JP2672756B2 - Solid streak camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid streak camera for measuring the temporal intensity change of pulsed light by directly scanning the pulsed light from a light source.

[0002]

2. Description of the Related Art Phenomena involving absorption and emission of light in a substance are one of the fundamental natural phenomena due to the transition of quantum states in the substance. It is the theme. High-speed pulsed light is a transient phenomenon of absorption and emission of this light, and its measurement technique is very important for understanding this basic physical phenomenon. Among the high-speed pulsed light measurements, the fastest one that is currently in practical use is the method using a streak camera.

Regarding high-speed pulsed light measurement with a streak camera, the same applicant has made a measurement of an optical fiber by branching into probe light and monitor light (Japanese Patent Publication No. 3-54776). This will be briefly described.

The light source of the laser diode is caused to emit light for a predetermined repetition time and pulsed light is output. This pulsed light is branched, and one of them is used as the light for the probe and the other is used as the light for the monitor, and the light for the probe is given to the optical fiber to be measured. The light for monitoring is applied to the photocathode of the streak tube through the reference optical fiber, and the light for the probe from the measurement object is applied to a position different from the light for monitoring on the photocathode of the streak tube. Then, these lights become a streak image of the fluorescent screen of the streak tube, and the streak image is photographed by a video camera to measure the temporal intensity change of both the probe light and the monitor light from the measurement object. There is. This makes it possible to measure the relative change in light intensity, which makes high-speed pulsed light measurement better.

[0005]

In the streak camera described above, the wavelength region that can be measured is limited by the material of the photocathode of the streak tube. Light outside the wavelength range (for example, infrared light) cannot be measured. On the other hand, it seems that the problem can be solved by adopting a configuration in which a solid streak camera is used to directly scan the measurement light and then convert it into an electric signal. However, if an optical system for both the light for the probe and the light for the monitor is provided, the configuration becomes complicated and the device becomes large. The advantage of the streak camera is that it can measure the pulsed light at the highest speed, but there is a great risk that the advantage will be lost due to signal delays. If the optical system is configured in consideration of this, there is a problem that the configuration becomes highly accurate and complicated. Therefore, it is possible to further simplify this.

In view of the above-mentioned problems, the present invention enables high-speed pulsed light measurement for both the probe light and the monitor light with a simple structure, and measures the relative change in light intensity. It is to provide a solid streak camera with high resolution.

[0007]

In order to solve the above problems, the solid streak camera of the present invention scans light incident at a timing corresponding to pulsed light from a light source with an optical deflector, A solid-state streak camera that collects the scanned light on an image sensor, detects it, and outputs it as a detection signal. The streak camera splits the pulsed light into a first light for a probe and a second light for a monitor. Optical means for applying the first light to the object to be measured and applying the first light and the second light from the object to the optical deflector in a non-parallel manner.

The optical means uses the first pulsed light from the first pulsed light.
Half mirror that splits the second light and the first half mirror, and the first light that is placed on the second optical path and that has passed through the measurement target is reflected at a predetermined angle from the optical axis of the second light. And a second half mirror which is folded back so as to give to the optical deflector.

It may be characterized in that it further comprises a dispersion means for dispersing the light scanned by the optical deflector so as to make the position on the image sensor different depending on the wavelength dispersion.

The scanning direction of the optical deflector and the direction in which the first light and the second light are separated may be substantially parallel to each other.

The scanning direction of the optical deflector and the direction in which the first light and the second light are separated may be substantially perpendicular to each other.

The optical means is arranged on the optical path of the second light, and a first half mirror for splitting the incident pulsed light into a plurality of first light and second light having different wavelengths. ,
It is configured to include a second half mirror that folds back a plurality of first light beams that have passed through the measurement target so as to have a predetermined angle with the optical axis of the second light beam and applies the second half mirror to the optical deflector. May be a feature.

[0013]

In the solid-state streak camera of the present invention, the pulsed light from the light source is split into the first light for the probe and the second light for the monitor, and the first light is given to the object to be measured. Then, the first light from the measurement target is applied to the optical deflector in a non-parallel manner together with the second light, and the first light and the second light from the measurement target are scanned by the optical deflector to be scanned by the image sensor. Focus on top. At this time, since the first light and the second light are not parallel to each other, the light collecting positions on the image sensor are different. Therefore, in the image sensor, the first light and the second light
Light is detected, and the detection signal contains a probe component and a monitor component at different positions.

When the dispersion means is further provided, the focus positions of the first light and the second light on the image sensor are different depending on the wavelength. Therefore, the detection signal for the probe depending on the wavelength. And a detection signal for monitoring are obtained.

[0015]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration example of a solid streak camera of the present invention. This solid-state streak camera has a polarizer 102 and an aperture 1 as an optical system of pulsed light detection means.
03, an optical deflector 104, a Fourier transform lens 105, an image sensor 106, and a controller 121 and a high voltage circuit 123 as a control system of the pulsed light detection means. Further, half mirrors 131 and 134 and mirrors 132 and ₁ are used as optical means for branching the probe light P ₁ to the measurement target sample 301 and the monitor light P _2.
33. Here, the half mirror 134 and the mirror 133 are arranged such that the light P ₁ that has passed through the sample 301 does not coincide with the optical path of the monitoring light P ₂ but has a slight angle. This separation angle is set to be larger than the deflection angle by the light deflector 104. The polarizer 102 converts the pulsed light P _L from the light source into linearly polarized light, and the aperture 103 allows only light having a predetermined diameter to pass. It is the one. The optical deflector 104 changes the direction of incident light according to the magnitude of the sweep voltage V _S. As the optical deflector 104, one having a structure as shown in FIGS. 2 to 3 using a crystal having electro-optical properties is used. FIG. 2 is a so-called double prism type, in which two prism-shaped crystals are laminated by inverting their optical axes. When a sweep voltage V _S is applied in the vertical direction of the double prism type optical deflector, the direction of incident light is bent at an angle proportional to the voltage. FIG. 3 is a so-called quadruple electrode type, in which a sweep voltage V _S is applied to deflect incident light as shown.

The Fourier transform lens 105 is the optical deflector 1
The light that has passed through 04 is condensed and Fourier-transformed on the image sensor 106 to form a far-field image. The image sensor 106 converts the light condensed by the Fourier transform lens 105 into an electric signal, and outputs this electric signal as a detection signal V _OUT according to the read pulse V _READ .
An array element of InSb or Ge is also used for receiving infrared light. 4, the optical deflector 104, a Fourier transform lens 105, shows the positional relationship between the image sensor 106 and the light P _1, P _2, of the spot light P _1, P ₂ in the deflection direction of the optical deflector 104 It is shown that they are lined up.

The controller 121 controls the trigger signal V _TRIG.
Sweep pulse V _SWEEP and read pulse V _READ
To generate the high voltage circuit 123 and the image sensor 10 respectively.
6 is output. Here, the trigger signal V _TRIG is output from the LD driver light source for driving the laser diode LD (light source) and is synchronized with the pulsed light P _L. The high-voltage circuit 123 is composed of a klytron element, an avalanche transistor, etc., and has a sweep pulse V
_A high voltage for driving the optical deflector 104, that is, a sweep voltage V _S is generated from _SWEEP and output to the optical deflector 104.

Next, the operation of the solid streak camera will be described.

The pulsed light P _L from the light source is _generated by the polarizer 102.
Is converted into a linearly polarized light by the half mirror 131 and split into a probe light P ₁ and a monitor light P ₂ by the half mirror 131. The light P ₁ for the probe is reflected by the mirror 132, and then the sample 301
Incident on. The light P _{1 that} has passed through the sample 301 is reflected by the mirror 1
After being reflected by 33, it is superposed on the monitor light P ₂ by the half mirror 134. At this time, the light P _{1 that} has passed through the sample 301 is slightly deviated from the monitor light P _{2 in} angle. Aperture 10 of light P ₁ and P ₂
In step 3, only a predetermined amount of light passes and the light deflector 104
Incident on. Light P ₁ , P incident on the optical deflector 104
_The beam of light ₂ is bent by the optical deflector 104, is condensed by the Fourier transform lens 105, and is reflected by the image sensor 106.
The image is converged and imaged. On the other hand, the trigger signal V _TRIG is input to the controller 121, and the pulsed light P _L from the light source is input.
Sweep pulse V _SWEEP , read pulse V _READ, and sweep voltage V _S from high-voltage circuit 123
Is output. The sweep voltage V _S has a time waveform as shown in FIG. 5A, and due to the deflection by the optical deflector 104, the time waveforms of the lights P ₁ and P ₂ as shown in FIG. Converted to waveform. At this time, since the incident angles of the lights P ₁ and P ₂ are different, the image forming positions on the image sensor 106 are different. Therefore, the spatial waveforms of the lights P ₁ and P ₂ as shown in FIG. 5C are imaged on the image sensor 106.

In this way, the temporal intensity changes of the probe light P ₁ and the monitor light P ₂ are converted into spatial intensity changes in the deflection direction. Then, it is detected by the detection elements of the image sensor 106 on those focused spots, and the detection signal V _OUT is read and output at the timing of the read pulse V _READ . By subjecting the component of the probe light P _{1 and} the component of the monitor light P ₂ of the detection signal V _OUT to a predetermined calculation (subtraction, division, etc.), only changes such as absorption and scattering by the sample 301 are caused. You can take it out.
In particular, the component of the light P ₂ for monitoring and the light P from the sample 301
_{Since the 1} component is detected separately, even if there is a slight change in the light P ₂ , it is possible to detect the relative change in the light P ₁ . Therefore, it is possible to better measure the optical properties of the measurement target.

The present invention is not limited to the above-mentioned embodiment, but various modifications are possible.

FIG. 6 shows an application to the case where the sample 301 uses a material whose physical properties are changed by light (for example, Photoreflactive crystal). Replace the half mirrors 131 and 134 with the dichroic mirror 131.
a and 134a, and the light modulation element 138 is arranged between the dichroic mirror 134a and the mirror 133. The dichroic mirrors 131a and 134a are adapted to reflect the light having the wavelength of the light P ₁ . Excitation light P on sample 301
A part of ₃ is branched and inputted together with the DC light P ₁ for the probe, and separated and superposed by the dichroic mirrors 131a and 134a. In addition, the light modulation element 13
Reference numeral 8 allows the light P ₁ to pass while the polarizer 102 is sweeping by the pulse signal from the controller 121.

FIG. 7 shows changes in the excitation light P ₃ and the light P ₁ . The light P ₁ passing through the sample 301 changes according to the change of the excitation light P ₃ (FIG. 7A) (see FIG. 7A).
(B)), the light P ₁ is passed during the sweep time (FIG. 7 (c)). If the probe light P ₁ is DC light, the image sensor 106 will be saturated, but this saturation is suppressed because the light modulation element 138 allows the light P ₁ to pass only for the sweep time.

In FIG. 8, the dichroic mirrors 132a, 132b, 133a, 1 are replaced with the mirrors 132, 133.
33b is arranged to allow the light P ₁ for the probe to have a different wavelength λ.
_The sample 301 is divided into ₁ , λ ₂ , and λ ₃ and is given to the sample 301. As a result, different wavelengths are detected at different positions of the image sensor 106.

In addition, in order to examine the change in polarization, it is possible to measure it by placing a polarizer in front of the aperture 103.

FIG. 9 shows a change in the physical properties of the sample 301 for each wavelength by wavelength dispersion, and this is achieved by providing a prism 108 in front of the image sensor 106. It is important that the direction of wavelength dispersion is not parallel to the scanning direction, and it is desirable to keep it vertical.
A two-dimensional image sensor is used as the image sensor 106. FIG. 10 schematically shows the positions where the light P ₁ and P ₂ are irradiated on the image sensor 106. As a result, like the image sensor 106, the detection signal V _OUT contains a component for each wavelength, and it becomes possible to measure the physical property change for each wavelength.

The above-described configuration of FIG. 4 has the image sensor 1
In order to measure only one one-dimensional image sensor as 06, the directions in which the light P ₁ and P ₂ are separated and the scanning direction are parallel to each other. If a sensor is used, the direction in which the lights P ₁ and P ₂ are separated may be perpendicular to the scanning direction. FIG. 11 shows the situation, and the mirror 1
This is achieved by changing the reflection angle of the 33 or half mirror 131. FIG. 12 schematically shows the positions where the light P ₁ and P ₂ are irradiated on the image sensor 106.

Further, due to the wavelength dispersion, the sample 3 for each wavelength is
It is also possible to check the physical property change of No. 01, and this is achieved by providing the prism 108 in front of the image sensor 106 as shown in FIG. FIG. 14 schematically shows the positions where the light P ₁ and P ₂ are radiated on the image sensor 106. The detection signal V _OUT contains a component for each wavelength, and the physical properties for each wavelength are shown. You will be able to measure changes.

[0029]

As described above, according to the present invention, since the first light and the second light are non-parallel, the converging positions on the image sensor are different. The first light and the second light are respectively detected, and detection signals for the probe and the monitor can be obtained, which enables better measurement of the optical properties of the measurement target.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a solid streak camera of the present invention.

FIG. 2 is a diagram showing a configuration example of an optical deflector.

FIG. 3 is a diagram showing a configuration example of an optical deflector.

FIG. 4 is an optical deflector 104, a Fourier transform lens 105,
Diagram showing the positional relationship between the image sensor 106 and the light P _1, P _2.

FIG. 5 is a diagram showing a sweep voltage V _S and time waveforms and spatial waveforms of lights P ₁ and P ₂ .

FIG. 6 is a diagram showing application to a case where a sample is made of a material whose physical properties are changed by light.

FIG. 7 is a diagram showing changes in excitation light P ₃ and light P ₁ when the probe light P ₁ is DC light.

FIG. 8 shows the light P ₁ for the probe having different wavelengths λ ₁ ,
The figure which shows the modification which divided into (lambda) ₂ and (lambda) ₃ and was given to the sample 301.

FIG. 9 is a diagram showing a modified example in which changes in physical properties of the sample 301 are examined by wavelength dispersion.

FIG. 10 is a diagram schematically showing a position where light P ₁ and P ₂ are irradiated on the image sensor 106.

FIG. 11 is a diagram showing a modified example in which the direction in which the lights P ₁ and P ₂ are separated and the scanning direction are perpendicular to each other.

FIG. 12 is a diagram schematically showing the positions where light P ₁ and P ₂ are irradiated onto the image sensor 106.

FIG. 13 is a diagram showing a modification in which the direction in which the lights P ₁ and P ₂ are separated and the scanning direction are perpendicular to each other.

FIG. 14 is a diagram schematically showing a position where light P ₁ and P ₂ are irradiated on the image sensor 106.

[Explanation of symbols]

102 ... Polarizer, 103 ... Aperture, 104 ... Optical deflector, 105 ... Fourier transform lens, 106 ... Image sensor, 108 ... Prism, 121 ... Controller, 12
3 ... High-voltage circuit, 301 ... Sample, P ₁ , P ₂ ... Light, 13
1,134 ... Half mirror, 132, 133 ... Mirror.

Claims (6)

(57) [Claims] 1. A light deflector scans light incident at a timing corresponding to pulsed light from a light source, collects the light scanned by the light deflector onto an image sensor, detects the light, and outputs it as a detection signal. In the solid streak camera, the pulsed light is branched into a first light for a probe and a second light for a monitor, and the first light is applied to a measurement target. A solid-state streak camera comprising optical means for imparting the first light and the second light non-parallel to the light deflector. 2. The optical means is disposed on the second optical path, a first half mirror that splits the incident pulsed light into first light and second light, and measures the measurement target. A second light which is returned to the optical deflector by folding back the transmitted first light so as to have a predetermined angle with the optical axis of the second light.
2. The solid streak camera according to claim 1, further comprising: 3. A dispersion means is further provided to disperse the light scanned by the light deflector so as to make the position on the image sensor different depending on the wavelength dispersion. The solid streak camera described. 4. The solid streak camera according to claim 3, wherein a scanning direction of the optical deflector and a direction in which the first light and the second light are separated are substantially parallel to each other. . 5. The solid streak camera according to claim 3, wherein a scanning direction of the optical deflector and a direction in which the first light and the second light are separated are substantially perpendicular to each other. . 6. The optical means comprises a first half mirror for splitting incident pulsed light into a plurality of first light and second light having different wavelengths, and the light of the second light. A plurality of the first units arranged on the road and transmitted through the measurement target.
2. The second half mirror which returns the light of the second light so as to have a predetermined angle with the optical axis of the second light and gives the light to the optical deflector. Solid streak camera.