JP2002022660A - Multi wavelength fluorescent measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi wavelength fluorescent measuring apparatus which can obtain fluorescent signals for every wavelength in real time at the same time without decreasing a signal level and can obtain true spectral wavelength characteristics. SOLUTION: There are set a laser oscillator 1 for irradiating a short pulse output 2 via an emission optical system 3 to an ocean surface, and a light- receiving means comprising a plurality of filters 5a-5d for receiving a fluorescence 4 emitted from a suspended matter of the ocean surface, a plurality of light-receiving optical systems 6a-6d and a plurality of photoelectric multipliers 7a-7b. Outputs 7aa-7dd of the photoelectric multipliers 7a-7d are processed by a signal processor 8 controlled by a data controller 35, and the output signal is displayed by a data output unit 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring fluorescence emission, and more particularly to an apparatus for measuring fluorescence from a floating substance on the ocean surface which emits light by laser excitation.

[0002]

2. Description of the Related Art Attempts to measure positional information or component information of oil spilled on the ocean surface by a so-called fluorescent lidar have been continued since the 1970s (RMMe).
asures, Laser Remote Sensi
ng Fundamentals and Appli
sessions, John Wileys and S
ons, p424). This is, for example, by irradiating a laser from the aircraft to the ocean surface to excite the floating oil spill, emit the fluorescence unique to the spilled oil, detect this with a photomultiplier tube, and measure the light emission distribution. It is intended to acquire positional information such as an oil drift route and its speed, and acquire oil component information by grasping the wavelength of fluorescence.

In the measurement of the wavelength characteristic of fluorescence, the fluorescence is received by a telescope, and various filters are sequentially inserted into an optical path leading to a photomultiplier tube to measure a change in a detected electrical signal. The change in the detection signal with respect to the transmission wavelength range of the inserted filter indicates the wavelength characteristic of the fluorescence. In this way, the operation of recovering suspended matters is effectively performed, the degree of completion of the recovery operation is evaluated, and the temporal deterioration of the oil spill is to be investigated.

[0004] Similarly, an attempt has been made to specify the concentration and type of the plankton by measuring the fluorescence of the ocean surface and the sea using a fluorescence lidar (Japanese Patent Laid-Open No. 4-69).
546). Phytoplankton, which absorbs carbon dioxide released on the earth by carbon assimilation,
It is said that it is greatly contributing to the reduction of carbon oxides, and understanding its concentration distribution is important as a measure against global warming.

However, since these fluorescent lidars detect the fluorescence at one point on the ocean surface irradiated with the laser beam with the photomultiplier, only the characteristics of the object at the one point can be obtained.

Therefore, in order to determine the two-dimensional distribution of oil spills that have spread over the ocean, it is necessary to scan laser light two-dimensionally and to form a two-dimensional image with a computer.

[0007]

The above uses and objects are all important issues for protecting the global environment.
One of the reasons for not yet reaching the practical stage is that when trying to grasp the wavelength characteristics of fluorescence, it is necessary to mechanically replace filters having different transmission wavelength ranges.

That is, the laser that excites fluorescence is a short-pulse high-power laser with a pulse width of several nanoseconds, and the duration of fluorescence of oil spilled by this irradiation is less than 100 nanoseconds. This is because it is impossible to determine the wavelength characteristics of the fluorescent light by performing the measurement.

Therefore, when measuring the fluorescence wavelength characteristic by inserting the filter into the light receiving path while sequentially replacing the n filters,
It is impossible to detect a fluorescence signal spectrally separated for each wavelength in real time, and it takes at least n times the filter replacement time as the measurement time at a certain target point.
During this time, the irradiation position of the laser beam on the sample is required to be fixed. This is because if the fluorescence at the same location is not spectrally separated, the true measurement is not performed when the characteristics on the sample have a distribution.

On the other hand, when a fluorescent lidar device is mounted on an aircraft to irradiate the ocean surface, it is not possible to keep the positional relationship between the aircraft and the offshore sample constant over a measurement time that is n times as long as one filter exchange time. Can not. As shown in FIG. 4, the incident fluorescent light 4 to be received is shaped by a light receiving optical system 6 and divided into a plurality of beams by a beam splitter 12. Different filters 5a, 5b, 5c, 5d
Is inserted, and a desired spectral fluorescence characteristic is measured by the photodetector 7.

However, in this case, the division of the signal light and the reduction of the signal level due to the loss in the beam splitter used for the division may be fatal, and cannot be said to be a preferable method.

Accordingly, an object of the present invention is to provide a multi-wavelength fluorescence measuring apparatus capable of simultaneously acquiring a fluorescence signal for each wavelength in real time without reducing the signal level and acquiring a true spectral wavelength characteristic. To provide.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises a set of laser light irradiation means including a laser light source and an emission optical system for guiding the laser light to the ocean surface. Light receiving optics including filter to receive fluorescence from suspended matter such as oil spills above, photomultiplier tube, CCD
It is configured such that a plurality of light receiving systems including photodetectors such as cameras are arranged.

That is, in each of the plurality of light receiving systems, a filter having a different transmission wavelength region is inserted, so that each light receiving system measures the fluorescence output in a certain wavelength region and integrates the outputs to measure the fluorescence wavelength characteristics. Can be grasped in real time.

[0015]

FIG. 1 shows a first embodiment of the present invention. For example, a short pulse output 2 is emitted from a laser oscillator 1 such as a third harmonic (wavelength: 355 nm) of an Nd: YAG laser. The marine surface is irradiated via the optical system 3. Only a part of the fluorescent light 4 emitted from floating substances such as oil spills on the ocean surface by this irradiation is transmitted through the transmission wavelength range of the filter 5a and condensed via the light receiving optical system 6a, and is collected by the photomultiplier tube 7a. , And the electrical output 7aa is processed by the signal processing device 8 to measure the fluorescence pulse time waveform 9a of the wavelength range on the screen of the data output device 34 such as an oscilloscope.

FIG. 1 shows four light receiving systems, and similarly, a fluorescent pulse time waveform 9 relating to the transmission wavelength region of the filter 5b from the electric output 7bb of the photomultiplier tube 7b.
b, a fluorescence pulse time waveform 9c relating to the transmission wavelength range of the filter 5c and a fluorescence pulse time waveform 9d relating to the transmission wavelength range of the filter 5d are obtained. Then, if an instruction is given from the controller 35 that controls the operation of the signal processing device 8, these four fluorescent pulse time waveforms can be simultaneously drawn.

Further, by instructing the controller 35 to the signal processing device 8, it is given a time axis of each fluorescent pulses, fluorescence wavelength characteristic at a time t ₁ 10
Can be drawn on an output device 34 such as an oscilloscope or a printer.

As described above, according to the present invention, it is possible to obtain the fluorescence wavelength characteristics in real time without replacing the filter.

In the above-mentioned measurement, only the fluorescence information of one point on the ocean irradiated with the laser light is obtained. Need to do a scan. Location information 11
And the respective fluorescent pulse time waveforms 9 are made to correspond to each other by the signal processing device 8, it is possible to create a two-dimensional fluorescent image for each wavelength range.

As described above, according to the present invention, one point of fluorescence information is thus obtained in real time,
Thus, a two-dimensional fluorescent image could be created by scanning with the laser.

However, if the laser output is large and a fluorescent signal can be obtained even when the laser beam is expanded to some extent on the ocean surface, an image intensifier may be added instead of a photomultiplier as a photodetector, and an image may be added. If an imaging device such as an enhanced CCD camera is used, a two-dimensional fluorescence spectroscopic image can be obtained immediately.

FIG. 2 shows an embodiment of the present invention, in which a short pulse output from the laser oscillator 1 irradiates an area on the ocean surface via an emission optical system 23. By this irradiation, only a part of the incident fluorescent light 24 having a spread generated from a floating substance on the ocean surface is transmitted through the transmission wavelength range of the filter 25a, and is transmitted through the light receiving optical system 26a to the photoelectric surface of the image intensifier 28. An image is formed on the fluorescent screen 30, an image is formed on the fluorescent screen 30, and the image reaches the CCD camera 31. As a result, a fluorescent image having a two-dimensional spread related to the transmission wavelength range of the filter 25a can be measured by the CCD camera 31a.

FIG. 2 shows four light receiving systems. Similarly, fluorescent images relating to the transmission wavelength range of the filters 25b, 25c and 25d are similarly captured by the CCD cameras 31b, 31c and 3c.
It can be measured at 1d.

Therefore, in the case of the embodiment of FIG.
Four images 32a, 32b, 32 captured by the D camera
c, 32d are four image display devices 33a, 33b, 3
Although displayed on 3c and 33d, the fluorescence emitted by the suspended matter is spectrally separated in real time into four different wavelength ranges. In this case, since the light receiving system does not have a high-speed response at the nanosecond level, a fluorescent pulse waveform as in a photomultiplier tube cannot be obtained, but an image of a CCD camera is formed as an electric signal proportional to the integral value of the pulse waveform. ing.

The fluorescent image 32 is obtained from the signal of the CCD camera.
a, 32b, 32c, and 32d can be taken out and processed by the signal processing unit 8 by giving an instruction from the data controller 35 to obtain the fluorescence intensity from the wavelength-specific signal level at a certain point in the fluorescence image at a certain time. The wavelength characteristic 10 can be extracted and displayed on the data output device 34. Generally, a fluorescent characteristic unique to the type of oil is known, and by referring to this, the component of the spilled oil can be estimated.

FIG. 2 shows an image intensifier and a CC as devices for imaging.
An example in which four D cameras were used was shown. In order to reduce the cost of the apparatus and simplify the level adjustment of the elements of each channel, it is possible to use only one image intensifier and one CCD camera.

FIG. 3 shows an embodiment of the present invention, in which a short pulse output 22 from the laser oscillator 1 irradiates an area on the ocean surface via an emission optical system 23. Only a part of the incident fluorescent light 24 that has spread from the floating material on the ocean surface due to this irradiation and that transmits through the transmission wavelength range of the filter 26a passes through the light receiving optical system 26a and is turned back to the mirror 2.
Change the position by 7 and use the image intensifier 28
The image is intensified by forming an image on a part of the photoelectric surface 29, and the image is formed on the fluorescent surface 30 so as to reach a part of the effective area of the CCD camera 31. This allows the filter 25a
A fluorescent image having a two-dimensional spread related to the transmission wavelength range can be measured by a part of the effective area of the CCD camera 31.

FIG. 3 shows four light receiving systems. In the same manner, the fluorescent images relating to the filters 25b, 25c and 25d can be measured on the remaining effective portion of the CCD camera.

Therefore, in the case of the embodiment shown in FIG. 3, four images on one screen captured by one CCD camera are:
Fluorescence emitted by the purified substance is spectrally separated in real time into four different wavelength ranges. Also in this case, similarly to the second embodiment of FIG. 2, an image is formed using an integral value of a pulse waveform proportional to the amount of fluorescence in each wavelength region as an electric signal.

In this way, the four fluorescent images 32a, 3a,
2b, 32c, and 32d can be displayed. Also,
As in the case of the embodiment of FIG. 2, the signal processing device 8 performs the processing by designating the wavelength characteristic 10 of the fluorescence from the signal level by wavelength at a specified point of the fluorescent image at a certain time by specifying the data via the data controller 35. The output can also be output to the output device 34, which is effective for estimating the component of the spilled oil.

When selecting the transmission wavelength of the filter, it is also effective to grasp the fluorescence characteristics of the target and to select a transmission wavelength range convenient for standardization and calibration of the measurement system. That is,
Third excitation of Nd: YAG laser as excitation light for fluorescence emission
When a higher wavelength of 356 nm is used, a 407 mm spectrum may be received as Raman scattering light of water. If the level of the received signal of this spectrum is verified by the present apparatus based on various conditions of seawater and the level of excitation light, it is effective for level adjustment of the apparatus, level adjustment between channels, gate timing adjustment, and the like.

In the configuration shown in FIGS. 2 and 3 using a CCD camera, a fluorescence spectroscopic image emerges on the sea surface, coast, rocky reef, building, or the like as a background, so that the image can be analyzed and analyzed immediately. It is very effective as a guideline for recovering oil spills that require urgency.

In each of the embodiments shown in FIGS. 1, 2 and 3, the number of the light receiving systems is four. However, it is needless to say that the number of the light receiving systems can be increased or decreased as needed. When it is sufficient to grasp the fluorescence intensities in certain two wavelength ranges, it is sufficient to capture two images with a CCD camera, and the cost of the apparatus can be reduced. Conversely, if it is desired to increase the wavelength resolution, more light receiving systems will be arranged.

In the embodiments shown in FIGS. 2 and 3, the level of the fluorescent light to be received is increased by using an image intensifier and converted into an electric signal. This is because a case in which weak fluorescence is measured is assumed. If the measuring device is mounted on a ship and the level of fluorescence from the spilled oil can be ensured, the image intensifier can be omitted and the measurement can be performed only with a CCD camera.
In particular, if an electronically cooled “cooled CCD camera” is used, an image having low noise and a large dynamic range can be obtained. In realizing the idea of the present invention, there are several other devices for the photodetector.

That is, there is a photodiode or an avalanche diode as a solid-state photodetector relating to the point corresponding to the photomultiplier tube in FIG.
There is also a two-dimensional photodiode array corresponding to a D camera. 2 and 3, the CCD camera is simply represented as a CCD camera. In addition to the above-mentioned cooled CCD camera, there is a back-illuminated CCD camera and the like. To select.

[0036]

According to the present invention, it becomes possible to accurately and in real time perform fluorescence spectroscopic image measurement, which has been inefficient and inaccurate due to the work of replacing the filter in the past. As a result, environmental pollution countermeasures against spilled oil can be implemented quickly, efficiently, and strategically.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a block diagram showing a main part configuration, and FIG.

FIGS. 2A and 2B show a second embodiment of the present invention, in which FIG. 2A is a block diagram showing a main part configuration, and FIG.

FIGS. 3A and 3B show a third embodiment of the present invention, in which FIG. 3A is a block diagram showing a main part configuration, and FIG.

FIG. 4 is a block diagram of a conventional embodiment.

[Explanation of symbols]

 Reference Signs List 1 laser oscillator 2 short pulse output 3 emission optical system 4 fluorescence from floating matter 5a, 5b, 5c, 5d filter 6a, 6b, 6c, 6d light receiving optical system 7a, 7b, 7c, 7d photomultiplier tube 8 signal processing device 9a, 9b, 9c, 9d Fluorescence pulse time waveform 10 Fluorescence wavelength characteristic 11 Scan position information 12 Beam splitter 22 Short pulse output 23 Emission optical system 24 Fluorescence from suspended matter 26a, 26b, 26c, 26d filter 26 Receiving optical system 27 folding mirror 28 image intensifier 29 image intensifier photoelectric surface 30 image intensifier fluorescent surface 31 CCD camera 32 fluorescent image 33 image display device 34 data output device 35 data controller

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G020 AA04 CB23 CB43 CC26 CC47 CD23 CD24 CD52 2G043 AA03 AA04 BA14 BA15 CA03 EA01 EA03 FA01 FA05 FA06 GA02 GA04 GA21 GB01 GB21 HA01 HA02 JA03 KA02 KA05 KA08 KA09 LA02 NA03

Claims (6)

[Claims] 1. A laser beam irradiation means comprising a laser light source and an emission optical system, a plurality of filters each having a different transmission wavelength range, a plurality of light receiving optical systems, and a plurality of light detectors. And a signal processing device for forming fluorescence spectral characteristics from a plurality of received signals from the plurality of photodetectors. 2. The method according to claim 1, wherein the scanning device scans a laser light source and supplies the plurality of received signals and the scan state signal to the signal processing device to display a spectrally-fluorescent image on a display device. The multi-wavelength fluorescence measurement device according to claim 1. 3. A laser light irradiation means comprising a laser light source and an emission optical system, a plurality of filters each having a different transmission wavelength range, a plurality of light receiving optical systems, several image intensifiers and a plurality of image intensifiers. A light receiving means comprising a CCD camera and a signal processing device supplying received signals from the plurality of CCD cameras to a plurality of or a single display device to display the separated fluorescent images. And a multi-wavelength fluorescence measuring device capable of forming fluorescence spectral characteristics. 4. A method according to claim 1, further comprising the step of arranging folding mirrors in said plurality of light receiving optical systems to convert an incident light into an optical path, guide the light to a single image intensifier, and take an image with a CCD camera. 4. The multi-wavelength fluorescence measurement device according to claim 3, wherein the multi-wavelength fluorescence measurement device is capable of displaying a separated fluorescence image on a single display device and / or being capable of forming fluorescence spectral characteristics. 5. The multi-wavelength fluorescence measuring apparatus according to claim 1, wherein said plurality of light receiving optical systems are arranged concentrically around said laser beam irradiation means. 6. A plurality of filters each having a different transmission wavelength range, wherein one of the transmission ranges matches the Raman scattering spectrum of water.
The multi-wavelength fluorescence measurement device according to any one of the above.