JPH0756463B2 - 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 streak camera, and more particularly to a solid-state streak camera for measuring spatial intensity changes by directly scanning 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.

High-speed pulsed light measurement with a streak camera will be briefly described with reference to FIG. The pulsed light P _L from the light source is incident on the slit 602, and the slit image of the pulsed light P _L is converged and imaged at a predetermined position on the photocathode 604 via the lens 603. Pulsed light P _{L on the} photocathode 604
Electrons are emitted by the photoelectric effect of. The electrons emitted from the photocathode 604 are accelerated by the mesh-shaped acceleration electrode 605 and converged by the convergent electron lens 611. The electrons converged by the converging electron lens 611 pass through the deflection field of the deflection plate 606 and form a streak image on the fluorescent screen 607. The deflector 606 has a sweep voltage V generated by the sweep generator from a trigger signal at a timing corresponding to the pulsed light.
_S is applied to scan electrons passing through the deflection field of the deflection plate 606 (in this figure, scanning is performed from top to bottom). Therefore, the temporal intensity change of the pulsed light P _L is
The streak image of the fluorescent screen 607 is converted into the spatial intensity change in the scanning direction. This streak image is photographed by a still camera or a video camera (not shown), and the temporal intensity change of the pulsed light P _L is measured.

When high-speed pulsed light is measured with a streak camera, it is desirable that the image formed on the photocathode 604 formed by the input optical system is small in order to improve time resolution, so the slit 602 is preferably thin. On the other hand, in order to increase the sensitivity, it is better that the light amount is large. Regarding this contradictory problem, in the invention described in "JP-A-62-50626",
Resolved by the same applicant. In the present invention, a glass rod is provided in the input optical system to increase the amount of light and equivalently pass through a narrow slit.

[0005]

In the above-described streak camera, when an attempt is made to obtain a measurement result by an electric signal, "light →
Since the conversion of "electron → light → electron" is performed, this is
Further simplification is considered. When the measurement light is directly scanned and converted into an electric signal, the device is significantly downsized and simplified, convenience such as portability is increased, and light in a wavelength region where photoelectric conversion is difficult (for example, infrared light). ) Will be able to measure. In this case, since the measurement light is directly scanned, it is incident on the deflector (optical deflector) so that the scanning direction does not shift and the position where the pulsed light converges (focus spot) does not shift. The light must be parallel rays. However, the state of the measurement light differs depending on the situation, and if the scanning direction is shifted or the condensing spot becomes large, the spatial resolution is lowered and the time resolution is lowered. As described above, when the measurement light is directly scanned and converted into an electric signal, the resolution is lowered depending on the measurement state, and it is necessary to consider the simplification of the device in consideration of this problem.

In view of the above-mentioned problems, the present invention is to provide a solid-state streak camera having a configuration in which the measurement light is directly converted into an electric signal and the resolution is not lowered depending on the measurement state.

[0007]

The solid streak camera of the present invention includes an optical deflector for scanning pulsed light at a timing corresponding to the pulsed light from a light source, and a light deflector for condensing the light scanned by the optical deflector. A Fourier transform lens and an image sensor for detecting the light condensed by the Fourier transform lens and reading a detection signal at the timing of a read pulse corresponding to the pulsed light are provided, and the pulsed light is provided between the light source and the optical deflector. It has a collimator composed of at least two lenses that adjust the path of the light beam to make it parallel rays.

Further, the collimator may be detachably attached to the housing containing the optical deflector, the Fourier transform lens and the image sensor so that the collimator corresponding to the state of the pulsed light is used. Alternatively, the collimator may be built in the housing so that the device can be made compact.

[0009]

Since the scanning by the optical deflector is at the timing corresponding to the pulsed light, the temporal intensity change of the pulsed light is converted into the spatial intensity change in the scanning direction. The light scanned by the optical deflector is condensed by the Fourier transform lens, detected by the detection element of the image sensor on the condensed spot, and the detection signal is read at the timing of the read pulse in correspondence with the pulsed light.

Here, since the pulsed light is adjusted by the collimator according to the state of the pulsed light and converted into parallel rays, the spread of the focused spot is prevented.

[0011]

Embodiments of the present invention will be described with reference to FIGS. FIG. 1 shows a solid-state streak camera according to an embodiment of the present invention. As an optical system of this solid-state streak camera, a polarizer 102, an aperture 103, an optical deflector 104, a Fourier transform lens 105, and an image sensor 106 are provided in a collimator 101 and a housing 180. Further, a controller 121 and a high voltage circuit 123 are provided as a control system.

The collimator 101 is detachably provided in the pulse light P _L inlet of the solid streak camera housing 180, and has two convex lenses 101a and 101a having the same focal length.
It is composed of 01b. The convex lens 101a is fixed and the other convex lens 101b is made movable, the distance between them is made variable, and the focusing of the pulsed light P _L is adjusted. An example of a movable convex lens adjustment mechanism is shown in FIG. With this adjusting mechanism, the convex lenses 101a, 10a
The interval of 1b is precisely adjusted. This collimator 1
The state of adjusting the focusing of the pulsed light P _{L at} 01 is shown in FIG. FIG. 3A shows the case where the pulsed light P _L is converged, and the convex lens 101 is more than twice the focal length f.
The interval between a and 101b is shortened to make the pulsed light P _L parallel light. FIG. 3B shows the case where the pulsed light P _L is parallel, and the interval between the convex lenses 101a and 101b is twice the focal length f to make the pulsed light P _L parallel.
FIG. 3C shows the case where the pulsed light P _L is spread, and the interval between the convex lenses 101a and 101b is made wider than twice the focal length f to make the pulsed light P _L parallel light. This adjustment is possible in a wide range by replacing the collimator 101.

The polarizer 102 is a pulsed light P _L from the light source.
Is converted into linearly polarized light. Aperture 103
Is designed to pass only light in a predetermined direction. 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. 4 to 5 using a crystal having electro-optical properties is used. FIG. 4 is a so-called double prism type in which two prism-shaped crystals are bonded by inverting their optical axes. When a voltage is applied in the vertical direction of this double prism type optical deflector, the direction of incident light is bent at an angle proportional to the voltage. FIG. 5 is a so-called quadruple electrode type in which a voltage is applied as shown in the figure to deflect incident light.

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 an 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 .

The controller 121 generates a sweep pulse V _SWEEP and a read pulse V _READ from the trigger signal V _TRIG corresponding to the pulsed light P _L from the light source and outputs them to the high voltage circuit 123 and the image sensor 106, respectively. The high voltage circuit 123 _changes the sweep pulse V _SWEEP from the optical deflector 1
The driving high voltage 04, that is, the sweep voltage V _S is generated and output to the optical deflector 104.

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

The pulsed light P _L from the light source is generated by the collimator 1
In 01, the extent of spread is corrected. Collimator 101
The pulsed light P _L that has passed through is converted into linearly polarized light by the polarizer 102, and only light of a predetermined size passes through the aperture 103 and enters the optical deflector 104. Optical deflector 104
The pulsed light P _L incident on is bent in its course by the optical deflector 104 and is condensed by the Fourier transform lens 105,
The image is focused on the image sensor 106 to form an image. By adjusting the degree of spread of the pulsed light P _L incident on the optical deflector 104 by the collimator 101, the position of the focused spot is adjusted, which is shown in FIG. Figure 6 (b)
Shows a state in which light that has spread to the light deflector 104 is incident, and the converging spot is spread, and the time resolution of the device is reduced. Collimator 1
The convex lenses 101a, 101
The image sensor 10 of the focused spot is adjusted by adjusting the interval b.
When the half width of the detection signal V _OUT of FIG.
As shown in (a), the focused spot is the image sensor 10
6 and has the smallest diameter.

On the other hand, the trigger signal V _TRIG is the controller 1
21, a sweep pulse V _SWEEP and a read pulse V at a timing corresponding to the pulsed light P _L from the light source.
_The sweep voltage V _S is output from the _READ and high voltage circuit 123. The sweep voltage V _S has a time waveform as shown in FIG. 7A, and by the deflection by the optical deflector 104, the sweep voltage V _S shown in FIG.
The time waveform of the pulsed light P _L as shown in (b) is converted,
A spatial waveform as shown in FIG. 7C, that is, the image sensor 106.
The image forming position is on the upper side. In this way, the temporal intensity change of the pulsed light is converted into the spatial intensity change in the deflection direction.

The pulsed light P _L deflected by the optical deflector 104 is image sensor 106 on the focused spot.
Is detected by the detection element of. The detection signal V _OUT is read and output at the timing of the read pulse V _READ . By adjusting the collimator 101 to the best point where the focused spot is minimized, the spatial resolution is optimized and the maximum time resolution of this device is obtained.

The present invention is not limited to this embodiment, but the following modifications are possible. Here, the same reference numerals are used for the same or equivalent parts as those in the above-described embodiment.

Regarding the collimator, as shown in FIG.
Convex lenses 101a and 10 having different focal lengths
With the configuration using 1b, the beam diameter can be changed. In the figure, f ₁ and f ₂ are convex lenses 101a and 1a.
The focal length is 01b, and the beam diameter is about "f ₁ / f ₂ " times. When the beam diameter is reduced, the amount of light passing through the aperture increases and the sensitivity improves. Also,
FIG. 9 shows three lenses 101p, 101q, 101r.
An example configured using is shown. In this collimator, two lenses are moved so that the beam is collimated and the beam diameter is reduced at the same time. By doing so, it is possible to measure light with different beam diameters with high sensitivity.

The collimator may be provided in the housing as shown in FIG. FIG. 10 shows that the convex lenses 101a and 101b forming the collimator 201 are provided in the housing 181.
Then, as shown in FIG. 11, the polarizer 102 and the aperture 1
It may be provided between 03. FIG. 11 shows that the convex lenses 101a and 101b forming the collimator 301 are provided between the polarizer 102 and the aperture 103. In these cases, although the adjustment range of the collimator is limited, there is a feature that the collimator can be downsized due to its structure.

[0023]

As described above, according to the present invention, since the measuring light is directly converted into an electric signal, the structure of the device is simplified, and the degree of spread of the pulsed light incident on the optical deflector is adjusted by the collimator to collect the light. Since the spot is adjusted to the best point so as to be the minimum, the spatial resolution is improved and the maximum temporal resolution can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a lens adjusting mechanism of a collimator.

FIG. 3 is an explanatory diagram showing how to adjust the focusing of pulsed light.

FIG. 4 is a configuration diagram of an example of an optical deflector.

FIG. 5 is a configuration diagram of an example of an optical deflector.

FIG. 6 is an explanatory view showing how a focused spot is adjusted by a collimator.

FIG. 7 is a diagram showing a relationship between a time waveform of a sweep voltage, a time waveform of pulsed light, and a spatial waveform of pulsed light.

FIG. 8 is another configuration diagram of the collimator.

FIG. 9 is another configuration diagram of the collimator.

FIG. 10 is a block diagram of another embodiment of the present invention.

FIG. 11 is a configuration diagram of another embodiment of the present invention.

FIG. 12 is a configuration diagram of a conventional example.

[Explanation of symbols]

101 ... collimator 101a ... lens 101b ... lens 101c ... Lens 101p ... lens 101 q ... lens 101 r ... lens 104 ... optical deflector 105 ... Fourier transform lens 106 ... image sensor 162 ... optical deflector 201 ... collimator 301 ... collimator P _L ... pulse Light V _OUT … Detection signal V _READ … Read pulse

Claims (3)

[Claims] 1. An optical deflector for scanning pulsed light at a timing corresponding to pulsed light from a light source, a Fourier transform lens for Fourier transforming and condensing the light scanned by this optical deflector, and this Fourier transform. An image sensor that detects light condensed by a lens and reads a detection signal at the timing of a read pulse corresponding to the pulsed light, and adjusts the path of the pulsed light between the light source and the optical deflector. A solid streak camera having a collimator composed of at least two lenses for making parallel light rays. 2. The solid streak camera according to claim 1, wherein the collimator is attachable to and detachable from a housing that houses the optical deflector, the Fourier transform lens, and the image sensor. 3. The solid streak camera according to claim 1, wherein the collimator is incorporated in a housing that houses the optical deflector, the Fourier transform lens, and the image sensor.