JPH0441936B2 - - Google Patents

Description

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 streak camera device that corrects two-dimensional bending of a streak image of measured light due to a repeated light emission phenomenon. The present invention relates to a distortion correction device.

[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, an optical phenomenon is displayed on a fluorescent surface by a circular scan streak camera 12, which is scanned by a high-sensitivity television camera 13 and converted into an electrical signal, which is analyzed and processed by an image processing device 15. There is.

Figure 4 is a diagram showing the streak tube of the circular scan method in Figure 3, Figure 5 is a diagram showing the deflection voltage waveform of the streak tube, Figure A is a diagram showing the vertical deflection voltage waveform, Figure B is a diagram showing the vertical deflection voltage waveform. FIG. 6 is a diagram showing the horizontal deflection voltage waveform, FIG. 6 is a diagram showing the photoelectron arrival point on the fluorescent surface and its extension surface in elliptical sweep, and FIG. 7 is a diagram showing the case where repeated optical phenomena are observed by elliptical sweep. Figure A is a repetitive light emission waveform diagram, Figure B is a deflection voltage waveform diagram, and Figure C is a diagram showing a streak image. In the figure, 21 is a photocathode, 22 is a mesh electrode, 23 and 24 are focusing electrodes, 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 E ₁ ,
E ₂ is a power source, R is a resistor, and P ₁ to _{P 10} and P ₁ ′ to _{P 10} ′ are photoelectron arrival points.

Next, to explain the operation, the light to be measured is converted into photoelectrons by the photocathode 21, and the light to be measured is converted into photoelectrons by the mesh electrode 22.
is accelerated by The focusing electrodes 23 and 24 form an electron lens that focuses the photoelectrons generated at the photocathode 21 onto the fluorescent surface 27. The photoelectrons accelerated by the mesh electrode 22 are focused through the electron lens, and the photoelectrons are focused on the 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. The vertical deflection electrode 25a and the horizontal deflection electrode 25b each have a sine wave deflection voltage generating circuit 2.
6a and 26b apply sinusoidal voltages V _a and V _b as shown in FIGS. 5A and 5B. For example, the voltage applied to the vertical deflection electrode 25a is V ₁ p-
The voltage applied to the horizontal deflection electrode 25b is a sine wave voltage of V ₂ pp on which a bias voltage of approximately V ₂ /2 is superimposed, and these voltages V _a , V _b is shifted in phase by π/2. Therefore, the voltages V _a and V _b are applied to the deflection electrodes 25a,
25b, an elliptical sweep with the center shifted in the horizontal direction by a bias voltage of V ₂ /2 is performed, and by appropriately selecting the values of V _a and V _b , for example, at times t=t ₁ , t The photoelectron incident on ₂ ...t ₉ is
As shown in FIG. 6, points P ₁ , P _{2 ,} .

In addition, a vertical deflection voltage 25a, a horizontal deflection electrode 25
The frequency of the sine wave voltage applied to b is set to an integer fraction 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 voltages 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 luminance (energy), as shown from point P ₅ to point P ₉ in Figure 6,
The phenomenon during the return sweep can be removed from the output phosphor surface 27.

Next, for example, if the repeated optical phenomenon as shown in FIG. 7A is swept with a voltage waveform as shown in FIG. 7B,
As shown in Figure C, a streak image is formed on the fluorescent surface 27. At this time, streak images P ₁ to _{P 4} of the optical phenomenon from t=T ₀ to t=T ₁ are formed on the fluorescent surface 27.
However, streak images P ₅ to _{P 10} of the light phenomenon from t=T ₁ to t=T ₂ are not formed on the fluorescent surface. Therefore, long-time phenomena and optical phenomena whose repetition frequency is higher than the sweep frequency can be prevented from overlapping on the fluorescent surface, thereby preventing double exposure. Also, from t=T ₀ ' to t=
The streak images P ₁ ′ to _{P 4} ′ of the optical phenomenon up to T ₁ ′ are superimposed on the same positions as P ₁ to _{P 4} , respectively, and energy is accumulated on the fluorescent surface.

FIG. 8 is a diagram for explaining how streak images are read out and stored by a TV camera in a conventional optical measuring device, and 28 in the figure 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 converted to an A/D converter (not shown). The data is quantized and stored in a large-capacity digital memory 28 (hereinafter referred to as frame memory). frame memory 2
8 is a two-dimensional memory having N×N pixels, which 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 frame memory,
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 0i,j<N, and the luminance value recorded in pixel (i,j) is expressed as I(i,j).
As shown in FIG. 9, i is the horizontal axis of the frame memory and corresponds to the horizontal axis on the fluorescent surface, and j is the vertical axis of the frame memory and corresponds to the time axis of the streak image.

Here, as shown in Figure 10, a certain area
AV (i ₀ , i ₁ ) and AH (j ₀ , j ₁ ) are defined as follows.

AV (i ₀ , i ₁ ) = {(i, j) | i ₀ ii ₁ , 0j<
N} AH(j ₀ , j ₁ )={(i, j) | 0i<N, j ₀ j
j ₁ } Also, as shown in FIG. 11, information IV (i ₀ , i ₁ , j) and IH (j ₀ , j ₁ , i) regarding luminance are defined as follows.

IV (i ₀ , i ₁ , j) = _i1 〓 ⁱ⁼ⁱ⁰ I (i, j), 0j<N IH (j ₀ , j ₁ , i) = _j1 〓 ^j=j0 I (i, j), 0i <N As shown in Figure 11, IV (i ₀ , i ₁ , j) is AV
(i ₀ , i ₁ ) for each j from i=i ₀ to i
= i ₁ , IH (j ₀ , j ₁ , i) is AH
(j ₀ , j ₁ ) for each i from j = j ₀ to j
=j is integrated up to ₁ . That is, in the vertical direction, the integral value of the luminance from i ₀ to i ₁ for each scanning line is determined as IV, and
Also, in the horizontal direction, assume a vertical line as a scanning line,
Let IH be the integral value of the luminance from j ₀ to j ₁ along this vertical line, obtained for each vertical scanning line.

In the conventional device, IV(i ₀ , i ₁ ,
j), IH(j ₀ , j ₁ , i) and performs these analysis and processing.

[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, and FIG. 13 is a diagram showing a streak image on a frame memory in time spectroscopy.
29 is a pinhole plate, and 30 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 is obtained in the frame memory 28 as shown in FIG.

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, wavelengths λ ₁ , λ ₂ , λ ₃ , ... are time spectrally analyzed. If a streak image with a curve as shown in FIG. 13 is directly analyzed using the IV and IH described above, the wavelength information of IV (i ₀ , i ₁ , j) will differ depending on j, and IH (j ₀ , j ₁ , i) and IH(j ₂ ,
j ₃ , i) will have different wavelength information for the same i. Therefore, if the streak image is directly analyzed using the above-mentioned IV and IH, it is difficult, for example, to compare changes over time for each wavelength or to compare changes in wavelength for each time.

The present invention is intended to solve the above-mentioned problems, and is a streak camera that corrects the streak image distortion of the light to be measured and facilitates the analysis of the streak image when repeatedly observing optical phenomena using a streak camera. An object of the present invention is to provide an 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 repeated light emission phenomena at a synchro scan frequency that is an integer fraction of the repetition frequency, the streak camera having a two-dimensional bending of the streak image due to the sweeping from the streak image or the electron trajectory. The present invention is characterized by comprising a detection means for detecting the amount of bending, and a correcting means for correcting the amount of bending by operating data on the melimo according to the detected amount of bending.

[Effect]

The streak image distortion correction device of the present invention uses a streak camera to observe a repeated light emission phenomenon at a synchro scan frequency that is an integer fraction of the repetition frequency. The two-dimensional bending of the streak image caused by applying and sweeping the sinusoidal voltages as the deflection voltages of the orthogonal deflection axes is detected, and the distortion of the streak image is corrected based on the amount of the detected bending, and the streak image is created. To facilitate the analysis of

〔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 a group of photoelectrons from the photocathode 33 enters the vertical deflection electrode 25a at t= _t0 , the group of photoelectrons enters the vertical deflection electrode 25a, the horizontal It is deflected by the deflection electrode 25b and moved in parallel to the output fluorescent surface 27 by T _V (t ₀ ) in the vertical direction and T _H (t ₀ ) in the horizontal direction compared to the case where nothing was deflected. be projected. In this way, when the slit of the input optical system of the streak camera opens horizontally, information in the lateral direction of the slit is also projected onto the horizontal axis x on the fluorescent surface. If y is the spatial axis in the vertical direction of the fluorescent surface and s(y) is the amount of horizontal shift on the fluorescent surface, then if s(y) is known, an image can be created based on s(y). It becomes possible to perform the conversion and correct the curvature of the streak image. This horizontal shift amount can be determined as follows.

The first method involves replacing the slit in Figure 1 with a pinhole, injecting continuous light, sweeping the ellipse as described above, and transmitting the image accumulated on the fluorescent surface to a high-sensitivity TV.
It is read out by the camera and stored in the frame memory. The image stored in the frame memory at this time is shown in FIG.

In the streak image shown in Figure 2, for each j < N, find IH (j, j, i), and calculate IH (j, j, i).
Let i be MAX be m(j). That is, IH (j, j, m (j)) > IH (j, j, i) for all0
i<N This m(j) represents the abscissa coordinate i where the streak image is stored, and the shift amount ss(j) is defined as ss(j)=m(j)-m(N/2) Then, if ss(j) is obtained by applying the least squares method to an n-th degree polynomial, then s(j) is
s(j) is an arbitrary j for the storage position of the streak image at j=N/2, as shown in FIG.
This represents the horizontal shift amount of the streak image storage position in .

The second method is to calculate the electron trajectory in the streak tube from the amplitude and phase shift of the sinusoidal deflection voltage applied to the vertical deflection electrode 25a and the horizontal deflection electrode 25b, and the deflection sensitivity of the streak tube. The trajectory is calculated and the horizontal deflection amount s(j) is determined.

Streak image I recorded in frame memory
(i, j) is an axis shifted from I(i, N/2) by s(j) for each j with respect to information on the horizontal axis of the slit. For example, in the case of time-resolved spectroscopy, the horizontal axis of the slit is the wavelength axis, but each (i,
If the wavelength information corresponding to j) is λ(i, j), then λ(i, j)=λ(i-s(j), N/2) holds true. Therefore, the obtained streak image I(i,j) is converted into I′(i,j)=I(i+s(j),j) and I′(i,j), and the shift amount s(j ) in the horizontal axis direction, a streak image in which the vertical axis direction (equal wavelength line) is balanced with the vertical axis direction (time axis) can be obtained. By finding the shift amount a(j) in the horizontal axis direction, 0j ) for AV,
It determines AH, IV, and IH, and enables extremely high-precision measurement and analysis 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 the data on the frame memory is corrected by moving in a predetermined direction using this amount of curvature, thereby eliminating distortion. Since streak images can be obtained, the method of time-resolved spectroscopy can be performed easily and with high precision even with a circular scan streak camera system, which makes it possible to obtain long-lived fluorescence using time-resolved spectroscopy in the biochemical field. 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 optical communications field.
Great effects can be obtained.

[Brief explanation of the drawing]

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. 4 is a diagram showing the streak tube of the circular scan method in FIG. 3, FIG. 5 is a diagram showing the deflection voltage waveform of the streak tube, and FIG. 4 is a diagram showing the vertical deflection voltage waveform. Figure B shows the horizontal deflection voltage waveform, Figure 6 shows the photoelectron arrival point on the fluorescent surface and its extended surface in elliptical sweep, and Figure 7 shows the case in which repeated optical phenomena are observed by elliptical sweep. Figure A is a repetitive light emission waveform diagram, Figure B is a diagram showing the repeated light emission waveform.
is a deflection voltage waveform diagram, C is a diagram showing a streak image, FIG. 8 is a diagram for explaining how a TV camera reads out and stores a streak image in a conventional optical measuring device, FIG. 10 is a diagram showing a frame memory, FIG. 11 is a diagram showing a streak image stored in the frame memory, and FIG. 12 is a diagram showing a streak image stored in the frame memory.
FIG. 13, a diagram for explaining the bending of a streak image by a conventional circular scan streak system, is a diagram showing a streak image on a frame memory in time spectroscopy. 11... Emitted 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
...Focusing electrode, 25a...Vertical deflection electrode, 25b
... Horizontal deflection electrode, 26a, 26b ... Sine wave deflection voltage generation circuit, 27 ... Fluorescent surface, E ₁ , E ₂ ...
Power supply, R...Resistance, _P1 to _P10 , _P1 ' to _P10 '...Photoelectron arrival point, 28...Frame memory, 29...Pinhole plate, 30...Pinhole, 31...Slit plate , 32...slit, 33... photocathode.

Claims (1)

[Claims] 1. Double exposure due to return sweep is prevented by applying and sweeping sinusoidal voltages having a phase difference of 90 degrees with each other having a bias voltage superimposed on one side as deflection voltages of orthogonal deflection axes. At the same time, the streak camera observes the repeated light emission phenomenon at a synchro scan frequency that is an integer fraction of the repetition frequency, and detects the amount of two-dimensional bending of the streak image due to the sweeping from the streak image or the electron trajectory. A streak image distortion correction device comprising a detection means and a correction means for correcting the amount of curvature by manipulating data on a memory according to the detected amount of curvature. 2. The streak image distortion correction device according to claim 1, wherein the detecting means detects the amount of two-dimensional curvature of a streak image from a streak image obtained by continuous spot-like incident light. 3. The detection means detects the amount of two-dimensional bending of the streak image 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 according to item 1. 4. Claim 1, wherein the correction means corrects the data on the frame memory by moving it in a predetermined direction according to the detected amount of bending.
The streak image distortion correction device described in 2.