JPS62282229A - Apparatus for correcting distortion of streak image - Google Patents

Abstract

PURPOSE:To easily analyze a streak image, by correcting the distortion of the streak image of light to be measured when a repeated optical phenomenon is observed by a streak camera. CONSTITUTION:The slit 32 on a slit plate 31 is opened horizontally and, if light is incident to said slit 32, the photoelection group from a photoelectric surface 33 is deflected by a vertical deflection electrode 25a and a horizontal deflection electrode 25b, and projected to a place, which is parallelly moved by TV (t0) in a vertical direction and by TH(t0) in a horizontal direction, on an output fluorescent surface 27 as compared with such a case that any deflection is not performed. As mentioned above, the conversion of an image is performed on the basis of the shift quantity on the fluorescent surface 27 in the horizontal direction when the slit 32 of the input optical system of a streak camera is opened in the horizontal direction. Then, by correcting the bending of a streak image to obtain the streak image free from distorsion, the analysis of the streak image is easily performed.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Industrial Application Field] The present invention relates to a streak camera device for observing optical phenomena, and in particular to a two-dimensional streak image of measured light due to a repeated light emission phenomenon. The present invention relates to a streak image distortion correction device that corrects target curvature.

[Conventional technology]

Conventionally, streak cameras have been used to observe optical phenomena with high temporal resolution.

Fig. 3 shows the overall configuration of a conventional optical measurement device using a streak camera, where 11 is the emitted light to be measured, 12 is the streak camera, 13 is a high-sensitivity television camera, 14 is a signal transmission cable, and 15 is image processing. It is a device.

In the figure, optical phenomena are displayed on a fluorescent surface by a circular scan streak camera 12, scanned by a high-sensitivity television camera 13, converted into electrical signals, and analyzed and processed by an image processing device 15. .

Figure 4 shows the circular scan streak tube in Figure 3, Figure 5 shows the deflection voltage waveform of the streak tube, and Figure (A) shows the vertical deflection voltage waveform. (B) is a diagram showing the horizontal deflection voltage waveform, Figure 6 is a diagram showing the photoelectron arrival point on the fluorescent surface and its extension surface in elliptical sweep, and Figure 7 is a diagram showing the case where repeated optical phenomena are observed by elliptical sweep. In the figures, (A) is a repetitive light emission waveform diagram, (B) is a deflection voltage waveform diagram, and (C) is a diagram showing a streak image. In the figure, 21 is a photocathode, 22 is a mesh electrode, 23.24 is a focusing electrode, 25a is a vertical deflection electrode, 25b is a horizontal deflection electrode, 26a and 26b are a sinusoidal deflection voltage generating circuit, 27 is a fluorescent surface, and El , Et is a power supply, R is a resistor, and P1 to pro and P+' to PIG' are photoelectron arrival points.

Next, the operation will be described. The light to be measured is converted into photoelectrons by the photocathode 21 and accelerated by the mesh electrode 22. The converging electrodes 23 and 24 form electron lenses that converge photoelectrons generated at the photocathode 21 onto the fluorescent surface 27, and the photoelectrons accelerated by the mesh electrode 22 converge through these electron lenses to form a pair of flat plates. The light is deflected by a vertical deflection electrode 25a and a horizontal deflection electrode 25b, and reaches the fluorescent surface 27. Vertical deflection electrode 25a, horizontal deflection electrode 25
sine wave deflection voltage generating circuits 26a and 26b, respectively.
Therefore, the sine wave voltage V as shown in FIGS. 5(A) and (B)
, ,V, are applied.

For example, the voltage applied to the vertical deflection electrode 25a is V+
PI), and the voltage applied to the horizontal deflection electrode 25b is a sine wave voltage of Vz pp on which a bias voltage of approximately 2/2 is superimposed, and these voltages V
, ,V, are phase shifted by π/2. Therefore, by applying voltages v,,y, to the deflecting poles 25a, 25b, ■? An elliptical sweep with the center shifted in the horizontal direction by a bias voltage of /2 is performed, and by appropriately selecting the values of V, ,V,, for example, the time t"t,,t,...
The photoelectrons incident at t9 reach points P, , P, .

...P is reached.

Further, the frequency of the sine wave voltage applied to the vertical deflection electrode 25a and the horizontal deflection electrode 25b is set to an integer of the repetition frequency of the light to be measured. For example, a sine wave synchronized with the frequency of laser light that excites the observation target is generated and used as the sine wave voltage to be applied. By setting the sinusoidal voltage applied to the vertical deflection electrode 25a and the horizontal deflection electrode 25b in this way, the repeatedly occurring phenomenon to be measured is superimposed on the same position on the output fluorescent surface 27, and In addition to being able to accumulate brightness (energy) in
The phenomenon during the return sweep can be removed from the output fluorescent surface 27, as shown from point P to point P in FIG.

Next, for example, a repeated light phenomenon as shown in FIG. 7(A),
When sweeping with the voltage waveform shown in the same figure (B), the same figure (
A streak image is formed on the fluorescent surface 27 as shown in C). At this time, the streak images P, ~P4 of the optical phenomenon from t''To to t=T are accumulated on the fluorescent surface 27, but the streak images of the optical phenomenon from L=7. to t-T are accumulated on the fluorescent surface 27. Images P, ~P, are not formed on the fluorescent surface.Therefore, double exposure is performed by preventing long-duration phenomena or light phenomena whose repetition frequency is greater than the sweep frequency from overlapping on the fluorescent surface. It is possible to prevent t=
Streak image P1 of optical phenomenon from T,' to L=T,'
'~P,' are overlapped at the same position as P, ~P, respectively, and energy is accumulated on the fluorescent surface.

Figure 8 shows the T of a streak image in a conventional optical measuring device.
This is a diagram for explaining the readout and storage by the V right camera, and numeral 28 in the diagram is a frame memory.

As shown in the figure, the streak image obtained on the fluorescent surface 27 by the aforementioned elliptical sweep is read out by scanning the fluorescent surface with a TV camera, etc., and the image signal is transferred to an A/D converter.
(not shown) in a large-capacity digital memory 28.
(hereinafter referred to as frame memory). The frame memory 28 is a two-dimensional memory having NXN pixels, and stores the streak image obtained on the output fluorescent surface 27 of the streak tube as one image as shown in the figure.

This N is usually about N=512.

9 and 10 are diagrams showing a frame memory, and FIG. 11 is a diagram showing a streak image stored in the frame memory.

In the figure, the position of each pixel in the frame memory is expressed as (i, j
), where O < i, j < N, and pixel (i, j)
The luminance value recorded in is expressed as l (i, j), and as shown in Figure 9, i is the horizontal axis of the frame memory and corresponds to the horizontal axis on the fluorescent surface, and `` is the vertical axis of the frame memory. The axis corresponds to the time axis of the streak image.

Here, as shown in FIG. 10, a certain area AV (io
, i+), AH(jo, L) are defined as follows.

AV(io, i+) −((i+j) i i,<
i<;I, o-≦-j<N)AH(io,L)
−f(i,j) I O−≦−1<N, jo<J
'L) Also, as shown in FIG. 11, information regarding the luminance IV (io, i, j), If
i) is defined as follows.

Iv(io, i++J) ”Σ I(i, j),
o< 4 <q[17(jo, j, i) =Σ I(
i, j), 0-≦-i<+1j”L.

As shown in FIG. 11, IV(io, i+, D is A
V(i,.

i+) for 1 for each j from 1=i0 to i=i
.

If (()., 5, 1) is AI
(j ”jo for each i in (ja, j+)
It is the integral from J−L. That is, in the vertical direction, the integral value of luminance from 10 to 11 for each scanning line is determined as IV, and in the horizontal direction, assuming a vertical line as the scanning line, along this vertical line The integral value of luminance from Jo to jl obtained for each vertical scanning line is designated as III.

In the conventional device, ■ν(io, i++j
).

01(jo, j+, i) and performs these analyzes and processes.

[Problem that the invention seeks to solve]

However, in the conventional circular scan streak system, the streak image is bent into an elliptical shape, which causes a disadvantage.

FIG. 12 is a diagram for explaining the bending of a streak image by a conventional circular scan streak system.
FIG. 13 is a diagram showing a streak image on a frame memory in time spectroscopy.
is a pinhole.

In the figure, when light having a temporally constant intensity is made incident on the streak camera through the pinhole 30 and swept, a streak image having a curve as shown in FIG. 12 is obtained in the frame memory 28.

Next, a spectroscope (not shown) is placed in front of the streak camera, and if the light phenomenon is split into spectra and incident on the streak camera, and an elliptical sweep is performed, the wavelength λ1. λ2. λ8
．． ... are separated by time.

A streak image with a bend as shown in Fig. 13 is
When directly analyzed using the above-mentioned Iv and rH, IV
(io, i+, j) has different wavelength information depending on j, and I) l(ja, j+, i) and III(jz, L
, ri have different wavelength information regarding the same i.

Therefore, if the streak image is directly analyzed using the above-mentioned IV and I)I, it is difficult, for example, to compare the changes over time for each wavelength or the changes in wavelength for each time.

The present invention is intended to solve the above-mentioned problems, and when optical phenomena are repeatedly observed using a streak camera, the streak image distortion of the light to be measured is corrected, and the streak image can be easily analyzed. An object of the present invention is to provide a streak image distortion correction device.

[Means for solving problems]

To this end, the streak image distortion correction device of the present invention uses a return sweep by applying sinusoidal voltages having a phase difference of 90 degrees to each other with a bias voltage superimposed on one side as deflection voltages on orthogonal deflection axes. A streak camera that prevents double exposure and observes a repeated light emission phenomenon at a synchro scan frequency that is an integer fraction of the repetition frequency, the streak camera detecting the amount of two-dimensional bending of the streak image due to the sweeping, The present invention is characterized in that the distortion of the streak image is corrected based on the detected amount of curvature.

[Effect]

In the streak image distortion correction device of the present invention, when a repeated light emission phenomenon is measured using a streak camera at a synchro scan frequency that is an integer fraction of the repetition frequency, a bias voltage is superimposed on one side and a phase difference of 90 degrees is established. The two-dimensional bending of the streak image caused by applying and sweeping a sinusoidal voltage having a sine wave voltage as the deflection voltage of the orthogonal deflection axes is detected, and the distortion of the streak image is corrected according to the amount of the detected bending. To facilitate image analysis.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining distortion correction of a streak image according to the present invention, and FIG. 2 is a diagram showing a streak image on a frame memory. In the figure, 31 is a slit plate, 32 is a slit, and 33 is a photocathode. It is.

In the figure, the slit 32 has a horizontal opening, through which light enters, and when the photoelectron group from the photocathode 33 enters the vertically polarized i-pole 25a at 1=1°, the photoelectron group changes the vertically polarized polarization to the pole 25a. , is deflected by the horizontal deflection electrode 25b, and is projected on the output fluorescent surface 27 at a location shifted in parallel by TV(to) in the vertical direction, T in the horizontal direction, and (tJ) relative to the case where nothing is deflected. In this way, when the slit of the input optical system of the streak camera opens horizontally, information in the horizontal direction of the slit is also projected onto the horizontal axis X on the fluorescent surface.Let y be the vertical axis of the fluorescent surface. Let the spatial axis in the direction be s
When (y) is the horizontal shift hit on the fluorescent surface, if s (y) is known, it is possible to perform image conversion based on 3(y) and correct the curvature of the streak image. becomes. This horizontal shift amount can be determined as follows.

The first method is to replace the slit in Figure 1 with a pinhole, inject continuous light, sweep the ellipse as described above, read out the image accumulated on the fluorescent surface with a high-sensitivity TV camera, and create a frame. Store in memory. The image stored in the frame memory at this time is shown in FIG.

In the streak image shown in FIG. 2, for each O-≦J<H, find "(JIJ, I), and let m(") be l with 1B (j, j, i) as MAX. That is, Iff (j, Lm(j)) > IH(j, Li)f
or all Q < i <)1 This m(j) is
represents the abscissa i where the streak image is stored,
The shift amount 5s(j) is 5s(j) = m(D-n+(N
/2), and sa (j) is calculated using the least squares method to calculate n
If the result obtained by applying the order polynomial is S(''), then s (D is the streak image record t9 at any j for the storage position of the streak image at j=N/2, as shown in FIG. It represents the horizontal shift amount of the position.

In the second method, the vertical deflection electrode 25a and the horizontal deflection electrode 25a
This method calculates the electron trajectory in the streak tube from the amplitude and phase shift of the sinusoidal deflection voltage applied to b and the deflection sensitivity of the streak tube. seek.

Streak image 1 (i.

j) is 5 for each "information on the horizontal axis of the slit"
For example, in time-resolved spectroscopy, the horizontal axis of the slit is the wavelength axis, but the wavelength information corresponding to each (i, j) is If λ(i, j), λ(i, D = λ(i-s(j), ~72) holds. Therefore, the obtained streak image t(i, j) is 1' (i, By converting D = l (i+5(j), j) and I' (i, j) and correcting it in the horizontal axis direction by the shift amount 5(j), the isovalue line (isowavelength line) in the vertical axis direction ) and the vertical axis direction (time axis) are parallel to each other.
, 0-≦-j, N by the method described above, and by performing simple image transformation, the rest is AV for I' (i, j), A11. according to the conventional method.
It is possible to measure and analyze TV and IH with extremely high precision compared to conventional methods.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the amount of two-dimensional curvature of a streak image is known in advance, and data on the frame memory is corrected by moving in a predetermined direction using this amount of curvature, thereby reducing distortion. Since it is possible to obtain streak images with no streaks, the method of time-resolved spectroscopy can be performed easily and with high precision even with a circular scan streak camera system. It can be used in a variety of fields, such as measurement and time-resolved spectroscopy using the circular scan method of semiconductor lasers in the field of optical communications, and has great effects.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining distortion correction of streak images according to the present invention, Fig. 2 is a diagram showing a streak image on a frame memory, and Fig. 3 is an overall configuration of a conventional optical measurement device using a streak camera. Figure 4 is a diagram showing the circular scan method streak tube in Figure 3, Figure 5 is a diagram showing the streak tube of the circular scan method in Figure 3,
The figure shows the deflection voltage waveform of the streak tube.
) is a diagram showing the vertical deflection voltage waveform, FIG. is a repeated optical phenomenon by elliptical sweep! ! The figure (A) is a repetitive emission waveform diagram, the figure (B) is a deflection voltage waveform diagram, the figure (C) is a diagram showing a streak image, and the figure (C) is a diagram showing a streak image.
The figure is a diagram for explaining how streak images are read out and stored by a TV camera in a conventional optical measuring device.
9 and 10 are diagrams showing the frame memory, and FIG. 11 is a diagram showing the streak image stored in the frame memory,
FIG. 12 is a diagram for explaining the bending of a streak image by a conventional circular scan streak system, and FIG. 13 is a diagram showing a streak image on a frame memory in time spectroscopy. DESCRIPTION OF SYMBOLS 11... Emission light to be measured, 12... Streak camera, 13... High sensitivity television camera, 14... Signal transmission cable, 15... Image processing device, 21... Photocathode, 22...・・Mesh electrode, 23. 24 ・・Set-up electric wire, 25a ・・vertical deflection finger, 25b ・・horizontal deflection electrode, 26a, 26b ・・sine wave deflection voltage generation circuit,
27... Fluorescent surface, El, E2... Power supply, R...
Resistance, P1 to P1°, Pl' to PI6'... Photoelectron arrival point, 28... Frame memory, 29... Pinhole plate, 30... Pinhole, 31... Slit plate, 32... ...Slit, 33...Photocathode Applicant Patent attorney representing Hamamatsu Photonics Co., Ltd.
Masaru HirukawaFigure 3Figure 5Figure 6Figure 7

Claims (4)

[Claims] (1) By applying and sweeping sinusoidal voltages having a phase difference of 90 degrees with a bias voltage superimposed on one side as deflection voltages of orthogonal deflection axes, double exposure due to return sweep is prevented and repeated A streak camera that observes a luminescence phenomenon at a synchro scan frequency that is an integer fraction of the repetition frequency, detects the amount of two-dimensional curvature of the streak image due to the sweeping, and determines the shape of the streak image based on the detected amount of curvature. A streak image distortion correction device characterized by correcting distortion. (2) The streak image distortion correction device according to claim 1, wherein the amount of two-dimensional curvature of the streak image is detected from a streak image formed by continuous spot light. (3) The amount of two-dimensional bending of the streak image is detected from the electron trajectory calculated from the amplitude and phase shift of the deflection voltage and the deflection sensitivity of the streak camera. The streak image distortion correction device described in 2. (4) The streak image distortion according to claim 1, wherein the streak image distortion correction is performed by moving data on a frame memory in a predetermined direction according to the detected amount of curvature. correction device.