JPH05346350A - Device for obtaining space and time characteristics of weak radiation light from spacimen - Google Patents

Abstract

PURPOSE: To capture space and time characteristics of weak tested radiation light with high accuracy by introducing an adder and subtracter to a device, simplifying the device and suppressing noise generation. CONSTITUTION: Information holding signal impressed in time/amplitude converters 11 and 12 is obtained from a delay line 6 i.e., an anode terminal of photomultiplier 3. In this case, an adder 19 outputs a signal proportional to the instant delay for discharging of photon from the specimen with respect to drive pulses of a light radiator 1. A subtracter 20 outputs signals proportional to the spacial position of a luminescence source. By providing common channel of the devices, the circuit constitution is simplified. As the signal output from the anode of the photomultiplier 3 (different from the signal output from a small channel plate electrode) has a sufficient amplitude to enable detecting highly reliably, time characteristic capturing accuracy of radiation light is raised. Since the time/amplitude converter 11 and 12 detects the signal in a short time, noise can be reduced by synchronizing the two devices with a signal generator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optics and electronics, and more particularly to an apparatus for measuring weak photo-radiation properties, radiation exposure times in picoseconds and nanoseconds.

The present invention is applicable to spectroscopy, that is, in the fields of medicine, microbiology, microelectronics, geology, etc.
It can be used to study processes such as photoexcitation energy relaxation in molecules and crystals, and can obtain information about the excited electronic state lifetime of molecules in solution, carrier relaxation rate in crystals, photochemical metamorphic channels, and the like. Also, with a sufficiently powerful radiation source, and its associated optics, equipment aimed at remote object investigations, such as spacecraft size and position measurements or surveys of raised giant objects. Can be the basis for realizing.

[0003]

2. Description of the Related Art A device for obtaining temporal characteristics of weak light radiation is "Kvantovaya Electronica".
Elektronika) Moscow 1987 Vol. 14, No. 6, pp. 1303-130
It is proposed in "Photon calculated from fluorescence of 10 ^-9 seconds or less by a laser beam" by VF Kamalov et al. On page 8.

This device comprises a pulsed laser emitter, a photomultiplier, a photodiode, and a time-amplitude converter, the holder of which holds the subject, the output of which is connected to a multichannel analyzer. Which are all arranged in the laser beam path. A variable wavelength monochromator is provided in front of the photocathode of the photoelectric multiplier. The starting input of the time-amplitude converter is connected to the output of the photodiode, and its stopping input is connected to the anode of the photoelectric multiplier via the discriminator. The photodiode and the subject are irradiated with a laser beam to cause fluorescent discharge. Radiation emitted by the subject having a particular wavelength, as indicated by the monochromator, is converted by a photomultiplier into an electrical signal. The time-amplitude converter raises the voltage in proportion to the delay time (determined by the photodiode pulse) when the photon is emitted from the subject and when the photon is emitted. The multi-channel analyzer stores the measurement result in the channel corresponding to the measured delay time. Once a sufficient number of time-amplitude converter outputs have been stored, the multi-channel analyzer will provide a single fixed wavelength for the amplitude and amplitude of the radiation under investigation.
It emits a signal that represents the time characteristic.

A device for capturing the spatial characteristics of a weak luminescence source is "Review of Scientific Instrument".
s) 1987 Vol. 58, No. 12, pp. 2298-2305, by M. Lampton et al.
Delay line anodes for plate spectrometers ”.

The device comprises a photodetector with a microchannel plate and a delay line anode system in which the start and stop inputs of the time meter are connected via a discriminator. When radiation is emitted from the subject, electric charge is locally generated from a specific point on the photocathode of the detector, and the charge generation point of the photocathode of the delay line and the luminescence point of the subject are coordinately matched. Applied to the point. The local charge generated in the delay line becomes a source of two electric pulses that travel toward both ends of the delay line. The time meter starts and stops with these pulses. The arrival time of the electrical pulse towards both ends of the delay line is measured to determine the spatial position of the photocathode that the photon emitted from the subject reaches. By storing the measurement result, the spatial distribution information of the light intensity can be obtained.

Each of the above devices can obtain only one characteristic (spatial characteristic or temporal characteristic) of weak emitted light. However, to investigate an object that results from luminescence altering its spatial position over time, or when luminescence is temporally separated and results from the stacking of several components, the And temporal characteristics need to be measured simultaneously.

Therefore, for example, an important duty in spectroscopy is to separate the Raman scattering spectrum, fluorescence spectrum and phosphorescence spectrum emitted by molecules having different delay times after pulse excitation.

Further, the fluorescence spectrum changes with time upon reconstruction or energy relaxation processing. This problem cannot be solved by alternately measuring the spatial characteristics and then the temporal characteristics.

Therefore, an apparatus for determining the weak light emission characteristic of an object is described in W. G. McMullan
It is proposed in "Simultaneous time information of 10 ^-9 seconds or less and two-dimensional information from image photomultiplier tube" by others.

This device provides the spatial and temporal information of the radiation to be tested at the same time. It consists of a photomultiplier with a microchannel plate and a two-dimensional resistive anode which is essentially a delay line. Is becoming Two pairs of terminals are arranged at right angles to each other at both ends of the anode, and are connected to a position selection computer connected to a personal computer. This device is also connected to a second personal computer via a pulsed laser radiator that irradiates an object placed in the holder, an avalanche photodiode that diverts part of the pulsed laser radiation, and an amplitude pulse analyzer. Equipped with a time / amplitude converter.

The signal applied to the starting input of the time-amplitude converter is derived from the RC circuit connected to the output electrode of one of the microchannel plates of the photomultiplier. The stop input of this converter is connected via an amplifier and a discriminator to the output of an avalanche photodiode, which produces electrical pulses in synchronism with the pulses of the laser emitter. The minute channel plate pulse has a positive polarity and a very low amplitude, so it
An amplifier, an inverter, and a discriminator are inserted between the stop input end of the amplitude converter.

The locating computer determines the two-dimensional spatial coordinates of the halo source, or puts the instrument into a spectroscopic mode if the test radiation is scattered linearly over the wavelength of the photocathode of the photomultiplier. Then, the wavelength information is captured using the measurement result along one axis.

The personal computer stores and processes these measurements and produces a spectrum of the luminescence under test, ie a spectrum which represents the spatial position of the luminescence source.

The time-amplitude converter generates a voltage proportional to the time interval from the time of irradiation of the object to the time of appearance of an electric signal to the photoelectric multiplier (corresponding to the moment when the object emits photons). To do. This voltage is digitally converted by the amplitude pulse analyzer, enters the second personal computer, and is displayed as an amplitude / time characteristic.

The drawback of the device is that it has two measuring channels.
In order to separately provide (one that uses the signal from the photoelectric multiplier that obtains the spatial characteristics of the emitted light and one that uses the signal from the minute channel plate electrodes that are configured to obtain the time characteristics), the device The point is that it gets complicated. Moreover, since these channels are not synchronized, it is easy to detect a noise pulse (generated from the anode of the photoelectric multiplier) in the spatial position measurement channel. These nozzle pulses may be confused with the desired signals, and display errors may occur.

Further, in the above-mentioned apparatus, the pulse emitted from the electrode of the minute channel plate of the photoelectric multiplier is timed ("Time").
Since it is used as a timing signal for a channel, it lacks the accuracy of capturing the temporal characteristics of synchrotron radiation. Since the amplitude of this pulse signal is small and needs to be amplified at a later date, it is difficult to detect a signal having time information against a noise background.

Further, since the timing signal generating terminal of the minute channel has a potential opposite to the case of the device (that is, the anode of the photoelectric multiplier), maintenance becomes complicated.

[0019]

SUMMARY OF THE INVENTION The present invention is a device for capturing the spatial and temporal characteristics of weak synchrotron radiation emitted from an object, which uses a common measurement channel to measure the spatial and temporal characteristics of the synchrotron radiation. Along with capturing time information, the signal output from the anode of the photoelectric multiplier equipped as a delay line is used as an information holding signal to simplify the structure and eliminate the detection of noise signals to improve measurement accuracy. The purpose is to provide the device.

[0020]

[Means for Solving the Problems] The above-mentioned problem is an apparatus for evaluating the space and time characteristics of weak radiated light emitted from an object, which irradiates a holder holding a subject and the subject, Pulsed light emitter that captures the weak emitted light emitted from the device, photoelectric multiplier equipped with a delay line-shaped anode that converts the weak emitted light emitted from the subject into an electrical signal, an electrical pulse synchronized with the pulse of the optical emitter Generating means,
The first input terminal includes a time / amplitude exchanger connected to both output terminals of the electric pulse generator, and a data storage processing device, and the adder circuit, the subtractor circuit, and the first input terminal of the electric pulse generator. The second time-amplitude converter is connected to the output terminal, and the second input terminal is connected to one end of the delay line. The second input terminal of the first time-amplitude converter has both ends of the adding circuit. An input terminal and both input terminals of the subtraction circuit are connected, and an output terminal of the adder circuit and an output terminal of the subtraction circuit are connected to both input terminals of the data storage processing device.

[0021]

By introducing a second time-amplitude converter, and an adder and a subtracter connected to the output terminals of the first and second converters into the device of the present invention, the space-time of the radiated light under test is introduced. You can set up a common measurement channel that captures the information.

In this measuring channel, the information-carrying signal applied to the time-amplitude converter is obtained from the delay line, ie from the end of the anode of the photoelectric multiplier. In this case, the adder outputs a signal in response to the driving pulse of the light emitter, which is proportional to the instantaneous delay of the emission of photons from the subject, and the subtractor outputs the signal as described in detail below. It outputs a signal proportional to the spatial position of. The circuit configuration can be simplified by providing a common measurement channel in the device.

Also according to the invention, firstly, the signal emitted from the anode of the photomultiplier is sufficient to allow reliable detection (unlike the signal emitted from the microchannel plate electrodes). Since it has a large amplitude, it is possible to improve the accuracy of capturing the time characteristic of the emitted light. Secondly, since the time / amplitude converter detects a signal in a short period of time, noise can be reduced by synchronizing the two time / amplitude converters with the signal generator. Furthermore, by synchronizing the transducers, the spatial and temporal coordinate measurements can be fixed at one event, the detection of emitted photons.

[0024]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

Space of weak synchrotron radiation emitted from an object
A device with time characteristics is formed by a pulsed light emitter, such as a laser pulse emitter (1), a photodiode (2) and a test radiation, and a photocathode (4), eg a microchannel plate. It comprises a multiplication system (5) and a photoelectric multiplier (3) including an anode in the form of a delay line (6).

The ends (7) and (8) of the delay line (6) are connected to the stop input terminals (9) and (10) of the time / amplitude converters (11) and (12), respectively. Start input terminal (13) of time / amplitude converter (11) (12)
Each of (14) is connected to the output terminal of the photodiode (2).

In the beam propagation path of the laser radiator (1),
This beam consists of two sub-beams, one directed to the photodiode (2) and a holder (16) (in the form of a cell if the subject is a solution, or in the form of a clamp if the subject is a solid). Divided into those facing the subject attached to,
A semi-transparent mirror (15) or similar means is provided. Therefore, the radiation excited in the subject by the laser beam reaches the photocathode (4) of the photomultiplier (3).

To determine the spatial properties of the subject luminescence, a polychromator (17) and other diffuser elements can be provided in front of the photocathode (4). The lens (18) is used to capture an image of the subject present, either the charging cathode (4) or the polychromator (1).
It serves as a display on the input slit of 7).

The generator of the electric pulse synchronized with the pulse of the laser radiator (1) can be composed of a photoelectric multiplier and other photoelectric devices in addition to the photodiode (2). Similarly, instead of the laser pulse emitter (1), a continuous air-light discharge tube with a flash air discharge lamp or a light modulator can be used.

The present invention further comprises an adding circuit (19) and a subtracting circuit (20), the input terminals of both circuits being connected to the output terminals of the time / amplitude converters (11) (12). .. In addition, the output terminals of both circuits are PC-shaped
It is connected to the input ends (21) and (22) of the processing device (23).

Next, the operation of the apparatus of the present invention will be described. The subject is placed in the holder (16). Laser radiator (1)
Is turned on to generate a short-term (eg, picosecond unit) light pulse.

A part of the pulsed radiation of the laser is reflected by the semitransparent mirror (15) and goes to the photodiode (2). The photodiode generates an electric pulse in synchronization with the laser pulse. These electrical pulses are applied to the starting inputs (13) (14) of the time-amplitude converters (11) (12) and trigger this converter.

The rest of the laser radiation passes through the mirror (15) and illuminates the subject, becoming a light pulse radiation whose characteristics are to be determined. The photoelectric multiplier (3) that detects this radiation is
Operates in single-electron mode. The photomultiplier (3) operates in single electron mode. The photoelectrons emitted by the photocathode (4) of the photomultiplier (3) are, when passing through the multiplication system (5), the coordinates of the point on the photocathode (4) where the photoelectrons are emitted and the photon of the radiation under investigation. Coordinates of the point on the subject where the
Alternatively, if a polychromator (17) is worn, it will generate a charge that reaches a particular point on the delay line (6) having coordinates corresponding to the wavelength of the photons emitted by the subject.

After the charge of the delay line (6) is divided into two,
Propagating towards the ends (7) (8) of the delay line, it issues a signal to stop the time-amplitude exchangers (11) (12) via their respective stop inputs (9) (10). The time / amplitude converter (11) (12)
Each is a device that outputs a voltage proportional to the time interval between the signals arriving at its start and stop inputs.

Therefore, the output voltage U ₁ of the time-amplitude converter (11) is proportional to the time interval Δt + X / V, while the output voltage U ₂ of the time-amplitude converter (12) is the time interval Δ. t +
Proportional to (1-X) / V. Here, Δt is the time interval from the pulse generation of the photodiode (2) to the charge arrival at the delay line (6), l is the length of the delay line (6), and V is
The charge propagation velocity, X, is the coordinate of the point where the charge hits the delay line (6), in this case the distance between this point and the end of the line (7).

The output voltage of the subtracter (20), which is equal to the difference (U ₁ -U ₂ ), is proportional to 2X-1 / V, and holds the information of the coordinate X corresponding to the coordinate of the light source. .. The adder circuit (19)
The voltages U ₁ and U ₂ are added to give an output voltage proportional to 2Δt + 1 / V, which is the photon-generated laser pulse of the photon of the test radiation towards the photomultiplier (3). Means that it holds information about the arrival time for.

The outputs of the adder circuit (19) and the subtractor circuit (20) are respectively input terminals (21) (2) of the data storage processing device (23).
Applied to 2) and stored in this device. Polychromator
If (17) is installed, its spectral characteristics are captured instead of the spatial position of radiation. This is because the test radiation is dispersed and the coordinates of the point where the photon hits the photocathode (4) are determined by the wavelength of the photon.

The pulse of the photodiode (2) is set to
It can be used as a trigger signal for the amplitude converters (12) (13).
Since the signal of (3) can be detected, all noise pulses other than this short time leave the measurement path. Therefore, the number of noise pulses in the photoelectric multiplier is equal to 10 ³ (pulses / second),
If the conversion range of the time / amplitude converter is 100 ns, the repetition rate of the pulsed laser emitter is high. (10 ⁴ … 10
^{Even at 5} Hz), the noise pulse detection rate is substantially 1 sample / second or less, and high measurement accuracy can be realized.

In order to obtain the two-dimensional spatial position of the subject radiation, the photoelectric multiplier (3) may be provided with another delay line (not shown) at right angles to the delay line (6).

Furthermore, in this case, the device according to the invention further comprises a further pair of time-amplitude converters and inputs whose stop inputs are connected to both ends of the second delay line. Add another subtraction circuit connected to the output, or add a time-amplitude converter with both inputs connected to both ends of the second delay line.

[0041]

According to the present invention, since only one measurement channel is required to obtain the space and time characteristics regarding the radiated light under investigation, the structure of the apparatus can be simplified. In addition, the signal derived from the anode of the photoelectric multiplier can be used as an information holding signal in the measurement channel, and by synchronizing the time / amplitude converter, it is possible to improve the accuracy of space and time characteristic evaluation.

[Brief description of drawings]

1 is a schematic block diagram of a device according to the invention for determining the spatial and temporal characteristics of weak radiation emitted by an object.

[Explanation of symbols]

(1) Laser pulse radiator (2) Photodiode (3) Photoelectric multiplier (4) Photocathode (5) Multiplication system (6) Delay line (7) (8) Delay line termination (9) Time / amplitude converter Stop input terminal of (11) (10) Stop input terminal of time / amplitude converter (12) (11) (12) Time / amplitude converter (13) Start input terminal of time / amplitude converter (11) (14) ) Start input end of time / amplitude exchanger (12) (15) Semi-transparent mirror (16) Subject holder (17) Polychrometer (18) Lens (19) Adder circuit (20) Subtractor circuit (21) (22) Input terminal of data storage processor (23) Data storage processor (U ₁ ) Output voltage of time-amplitude converter (11) (U ₂ ) Output voltage of time-amplitude converter (12) Photodiode pulse Time interval from generation to charge arrival at the delay line (I) Delay line length (V) Charge propagation velocity along the delay line (X) Coordinates of point where charge hits the delay line

Continuation of the front page (72) Inventor Prat Nurmakovich Treutaev Soviet Union Moscow Reninsky Gory MGU Corpus de Komnat 332 (72) Inventor Alexander Paulovich Sikrinov Soviet Union Moscow Lomonosovsky Prospect 23 Inventor 413 (72) Michael Rvimovich Ein Bund Soviet Union Leningrad Ulyzer Manchester Skaya 6 Kavi 10 (72) Inventor Jorzie Alexandrovich Menshikov Soviet Union Leningrad Prospect Bolshevikov 3 Corps 1 Kavi 15

Claims (1)

[Claims] 1. A device for determining the space and time characteristics of weak synchrotron radiation emitted from a subject, which irradiates the subject holder (16) and the subject to generate weak synchrotron radiation. An optical pulse radiator (1) and an anode in the form of a delay line (6), and the weak emitted light emitted from the subject,
Photoelectric multiplier (3) for converting into an electric signal, and the optical radiator
Generator that generates an electric pulse in synchronization with the pulse of (1)
(2) and one input terminal (13) are the electric pulse generator
First time-amplitude converter (11) connected to the output terminal of (2)
And a data storage processing device (23), the addition circuit (19), the subtraction circuit (20), and one input terminal,
A second time-amplitude converter (12) connected to the output end of the electric pulse generator (2) and the other input end (10) connected to one end (8) of the delay line (6) And the other input terminal (9) of the first time-amplitude converter (11) is connected to the delay line.
It is connected to the other end (7) of (6) and is connected to the both time / amplitude converter (1
The output terminals of 1) and 12) are connected to the addition circuit (19) and the subtraction circuit (2
0), and the output terminals of the adder circuit (19) and the subtractor circuit (20) are connected to both input terminals (21) and (22) of the data storage processing device. And the device.