JP3315212B2 - Weak luminescence measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed timing weak light emission measuring device capable of outputting one-dimensional or two-dimensional position information.

[0002]

2. Description of the Related Art Conventionally, as a technique in such a field, for example, Japanese Patent Application Laid-Open No. 61-266942 is known. In this method, a light emission phenomenon in a sub-nanosecond region at a single photon level is measured by a single photon counting method.

In this conventional example, a light source for exciting a sample, a means for obtaining an excitation timing, a detecting means for obtaining detection timing and detection position information by detecting weak light emission from the sample, There is provided processing means for integrating the time difference information and the detected position information for each of a large number of excitations.

The detecting means has a photomultiplier tube including a photocathode, a microchannel plate (MCP), and an electron incident type semiconductor incident position detector (PSD). The detection timing is obtained from the potential change of the MCP, and the position information is obtained from the output of the PSD.

[0005]

However, in the above prior art, it is necessary to incorporate the semiconductor incident position detecting element inside an electron tube (photomultiplier tube). For this reason, the system tends to be expensive, and when a defect occurs in the semiconductor incident position detecting element, it becomes impossible to replace only this element.

Further, since the detection timing signal is obtained from an MCP different from the element for obtaining the position information, appropriate timing adjustment is required. Here, it is conceivable to determine the detection timing from the output of the semiconductor incident position detection element, but this may cause an increase in jitter in high-speed timing measurement.

[0007]

A weak light emission measuring apparatus according to the present invention has been made in order to solve the above-mentioned problems, and comprises a pulse light source for injecting an excitation light pulse into a sample that emits weak light when excited, Reference time pulse generation means for generating a reference time pulse synchronized with the incident timing of the light pulse,
By detecting the weak light emitted with a spatial spread at a single photon level, a detection time pulse synchronized with the detection timing and a position signal corresponding to the spatial position where the weak light is detected are output. Weak light emission detection means, time difference signal output means for outputting a time difference signal corresponding to the time difference between the reference time pulse and the timing of the detection time pulse, and the position signal and the time difference signal corresponding to each of a large number of excitations by the pulse light source. Data processing means for integrating the light emission, particularly the weak light emission detection means, a photocathode which emits photoelectrons in response to the weak light emission, and a multiplication means for multiplying the photoelectrons while holding the position information, And an image tube including a fluorescent screen that emits light by the incidence of multiplied electrons, and a metal back electrode deposited on the front surface of the fluorescent screen. Is output based on the potential change of the back electrode, the position signal is configured to be output by photoelectrically converting an optical image of the fluorescent screen.

[0008] Here, a spectroscopic means such as a prism for spatially dispersing the weak light emission may be provided in front of the light receiving surface of the weak light emission detection means.

[0009]

According to the present invention, the detection timing is obtained from the metal back electrode deposited on the fluorescent screen, which is equivalent to obtaining the detection timing from the anode for obtaining the position signal. In addition, a position signal can be obtained by a photoelectric conversion type imaging device provided outside the electron tube using the afterimage characteristic of the fluorescent screen.

[0010]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of the embodiment, and FIG. 2 is an exploded perspective view showing essential parts. The apparatus according to the embodiment includes an excitation optical system that excites the sample 1, a fluorescence optical system that spatially resolves weak light emission from the sample 1 according to the wavelength, a light detection system that detects the weak light emission, and outputs of these. It is composed of a processing system for processing signals.

First, as shown in FIG. 1, the excitation optical system has a pulse laser light source 21 for generating an excitation light pulse, and this output light is incident on the sample 1 via a half mirror 22 and a condenser lens 23. The fluorescent optical system has a condenser lens 31 for condensing weak light emission of the sample 1, and the collected detection light is incident on a spectroscope 32. The spectroscope 32 is incident on a slit plate 34 having a slit 33, is split by a prism 35, and is spatially resolved for each wavelength. That is, if the detection light includes light of wavelengths λ ₁ and λ ₂ , position information is provided for each wavelength as shown in FIG. ND not shown
The detection light is reduced to a single photon level by a filter or the like.

The light detection system comprises an image tube 4 called, for example, an image intensifier tube (II tube). The image tube 4 has a photoelectric surface 41 formed on a light receiving surface.
A microchannel plate 42 for multiplying the emitted photoelectrons, and a fluorescent surface 43 formed on an output surface.
On the fluorescent surface 43, a metal back electrode 44 is deposited. The metal back electrode 44 is a thin metal film formed by vapor deposition or the like, and prevents light on the fluorescent screen 43 from being fed back to the microchannel plate 42.

According to such an image tube 4, as shown in FIG. 2, the wavelength lambda ₁ incident on the photocathode 41, lambda ₂ of photoelectrons e _1, e ₂ in response to light emitted, the micro-channel plate The light is increased to a multiplication factor m (approximately 10 ⁶ ) times 42 and is incident on the fluorescent screen 43. Here, the photocathode 41,
The bias voltages E ₁ , E ₂ , E ₂ are applied to the metal back electrode 44 on the microchannel plate 42 and the fluorescent screen 43.
_3, and an electron lens system (not shown) is also provided.

According to this configuration, the metal back electrode 44
Since the potential changes at the timing when the multiplied electrons are incident on the metal back electrode 44, the potential change of the metal back electrode 44 equivalent to the anode can be used as the detection time timing. The fluorescent screen 43 emits light in synchronization with this timing, and this is imaged by the image sensor 5. Here, since the image sensor 5 has a position resolution in the direction of spatial resolution for each wavelength by the spectroscope 32, the incident position information can be output as an electric signal.

The processing system is roughly classified into a timing processing system, a processing system for incident position information, and a processing system for integrating these data. First, the timing processing system has a photodiode 61, and the output, that is, a reference time pulse synchronized with the incident timing of the excitation pulse light, is passed through a first constant fraction discriminator (CFD ₁ ) 62 to a time-voltage converter (CFD ₁ ). TAC) 63 is input to the start terminal. on the other hand,
The change in the potential of the metal back electrode 44 is
Is input to the stop terminal of the time-to-voltage converter 66 via the constant fraction discriminator (CDF ₂ ) 65. The time-voltage converter 66 obtains a time difference between the start and the stop, and outputs it as a time difference signal.

On the other hand, the position information processing system comprises a position detecting circuit 71.
And outputs the position information signal by calculating the output of the image sensor 5. Here, the timing signal generation circuit 8 obtains a signal for timing synchronization based on the output of the second discriminator 65 based on the detection time timing, and outputs this signal to A
D converters (ADC ₁ , ADC ₂ ) 72 and 66 are provided. In accordance with this, the AD converter 66 digitizes the time difference signal from the time-voltage converter 63 and supplies it to the memory 91, and the AD converter 72 digitizes the position information signal from the position detection circuit 71 and supplies it to the memory 91.

A memory 91 as an integrated processing system includes a CPU
According to the control of 92, the position information signal and the time difference signal for each excitation are integrated. That is, the excitation of the sample 1 by the pulse laser light source 21 is repeated many times, and the position information signal and the time difference signal obtained for each excitation are stored in the memory 91 as a pair.

As a result, the weak light emission is observed by the single electron counting method. In this observation, since the one-dimensional position resolution is performed according to the wavelength, the weak light emission measurement for each wavelength is realized. Then, it is displayed on a CRT or the like as necessary.

According to the above-described embodiment, it is possible to obtain a time-resolved characteristic of 50 ps or less, similar to the case where the MCP-PMT is used. Further, since the position information is obtained from the light emission of the fluorescent screen 43, the afterglow characteristics of the phosphor can be used, and accurate position information can be obtained without requiring an accurate timing signal. That is, when the position information is extracted not by light but by an electric signal as in the related art, appropriate timing is required. Furthermore, unlike the case where the MCP-PMT is used, in the present invention, position information (wavelength in the embodiment) can be obtained at the same time.

[0021]

As described above, in the weak light emission measuring apparatus of the present invention, the detection timing is obtained from the metal back electrode deposited on the phosphor screen, so that the detection timing is obtained from the anode for obtaining the position signal. Is equivalent to In addition, a position signal can be obtained by a photoelectric conversion type imaging device provided outside the electron tube using the afterimage characteristic of the fluorescent screen. As a result, a high-speed timing signal having excellent time-resolved characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a weak light emission measuring device according to an embodiment.

FIG. 2 is a perspective view of a main part of the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... sample, 21 ... pulse laser light source, 32 ... spectroscope, 4
... image tube, 41 ... photoelectric surface, 42 ... microchannel plate, 43 ... fluorescent surface, 44 ... metal back electrode,
5 image sensor, 66 time-voltage converter, 71 position detection circuit, 8 timing signal generation circuit, 92 CP
U.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-266942 (JP, A) JP-A-54-2789 (JP, A) JP-A-61-148352 (JP, A) JP-A 64-64 57132 (JP, A) JP-A-5-188001 (JP, A) JP-A-59-58745 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/62-21 / 74 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A pulse light source for injecting an excitation light pulse into a sample that is excited to emit weak light, a reference time pulse generating means for generating a reference time pulse synchronized with the incident timing of the excitation light pulse, and a spatial expanse. Detecting at a single photon level the weak light emission incident thereon with a weak light emission detection that outputs a detection time pulse synchronized with the detection timing and a position signal corresponding to the detected spatial position of the weak light emission Means, time difference signal output means for outputting a time difference signal corresponding to the time difference between the timing of the reference time pulse and the detection time pulse, and the position signal and the time difference signal corresponding to each of a number of excitations by the pulse light source. Data processing means for causing the light emission to be integrated, wherein the weak light emission detecting means comprises: a photoelectric element which emits photoelectrons in response to the weak light emission A surface, a multiplying means for multiplying the photoelectrons while retaining the position information, a fluorescent surface emitting light upon incidence of the multiplied electrons, and a metal back electrode deposited on the front surface of the fluorescent surface. An image tube, wherein the detection time pulse is output based on a potential change of the metal back electrode, and the position signal is configured to be output by photoelectrically converting an optical image on the fluorescent screen. Characteristic weak light emission measuring device. 2. The weak light emission measuring apparatus according to claim 1, further comprising a spectral means for spatially separating the weak light emission in front of a light receiving surface of the weak light emission detecting means.