present embodiment includes a wavelength swept light generation / irradiation means for generating illumination light and irradiating the biological sample 21, and a part for collecting and detecting and processing the light obtained from the biological sample 21 This will be explained separately. First, the wavelength sweep light generation / irradiation means includes a Pr-doped fluoride fiber type wavelength sweep laser 11, an optical isolator (ISO) 12, a single mode fiber (SMF) 13, and a collimator 14. It is configured to include.

  The Pr-doped fluoride fiber type wavelength sweep laser 11 is a laser whose wavelength can be swept in the range of 540 nm to 545 nm, the average output is about 10 mW, the instantaneous line width is 100 MHz or less, and the spatial mode is a single mode. This Pr-doped fluoride fiber type laser 11 is connected to a driver 62 controlled by a computer 61 described later. The output side of the Pr-doped fluoride fiber type laser 11 is connected to an optical isolator (ISO) 12. The ISO 12 is for removing the return light from the latter stage than the ISO 12. The ISO 12 is connected to a collimator 14 via a single mode optical fiber (SMF) 13 that operates in a single mode in a wavelength range of 540 nm to 545 nm. The collimator 14 is fixed to a scanning mount 33 described later, and is configured to irradiate illumination light incident from the SMF 13 to a desired detection position of the biological sample 21 as substantially parallel light.

  Next, a configuration for performing signal processing by collecting and detecting light obtained from the biological sample 21 by irradiation with illumination light will be described. This scanning endoscope includes a condensing lens 32, a scanning mount 33, a tapered fiber (TF) 34, a Pr-doped fluoride fiber optical amplifier 31, an FFP-TF (fiber Fabry-Perot tunable filter) 41, a PD (Photo diode) 51, an electric amplifier 83, an AD (analog-to-digital) converter 84, and a computer 61.

  The condensing lens 32 is disposed adjacent to the collimator 14 on the scanning mount 33 with the incident surface facing the biological sample 21, and the illumination light emitted from the collimator 14 is reflected by the biological sample 21. The light is condensed by the condensing lens 32. The TF 34 is an optical fiber whose core diameter gradually changes from the light input side to the light output side. One end is coupled to the condensing lens 33 and the other end is coupled to the Pr-doped fluoride fiber optical amplifier 31. Yes. In the present embodiment, for example, the input-side core diameter is 200 μm, and the output-side core diameter is 4 μm. This tapered fiber is capable of mode-converting multimode light on the input side to substantially single-mode light on the output side, and substantially matches the amplification spatial mode of the Pr-doped fluoride fiber amplifier 31, It is provided to reduce the loss due to mismatch.

  The Pr-doped fluoride fiber optical amplifier 31 constitutes an optical amplifying means, and amplifies the light incident from the TF 34 with a gain of 15 dB, for example. As shown in FIG. 6, the Pr-doped fluoride fiber amplifier 31 includes an isolator (ISO) 86, a semiconductor laser (LD) 87, a WDM (wavelength division multiplexing) coupler 88, an optical filter 89, and a Pr-doped fluoride fiber 90. And an optical filter 91 and an isolator (ISO) 92.

  For example, the LD 87 is a light source that emits excitation light having a wavelength of 404 nm. The output light intensity of the LD 87 is adjusted by the driver 81. The WDM coupler 88 combines the signal light having a wavelength of 540 nm to 545 nm input via the ISO 86 that removes the return light from the TF 34 and the excitation light having a wavelength of 404 nm emitted from the LD 87 to be longer than the wavelength of 550 nm. The light is output to the Pr-doped fluoride fiber 90 through an optical filter 89 that removes light of a wavelength. The Pr-doped fluoride fiber 90 is a single mode fiber, and amplifies signal light with pumping light.

  Further, the output light from the Pr-doped fluoride fiber 90 is removed by the optical filter 91 through the ISO 92 that removes the excitation light having a wavelength of 404 nm and the light having a wavelength longer than the wavelength 550 nm, and removing the return light. The optical amplifier 31 is configured to output.

  An FFP-TF 41 shown in FIG. 5 is connected to the output side of the Pr-doped fluoride fiber amplifier 31. The FFP-TF 41 constitutes a wavelength swept optical filtering means, and can change the transmission center wavelength in a transmission band of 0.50 nm and a wavelength range of 540 nm to 545 nm, for example. This change in wavelength is controlled by a computer 61 described later via a driver 63. The PD 51 is a photoelectric conversion unit that receives the output of the FFP-TF 41 and converts light into an electrical signal. Further, an electrical amplifier 83, an AD converter 84, and a computer 61 are connected to the subsequent stage of the PD 51.

  The computer 61 constitutes control means, and is a Pr-doped fluoride fiber type wavelength sweep laser 11 driver 62, a Pr-doped fluoride fiber type optical amplifier 31 driver 81, an FFP-TF 41 driver 63, and a scanning mount 33. It is connected to the driver 82 and configured to control them. As a result, the computer 61 allows the FFP-TF 41 to transmit light in a narrow band including the wavelength band of the wavelength-swept light emitted from the Pr-doped fluoride fiber-type wavelength swept laser 11. Control is performed in synchronization with the time change of the wavelength band in the sweep laser 11. The computer 61 also performs processing by associating the position of the scanning mount 33, the wavelength of light emitted from the Pr-doped fluoride fiber type wavelength sweep laser 11, the transmission center wavelength of the FFP-TF 41, and the output signal from the AD converter 84. And the result can be displayed on the display monitor 85.

  With the configuration as described above, in the scanning endoscope according to the present embodiment, the computer 61 controls the scanning mount 33 by the driver 82 to position the detection position of the biological sample 21. Next, the computer 61 controls the Pr-doped fluoride fiber type wavelength sweep laser 11 by the driver 62 to generate wavelength swept light whose wavelength is continuously changed in the wavelength range of 540 nm to 545 nm. The wavelength swept light sweeps one or more wavelengths at a desired position. This wavelength swept light is irradiated as a substantially parallel illumination light from the collimator 14 to the biological sample 21 through the ISO 12 and the SMF 13.

  This illumination light is reflected by the biological sample 21 and collected as signal light by the condensing lens 32 together with background light. The signal light and the background light collected by the condensing lens 32 are input to the TF 34 as multimode light with a disturbed wavefront, the mode state is adjusted by the TF 34, and the Pr-doped fluoride fiber type is used as single mode light. It is input to the optical amplifier 31 and amplified. During this amplification, ASE is generated in the gain band of the Pr-doped fluoride fiber type optical amplifier 31.

  Next, the light emitted from the Pr-doped fluoride fiber optical amplifier 31 is input to the FFP-TF 41. The FFP-TF 41 transmits only light of a wavelength band that includes the wavelength band of the wavelength swept light emitted from the Pr-doped fluoride fiber type wavelength sweep laser 11 under the control of the computer 61 and that is the same or slightly wider than this wavelength band. Therefore, background light and ASE that cannot pass through the FFP-TF 41 are removed.

  Furthermore, the light output from the FFP-TF 41 is photoelectrically converted by the PD 51. The PD 51 integrates light for a time equal to or longer than the sweep period of the wavelength sweep light and outputs an electrical signal. The electric signal output from the PD 51 is amplified by the electric amplifier 83, converted into a digital signal by the AD converter 84, transmitted to the computer 61, and stored. The computer 61 further controls the scanning mount 33 to sequentially scan the detection positions of the biological sample 21, and performs light detection at each detection position as described above. When the scanning of the detection position is completed for the desired detection area, the computer 61 processes the obtained digital signal in association with, for example, the scanning position information of the scanning mount 33 at the time of each detection, and stores it in the monitor 85. Display the endoscopic image.

  As described above, according to the present embodiment, the transmission wavelength band of the light transmitted through the FFP-TF 41 is changed in synchronization with the change in the wavelength of the wavelength swept light by the Pr-doped fluoride fiber type wavelength sweep laser 11. Therefore, background light and ASE can be efficiently removed from the light obtained from the biological sample 21, and the S / N ratio can be improved, and sensitivity limitations due to autofluorescence and stray light can be greatly relaxed. . Thereby, an endoscopic image can be obtained at high speed and with high sensitivity.

(Third embodiment)
FIG. 7 is a block diagram showing a schematic configuration of the photodetecting device according to the third embodiment of the present invention. This light detection device generates a wavelength swept light whose wavelength band is changed over time, and includes a wavelength swept light generation / irradiation means 10 that irradiates the measurement target 20 with the wavelength swept light, and a wavelength swept light generation / irradiation means 10. A plurality of light amplifying means 30 for receiving and amplifying light from a plurality of different positions of the measurement target 20 by irradiation with wavelength swept light, and a plurality of lights output from the light amplifying means 30 with transmission wavelength bands respectively. A plurality of wavelength swept light filtering means 40 that continuously transmit light with a time change, a photoelectric conversion means 50 that converts light transmitted through each of the plurality of wavelength swept light filtering means 40 into an electric signal, and wavelength swept light generation -It is comprised including the control means 60 which controls the irradiation means 10 and the wavelength sweep light filtering means.

  Here, the control unit 60 generates the wavelength swept light so that the plurality of wavelength swept light filtering units 40 transmit light in a band including the wavelength band of the wavelength swept light emitted from the wavelength swept light generating / irradiating unit 10. Control is performed in synchronization with the time change of the wavelength band in the irradiation means 10.

  In the present embodiment, the photoelectric conversion means 50 includes, for example, a CCD (Charged Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), an EM-CCD (Electron multiplying-CCD), and an EB-CCD (Electron Bombardment-CCD). ) Is used. About another structure, it is the same as that of the photon detection apparatus based on 1st Embodiment described in FIG.

  With this configuration, the measurement target 20 is irradiated with illumination light that is a wavelength sweep light from the wavelength sweep light generation / irradiation means 10, and light obtained from a plurality of detection positions of the measurement target 20 is optically amplified in parallel. After the amplification at 30, the wavelength band of the wavelength swept light emitted from the wavelength swept light generation / irradiation means 10 by the plurality of wavelength swept light filtering means 40, and a wavelength band of the same or slightly wider width than this wavelength band Are respectively transmitted and detected by the photoelectric conversion means 50 in parallel. An electrical signal obtained by photoelectric conversion is transmitted to a signal processing system, and processing such as image generation is performed.

  According to the present embodiment, since information from a plurality of detection positions to be measured is detected in parallel, the detection speed of the light detection device and the optical system including the light detection device can be further improved. Accordingly, the present invention can be effectively applied to applications that require high-speed and high-sensitivity detection such as observation of a living body with movement.

(Fourth embodiment)
FIG. 8 is a diagram showing a schematic configuration of a highly sensitive endoscope according to the fourth embodiment of the present invention. This high-sensitivity endoscope irradiates the biological sample 22 with illumination light, and performs parallel signal processing on the light obtained from a plurality of detection positions to display an image. This high-sensitivity endoscope is configured to include components corresponding to the components of the photodetection device shown in FIG. The configuration will be described below.

  First, in the highly sensitive endoscope according to the present embodiment, wavelength swept light generation / irradiation means for generating wavelength swept light and irradiating the biological sample 22 includes the wavelength variable LD 15, ISO 16, SMF 17, and illumination lens. 18.

  The wavelength tunable LD 15 is a laser capable of changing the oscillation wavelength in the range of 630 nm to 645 nm. The average output is about 10 mW, the instantaneous line width is 100 MHz or less, and the spatial mode is a single mode. The wavelength variable LD 15 is connected to a driver 64 controlled by a computer 61 described later. The output side of the wavelength tunable LD 15 is connected to an ISO 16 for removing return light. The ISO 16 is connected to an illumination lens 18 via a single mode optical fiber (SMF) 17 that operates in a single mode in a wavelength range of 630 nm to 645 nm. The illumination lens 18 is fixed to the housing 94 and irradiates a desired observation region of the biological sample 22 in a plane by expanding the laser beam incident from the SMF 17.

  Further, in order to collect and detect light obtained from a plurality of detection positions of the biological sample 22, and to perform signal processing, the high-sensitivity endoscope is provided with a plurality of housings 94 arranged in parallel with each other. Condensing lens 36, a plurality of TFs 37, a plurality of ISOs 38, a plurality of semiconductor amplifiers (SOA) 35, a plurality of ISOs 39 and a plurality of dielectric multilayer bandpass filters (BPF) 42, a CCD 52, and an AD converter 96 And a computer 61. The condensing lenses 36, TF37, ISO38, SOA35, ISO39 and BPF42 are connected in parallel in this order, and the output side of each BPF is connected to the CCD 52.

  The plurality of condensing lenses 36 are fixed to the housing 94 together with the illumination light lens 18 in a state where the incident surfaces are arranged in an array with the biological sample 22 facing the biological sample 22. As a result, the illumination lens 18 spreads the illumination light beam to irradiate the biological sample 22 in a plane, and each condensing lens 36 condenses light from each detection position reflected by the biological sample. It is configured as follows.

  Each TF 37 has the same configuration and function as the TF 34 of the scanning endoscope of FIG. Also, ISO 38 and ISO 39 provided before and after each SOA 35 are for removing the return light. Each SOA 35 constitutes an optical amplifying means and amplifies the light collected by the condensing lens 36 and input via the TF 37 with a gain of 15 dB in a gain band of 625 nm to 650 nm, for example. And output to the BPF 42. Each BPF 42 constitutes a wavelength swept optical filtering means, and can change the transmission center wavelength in a transmission band of 0.60 nm and wavelengths of 630 nm to 645 nm, for example. The outputs of the respective BPFs 42 are output in parallel to the CCD 52 which is a photoelectric conversion means. The CCD 52 converts the optical signal input from the BPF 42 into an electrical signal in parallel and outputs it. The output of the CCD 52 is input to the AD converter 96, converted into a digital signal, and output to the computer 61.

  The computer 61 constitutes control means, and is connected to the wavelength variable LD 15 driver 64, the SOA 35 driver 95, and the BPF 42 driver 65, and is configured to control them. Accordingly, the computer 61 controls the BPF 42 to transmit the wavelength of light emitted from the wavelength variable LD 64. Further, the computer 61 performs processing by associating the wavelength of the wavelength sweeping light emitted from the wavelength tunable LD 15, the transmission center wavelength of the BPF 42, and the output signal from the AD converter 84, and displaying the result on the display monitor 85. it can.

  With the configuration as described above, in the high sensitivity endoscope according to the present embodiment, the computer 61 controls the wavelength variable LD 15 with the driver 64 and continuously changes the wavelength band in the wavelength range of 630 nm to 645 nm. Generates wavelength swept light. This wavelength swept light passes through the ISO 16 and the SMF 17 and is irradiated from the illumination lens 18 to the biological sample 22 as illumination light having an expanded beam.

  This illumination light is reflected by the biological sample 22 and is collected together with background light by each of the plurality of condensing lenses 36. The signal light and background light collected by the respective condensing lenses 32 are input as multimode light with a disturbed wavefront to the TF 37 coupled to each condensing lens, and the mode state is adjusted by the TF 37, respectively. The light is output to the SOA 35 as single mode light. Each SOA 35 amplifies the input light and outputs it. This amplification generates ASE in the gain band of the SOA 35.

  Next, each light emitted from the SOA 35 is input to the BPF 42 coupled to the SOA 35. Each BPF 42 is controlled by the computer 61 via the driver 65, continuously changes the transmission center wavelength, and transmits narrow band light including the band of the wavelength swept light emitted from the wavelength variable LD 15 at each time point. As a result, background light and ASE that cannot be transmitted through the BPF 42 are removed. Further, the light output from each BPF 42 is photoelectrically converted by the CCD 52, converted into a digital signal by the AD converter 96, and processed by the computer 61. The computer 61 displays an endoscopic image on the monitor 85 based on the output signal from the CCD 52.

  As described above, according to the present embodiment, the biological sample 22 is planarly irradiated as the illumination light with the wavelength swept light whose wavelength is continuously changed by the wavelength tunable LD 15 to detect a plurality of biological samples 22. Light is collected from the position, and each light is transmitted through the BPF 42 by changing the transmission wavelength band of the BPF 42 in synchronization with the change in the wavelength of the illumination light, and detected by the CCD 52. The background light and ASE can be efficiently removed from the emitted light, and the SN ratio can be improved. Furthermore, since information on a plurality of positions to be measured can be detected in parallel, high-speed and high-sensitivity microscopic observation is possible even for a living biological sample.

(Fifth embodiment)
FIG. 9 is a block diagram showing a schematic configuration of the photodetection device according to the fifth embodiment of the present invention. This light detection device generates a wavelength swept light whose wavelength band is changed over time, and a plurality of wavelength swept light generation / irradiation means 10 for irradiating the measurement target 20 with the wavelength swept light, and a plurality of wavelength swept light generation / A plurality of optical amplifying means 30 provided corresponding to the irradiation means 10 and receiving and amplifying light obtained from the measurement object 20 by irradiation of the wavelength swept light by the corresponding wavelength sweep light generation / irradiation means 10, respectively. The light output from the optical amplifying means 30 is transmitted through each of the plurality of wavelength swept light filtering means 40 and the plurality of wavelength swept light filtering means 40 that continuously transmit the wavelength band of the transmission wavelength band. , Optical multiplexing means 70 for multiplexing, photoelectric conversion means 50 for converting the light combined by the optical multiplexing means 70 into an electrical signal, a plurality of wavelength swept light generating / irradiating means 10 and waves Configured to include a control unit 60 for controlling the sweeping light filtering means 40.

  Here, the control means 60 corresponds to the plurality of wavelength swept light filtering means 40 so as to transmit light in a band including the wavelength band of the wavelength swept light emitted from the corresponding wavelength swept light generation / irradiation means 10. Control is performed in synchronization with the time variation of the wavelength band in the wavelength sweep light generation / irradiation means 10. The optical multiplexing means 70 is constituted by, for example, an optical fiber type WDM (wavelength division multiplexing) coupler or a dichroic mirror. About another structure, it is the same as that of 1st Embodiment.

  With this configuration, the plurality of wavelength sweep generation / irradiation units 10 irradiate the detection position of the measurement target 20 with the wavelength sweep light obtained by sweeping the wavelength of the narrow band light in a wide band as illumination light. Here, each illumination light is swept in a different wavelength band. Light that is reflected, transmitted, or scattered by the measurement object 20 due to irradiation of illumination light having different wavelength bands to the measurement object 20 is input to the plurality of light amplifying means 30, and is amplified after being amplified. It is input to the sweep light filtering means 40. The wavelength sweep light filtering means 40 changes the transmission wavelength band in synchronization with the change in the wavelength band of the illumination light irradiated by the corresponding wavelength sweep light generation / irradiation means 10 under the control of the control means 60. Accordingly, the wavelength sweep light filtering means 40 transmits the signal light by the illumination light generated from the corresponding wavelength sweep light generation / irradiation means 10, and the background light, ASE, and other wavelength sweep generation / irradiation means 10 are transmitted. Removes the light emitted by the illumination light. Then, the output lights from the respective wavelength swept light filtering means 40 are multiplexed by the optical multiplexing means 70, converted into electric signals by the photoelectric conversion means 50, and processed.

  As described above, according to the present embodiment, in addition to the effects of the first embodiment, light detection can be performed for a plurality of wavelength bands at the same time. Even for applications that require detection of a spectral band that is wider than the wavelength band that can be swept by 10, this photodetection device can be used to detect light at high speed and with high sensitivity.

  In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible. For example, the wavelength swept light generating / irradiating means uses a wavelength tunable light source such as a wavelength tunable laser or a wavelength swept laser, but is not limited thereto. A white light source such as a xenon lamp may be used as the light source, and the light emitted from the white light source may be incident on a wavelength tunable optical filter to change the transmission wavelength of the optical filter to obtain wavelength swept light. .

DESCRIPTION OF SYMBOLS 10 Wavelength sweep light generation and irradiation means 11 Pr addition fluoride fiber type wavelength sweep laser 12 ISO
13 SMF
14 Collimator 15 Wavelength variable LD
16 ISO
17 SMF
DESCRIPTION OF SYMBOLS 18 Illuminating lens 20 Measurement object 21 Biological sample 22 Biological sample 30 Optical amplification means 31 Pr addition fluoride fiber type optical amplifier 32 Concentration lens 33 Scan mount 34 TF
35 SOA
36 Condensing lens 37 TF
38 ISO
39 ISO
40 wavelength swept optical filtering means 41 FFP-TF
42 BPF
50 Photoelectric conversion means 51 PD
52 CCD
60 control means 61 computer 63 driver 64 driver 65 driver 70 optical multiplexing means 81 driver 82 driver 83 electric amplifier 84 AD converter 85 display monitor 86 ISO
87 LD
88 WDM coupler 89 Optical filter 90 Pr-doped fluoride fiber 91 Optical filter 92 ISO
93 mount 94 housing 95 driver 101 signal light 102 background light

Claims (7)

A wavelength swept light generating / irradiating means for generating a wavelength swept light whose time band is changed, and irradiating the wavelength swept light to a measurement object;
Wavelength-swept light filtering means that receives light obtained from the measurement object by irradiation of the wavelength-swept light by the wavelength-swept light generation / irradiation means, and transmits the light by continuously changing the transmission wavelength band over time; ,
Photoelectric conversion means for converting the light transmitted through the wavelength swept light filtering means into an electrical signal;
The wavelength sweep time in the wavelength sweep light generation / irradiation means is transmitted so that the wavelength sweep light filtering means transmits light in a band including the wavelength band of the wavelength sweep light emitted from the wavelength sweep light generation / irradiation means. Control means for controlling in synchronization with the change;
A light detection apparatus comprising:   An optical detection device characterized in that an optical amplifying means for amplifying the light obtained from the measurement object is provided in a preceding stage of the wavelength swept light filtering means. A wavelength swept light generating / irradiating means for generating a wavelength swept light whose time band is changed, and irradiating the wavelength swept light to a measurement object;
Irradiation of the wavelength swept light by the wavelength swept light generation / irradiation means receives light from a plurality of different positions of the measurement object, and continuously changes the transmission wavelength band over time. A plurality of wavelength swept optical filtering means to be transmitted;
Photoelectric conversion means for converting the light transmitted through each of the plurality of wavelength swept light filtering means into an electrical signal;
A wavelength band in the wavelength swept light generating / irradiating means so that the plurality of wavelength swept light filtering means transmits light in a band including the wavelength band of the wavelength swept light emitted from the wavelength swept light generating / irradiating means. Control means for controlling each of them in synchronism with time changes,
A light detection apparatus comprising:   An optical detection apparatus comprising: a plurality of light amplifying means for amplifying the plurality of light obtained from the measurement objects, respectively, preceding each of the plurality of wavelength swept light filtering means. A plurality of wavelength swept light generating / irradiating means for generating a wavelength swept light whose time band is changed, and irradiating the wavelength swept light to a measurement object;
Each of the plurality of wavelength swept light generation / irradiation means is provided correspondingly, and receives the light obtained from the measurement object by irradiation of the wavelength swept light by the corresponding wavelength sweep light generation / irradiation means. A plurality of wavelength swept optical filtering means for continuously changing the transmission wavelength band with time, and transmitting the wavelength band;
Optical multiplexing means for multiplexing light transmitted through each of the plurality of wavelength swept light filtering means;
Photoelectric conversion means for converting the light combined by the optical combining means into an electrical signal;
The plurality of wavelength swept light filtering means transmit the corresponding wavelength swept light generation / irradiation so as to transmit light in a band including the wavelength band of the wavelength swept light emitted from the corresponding wavelength swept light generation / irradiation means. Control means for controlling each of them in synchronism with time variation of the wavelength band in the means;
A light detection apparatus comprising:   An optical detection apparatus comprising: a plurality of optical amplifying means for amplifying the light obtained from the measurement object, respectively, preceding each of the plurality of wavelength swept optical filtering means.   7. The photoelectric conversion unit according to claim 1, wherein the photoelectric conversion unit electrically integrates and outputs the light at a cycle equal to or longer than a sweep cycle of the wavelength sweep light generation / irradiation unit. The photodetection device according to any one of the above.

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