JPS5864742A - Space modulating device - Google Patents

Abstract

PURPOSE:To enable removal of written electric-charge images or rewriting of electric-charge images by installing between a crystalline plate and an electron- image producing means, a secondary-electron catching electrode which is located so that it doesn't prevent any electric-charge image from being formed on the mirror surface of the crystalline plate, and a power source which can change a power source used for the electrode of the crystalline plate. CONSTITUTION:In an airtight glass case, a photoelectric screen 5, a focusing electrode 6, a micro-channel plate MCP7, a secondary-electron cathcing electrode 8 and an electrooptic crystalline plate 9 are arranged in that order. The electrode 8 and the plate 9 are placed parallel to each other so that they are spaced at a distance of, for example, 0.5mm.. The front surface of the plate 9 is provided with a transparent crystalline plate electrode 91. A power source (D) works as a power source for the electrode 8. Power sources (E-G), which are the elements of a crystalline-plate-electrode-power source, are used for determining the electric potential of the electrode 91 of the crystalline plate 9, and connected to the electrode 91 by the change-over-operation of a switch 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spatial modulation device using an electro-optic crystal plate.

A spatial light modulation device (hereinafter referred to as M 8 L M) using a microchannel plate used as a recording medium is 1
976, SPIg, Vol. 177, pp. 67-70, in an article by Ward et al. First, the principle and operation of this M8LM will be briefly described.

FIG. 1 is a schematic diagram showing the configuration of the MSLM.

The photocathode 22 of this device, the microchannel plate (
It basically comprises an MCP (MCP) 24 and an electro-optic crystal plate 28, which are enclosed in a vacuum container having an entrance window 2 and an exit window. 23 and 25 are the MCP person and output electrode, respectively. The front surface of the electro-optic crystal plate 28 forms a dielectric interface 27, and the rear surface is provided with a transparent electrode 4. The dielectric interface 27 of the electro-optic crystal plate 28 has a very high resistance over the entire surface.

When the writing light a enters the photocathode n and an electronic image is formed, the electronic image is amplified by the MCP 24. The amplified electron image is then made incident on the dielectric mirror surface 27.

The resulting surface charge distribution causes spatial variations in the refractive index within the electro-optic crystal plate. The writing light projected from the lower left is reflected by the semitransparent mirror 31, reaches the electro-optic crystal, is reflected by the dielectric interface 27, and is returned.

Since the refractive index of the electro-optic crystal plate 28 depends on the surface charge image, the reflected light d undergoes phase or intensity modulation.

M#8LM according to the above configuration is suitable for storing charge images for a long time, but there seems to be some problems in erasing charge images for reuse. .

The main purpose of the present invention is to be able to select many modes of use;
The object of the present invention is to provide a spatial modulation device that erases a written charge image or forms a constant and uniform charge distribution state to enable rewriting.

In order to achieve the above main object, the spatial modulation device according to the present invention includes an electron image generating means and an electro-optic crystal plate, and forms a charge image on a mirror surface of the hypochondral optical crystal plate by electrons from the electron image generating source. In a spatial modulation device using a radiation image conversion tube that changes the two-dimensional distribution of refractive index within the crystal plate by an electric field between the charge image and a transparent electrode provided on the other surface, the crystal plate and the electron image are A secondary electron collecting electrode is disposed between the generating means so as not to impede the formation of a charge image on the boundary surface, and is for collecting secondary electrons generated on the burning surface, and a collection electrode power source for supplying a collection voltage; a first voltage applied to the transparent electrode to make the secondary electron emission ratio of the mirror surface larger than 1; and a second voltage applied to the transparent electrode to make the emission ratio substantially 1. The crystal plate electrode power supply is provided with a crystal plate electrode power supply that can switch and connect the voltage or a crystal plate electrode power supply that can switch and connect the second voltage and the third voltage for making the emission ratio smaller than 1.

The spatial modulation device according to the present invention will be described in more detail below with reference to the drawings and the like.

FIG. 2 is a diagram showing an embodiment of the spatial modulation device according to the present invention. In the figure, 1 is a subject, 2 is an objective lens, and 3 is an optical image of the subject formed by an objective lens Z.

Reference numeral 4 denotes the entire optical image conversion tube including the glass airtight container and the structure built into the container. Inside the container, a photocathode 5, a focusing electrode 6, a microchannel plate (hereinafter referred to as MCP) 7, a secondary electron collecting electrode 8, and an electro-optic crystal plate 9 are arranged in this order.

The collection electrode 8 is a copper mesh having a grid spacing of 30 lines/square and an aperture ratio of 604.

The collection electrode 8 is arranged parallel to the electro-optic crystal plate 9 with a distance of 0.5M.

The rear end of the container serves as an information extraction window.

An input electrode 71, which is an electrode on the electron incident side of the MCP, is provided on the front surface of the MCP 7, and an output electrode n, which is an electrode on the electron output side, is provided on the rear surface. As the electro-optic crystal plate 9, for example, L t NbO5 crystal or LiTa0a crystal can be used. - The front surface of this crystal 9 is finished to a mirror surface and will hereinafter be referred to as a mirror surface 92. Further, an FiS transparent crystal plate electrode 91 is provided on the rear surface of the crystal plate 9.

In this embodiment, a photocathode is used, but in the case of an image source that can directly excite the MCP 7, such as X-rays, the photocathode is no longer an essential component. M.C.
It should be understood that the configuration before P is an embodiment of the electronic wave generation means.

A-B-C-D-B-F-G are power sources,
Power supply A provides the bias voltage between the photocathode 5 and the focusing electrode 6, power supply B provides the voltage between the focusing electrode 6 and the input side electrode 71 of the MCP, and power supply C provides the bias voltage of the MCP 7.

In the device of this embodiment, these power supplies keep the photocathode 6 at -4.0 KV with respect to the reference potential (Ov) of the electrode on the emission side of the MCP. Similarly, the focusing electrode is -3.7 KV, and the electrode 71 in the MCP incident example is -LOK.
It is maintained at V.

The power source constitutes the power source of the secondary electron collecting electrode 8, and the secondary electron collecting electrode 8 is connected to the 4. It is maintained at OKV.

Power sources E-F-G are connected to electrodes 91 of the electro-optic crystal plate 9, respectively.
This is the power source for determining the potential of the crystal plate electrode. By switching the switch 15, it is connected to the electrode 91, and when connected to the electrode 15a, it is 0. IKV, 15
A voltage of 4 KV is supplied to the electrode 91 when the electrode is connected to the electrode 91, and a voltage of 8 KV is supplied to the electrode 91 when the electrode is connected to the electrode 91.

Semi-transparent mirror 10, monochromatic filter 11, collimator lens 1
2, a point light source 13, and a photographic film 14 are devices for reading.

If a laser light source is used as the light source 13, an optical image using coherent light can be obtained. This optical image can be used for image calculations.

Figure 3 shows the mirror dry secondary electron emission ratio δ of the electro-optic crystal plate 9.
This is a graph showing the accelerating voltage of incident electrons on the horizontal axis.

In this embodiment, the acceleration voltage is applied to the output electrode of MCP 7 and the mirror surface 9.
The potential of the mirror surface 92 is approximately equal to the potential of the transparent electrode 91 when no charge exists on the surface.

As shown in FIG. 3, when the acceleration voltage is 0. El lower than IKV
Below, δ<1, between El and E2 (='4KV), δ>1, and beyond E, δ<1.

In the present invention, the change in the sign of δ before and after E2 is utilized to form and erase a charge image or to form a uniform charge distribution state.

The operating modes of the device according to the present invention can be broadly classified into the following I, I, and 11N modes. FIG. 4 shows the operation mode of the 1% N in comparison with the secondary electron emission ratio shown in FIG.

FIG. 5 shows similar operation modes (1) and (2). In each figure, the vertical axis indicates the potential of the mirror surface 92, e
(o), ! ((1))e←) indicates the absence of charge, the presence of positive charge, and the presence of negative charge, respectively. Also, Wr is writing,
Er means erase and Pr means preparation.

In addition, the images drawn in each figure are each assumed to have a special shape, and are schematically illustrated with only the one-dimensional direction of the two-dimensional image as the horizontal axis.

(I) First, the first operation mode will be explained (see FIG. 4).

In this mode, when writing Wr, switch 15 is set to contact 15m.
and set the voltage of the transparent electrode 91 of the electro-optic crystal plate 9 to 0.
I KV. An image of the subject 1 is formed on the photoelectric image 5 by the writing light from the subject 1. The photoelectrically converted electron image is multiplied by the MCP 7, and the multiplied electrons are made to enter the electro-optic crystal plate 9. As a result, a positive charge image e(+) is formed on the mirror surface 92 of the electro-optic crystal plate 9.

Since there is no electric charge initially on the mirror surface 92 of the electro-optic crystal plate 9, it is maintained at approximately the same potential as the transparent electrode 91, ie, 0.1 KV. In other words, the potential of the mirror surface 92 is the output voltage of the MCP7.
72yoshi0. Since the IKV is high, the secondary electron emission ratio δ is δ>1 as shown on the left side of FIG. Therefore, it is positively charged depending on the amount of primary electrons incident on this surface.

The emitted secondary electrons have a higher potential than the mirror surface 92 = 4KV
The secondary electron collecting electrode 8 collects the electrons.

The switch 15 is also connected to the contact 15a during reading (Wr). The light from the point light source 13 passes through the collimator lens 1
2 makes it parallel light.

Then, the filter 11 converts the image into a monochromatic color. This monochromatic parallel light is modulated by an electro-optic crystal plate 9. In other words, since the electro-optic crystal plate 9 is a positively charged image on the mirror surface 92 of the monochromatic parallel light, and the optical path length in the crystal is changing, there are parts where it is strengthened and parts where it is weakened due to interference, resulting in an optical image. A corresponding modulation is performed.

The modulated light is reflected by a semi-transparent mirror 10 and transferred to a photographic film 1.
When erasing (F'r) recorded on 4, connect switch 15 to 15b L
, set the electrode 91 to 4KV. Using a light source for erasing (not shown), the entire surface 5 is irradiated with light of uniform intensity. The uniformly distributed electrons obtained by photoelectric conversion are MC
At P7, the light is multiplied and enters the electro-optic crystal plate 9, and the charge on the mirror surface ψ is reduced to 0, thereby completing erasing.

As described above, the potential of the transparent electrode on the mirror surface of the electro-optic crystal plate 9 is 4 KV plus a potential increase due to positive charging. Therefore, since the potential of the mirror surface 92 is higher than E2 (=4 KV) as shown on the left side of FIG. 4, δ of the mirror surface 92 becomes δ×1. Therefore, there is a tendency for negative charges to be added until E2 is reached. When E2 is reached, δ=1 and the charge becomes 0, and the potential of the mirror surface 92 is 4.
It becomes KV.

Next, the second operation mode will be explained (see Fig. 4 (■)).

This mode is executed in the order of preparation, writing, and erasing. In the preparation step, the switch 15 is connected to the contact 15a and the electrode 91 of the electro-optic crystal plate is set to 0. Maintained by IKV. In the writing process, the switch 15 is connected to 15b, and the electrode 91 of the electro-optic crystal plate is connected to 4. Maintained at OKV. Further, in the erasing process, the switch 15 is connected to the contact 15a, and the electrode 9
1 is 0. Maintained by IKV.

During preparation Pr, the entire surface of the photocathode 5 is irradiated with light of uniform intensity. The electron image obtained by photoelectric conversion is multiplied by the MCP 7, and the multiplied electron image is made incident on the electro-optic crystal plate 9. The charge on the mirror surface 92 is positive (e(+-))
Make it.

As described above, the potential of the mirror surface 92 of the electro-optic crystal plate 9 is initially at 0.1 KV.

At this time, since the secondary electron emission ratio δ of the mirror surface 92 is δ>1, the mirror surface 92 of the crystal plate is uniformly positively charged. As a result, the potential of the mirror surface 92 approaches E2 (-4KV), resulting in a uniform positive potential distribution.

During writing (Wr), an image 3 of the subject 1 is projected onto the photocathode 5 . The electronic image obtained by photoelectric conversion is multiplied by the MCP 7 and projected onto the electro-optic crystal plate 9.

Then, an inverted image is formed in the positive charge on the mirror surface 92. That is, writing is performed on the electro-optic crystal plate 9 in the preparation process described above.
The mirror surface starts from a point that is uniformly positively charged in advance.

The mirror surface 92 of the electro-optic crystal plate 9 has a potential of approximately 4 KV (approximately 4 KV) given by the electrode 91 at the time of writing, plus the potential increase due to the positive charge e(+) (Ez = close to 4 KV).
KV+E2=8 KV.

Here, as shown on the left side of FIG. 4, since δ is δ<1, negative charges tend to accumulate depending on the amount of primary electrons incident on the boundary surface 92 corresponding to the optical image. That is, since the uniform positive charge e((1) is overlapped with the negative charge of the distribution corresponding to the image, an inverted image is formed in the positive charge.

Reading (Wr) is no different from the first mode of operation described above.

Erasing (Er) is the same as preparing (P,) in this mode. The boundary surface 92 of the electro-optic crystal plate 9 is 0, IKV-E2
(=4KV) between O (the part where no image is formed is Ex).

Since δ of the mirror surface 92 of the electro-optic crystal plate 9 is δ>1, the mirror surface 92 of the crystal plate tends to be positively charged. As a result, the positive charge increases until the potential of the mirror surface 92 reaches E2, and when it reaches E2, δ=1, which means that the mirror surface 92 is uniformly positively charged and the inverted image is erased.

After erasing is completed, next writing becomes possible.

(1) Next, the third operation mode will be explained (see FIG. 5).

In this operating mode, when writing, switch 15 is connected to contact 15.
The transparent electrode 91 of the electro-optic crystal plate 9 connected to 8. O
KV is maintained. During erasing, switch 15 is contact 1
5c and the transparent electrode 91 is maintained at 4.0KVK.

When an image of the subject 1 is projected onto the photocathode 5 during writing (Wr), an electronic image corresponding to the image is formed by photoelectric conversion.
This image is multiplied by MCP7. The multiplied electron image is made incident on an electro-optic crystal plate 9. As a result, a negative charge image e(-) is formed on the mirror surface 92 of the electro-optic crystal plate 9.

The principle of negative charge image formation is as follows.

The mirror surface 92 of the electro-optic crystal was originally 8.OK as described above.
It is V. Here, as shown on the left side of FIG. 54, the secondary electron emission ratio δ is δ×1.

Therefore, the mirror surface 92 is negatively charged depending on the amount of primary electrons incident on the mirror surface 92.

Reading (Wr) is the same as described above in the first mode.

Erasing (Er) is performed by irradiating the entire photocathode with light of uniform intensity.

The uniform electron flow obtained by photoelectric conversion is multiplied by MCP7.

The multiplied electrons are made incident on the interface value of the electro-optic crystal plate 9 and become ``(0).As a result, the charge on the mirror surface 92 is erased.Before erasing, the mirror surface ψ of the electro-optic crystal plate 9 teeth,
It is in a state in which the potential drop due to the negative charge e (→) is superimposed on 4KV. Since the surface potential of the part where the negative charge e (-) exists is lower than E2, the secondary electron emission ratio δ of the mirror surface 92 is δ>1. Therefore, a positive charge is added until E2 is reached. When E2 is reached, δ=1 and the charge is uniformly erased and becomes e<o>. Next, the fourth operation The mode will be explained (see Figure 5 ■).

In this mode, switch 15 is set to 15c during preparation.
The electrode 91 of the crystal plate connected to is maintained at 8 KV. During writing, switch 15 is connected to 15b and crystal electrode 91 is maintained at 4 KV. During erasing, the switch 15 is connected to 15c and the electrode 91 of the crystal plate is connected to 5KV.
K is maintained.

Preparation (Pr) is started by irradiating the entire surface of the photocathode 5 with light of uniform intensity.

Uniform electrons obtained by photoelectric conversion are multiplied by the MCP 7 and made incident on the crystal plate 9. The mirror surface 92 of the electro-optic crystal plate 9 was originally 8. Since it is near OKV, the secondary electron emission ratio δ is δ×1. Therefore, the mirror surface has a negative charge e (−
) adheres uniformly.

For writing (Wr), the voltage of the electrode 91 of the crystal plate is set to 4. The secondary electron emission ratio δ of the interface 92 is δ〉
1, an inverted image is formed in the negative charge e (-).

Reading is the same as described in the first mode.

For erasing (gr), the voltage of the electrode 91 is set to 8. OKV is applied to bring the mirror surface 92 to the region of δ1, and a negative charge e(→ is uniformly attached to the front surface) As explained in detail above, in the device according to the present invention, a secondary electron collecting electrode is provided, and Since the electrode power source of the electro-optic crystal plate can be switched in various ways, erasing or preparing becomes easy.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of a conventional MSLM, FIG. 2 is a diagram showing an embodiment of the MSLM according to the present invention, FIG. 3 is a graph showing the secondary electron emission characteristics of an electro-optic crystal, and FIG. FIG. 5 is a graph for explaining the w, first and second operation modes of the embodiment device. FIG. 5 is a graph for explaining the third and fourth operation modes of the embodiment device. 1...Subject 2...Objective lens 3...
Optical image 4... Optical image conversion tube 5... Photocathode 6... Focusing electrode 7... Microchannel amplifier v-) (=MCP) 71... Electrode 72 on the electron incident side of MCP... Electrode 8 on the electron emission side of MCP...Secondary electron collecting electrode 9...Electro-optic crystal plate 91...Electrode 92 of the electro-optic crystal plate...Mirror surface 10 of the electro-optic crystal plate...・Semi-transparent mirror 11... Single color filter 1
2... Collimator lens 7... Point light source 14... Photographic film 15.
...Selector switch 21...Incidence window 22...Photocathode prisoner...! vicP input electrode...MC
P 25...MCP output electrode...gap 27...dielectric mirror surface Yu...electro-optic crystal IL29...transparent electrode device...exit window 3
1... Semi-transparent mirror A to G... Power source 1 Figure 72 Figure 3 Figure 5 (I[[) (X2I)

Claims (6)

[Claims] (1) It includes an electron image generating means and an electro-optic crystal plate, and forms a charge image on a mirror surface of the electro-optic crystal plate by electrons from the electron image generation source, and is provided on the other surface from the charge image. In a spatial modulation device using a radiation image conversion tube that changes the two-dimensional distribution of refractive index within a crystal plate by an electric field between transparent electrodes, a charge image is formed on a mirror surface between the crystal plate and an electron image generating means. a secondary electron collection electrode that is arranged so as not to impede formation and that collects secondary electrons generated on the mirror surface; a collection electrode power source that supplies a collection voltage to the collection electrode;
A crystal plate electrode power supply capable of switching and connecting a first voltage for increasing the secondary electron emission ratio of the specular surface to more than 1 and a second voltage for making the emission ratio substantially 1 to the transparent electrode. A spatial modulation device characterized by comprising: (2) A first voltage is connected to the crystal plate electrode power supply to form a positive charge image for writing, and a second voltage is connected to the crystal plate mirror surface with a uniform electron flow. The spatial modulation device according to claim 1, which is configured to perform erasing by irradiation. (3) Using the crystal plate electrode power supply, connect the first voltage and irradiate the mirror surface of the crystal plate with a uniform electron flow to uniformly form positive charges and prepare the second voltage. The spatial modulation device according to claim 1, wherein a voltage is connected to perform writing to form an inverted image in a positive charge, and a first voltage is connected to perform erasing corresponding to the preparation. . (4) comprising an electron image generating means and an electro-optic crystal plate, a charge image is formed on a mirror surface of the electro-optic crystal plate by electrons from the electron image generation source, and the charge image is provided on the other surface of the electro-optic crystal plate; In a spatial modulation device using a radiation image conversion tube that changes the two-dimensional distribution of refractive index within a crystal plate by an electric field between transparent electrodes, a charge image is formed on a mirror surface between the crystal plate and an electron image generating means. a secondary electron collection electrode for collecting secondary electrons generated on the mirror surface, which is arranged so as not to interfere with the mirror surface; a collection electrode power source that supplies a collection voltage to the collection electrode; A crystal plate electrode power source is provided which can switch and connect a second voltage to make the secondary electron emission ratio of the mirror surface substantially 1, and a third voltage to make the emission ratio smaller than 1. A space transformation device characterized by: (5) A patent claim configured such that a third voltage is connected to the crystal plate electrode power source to form a negative charge image for writing, and a second voltage is connected to erase the negative charge image. 4. The spatial modulation device according to item 4. (6) Prepare by connecting a third voltage using the crystal plate electrode power source to form a uniform negative charge on the crystal plate with a uniform electron flow, and connect a 20th voltage to form a uniform negative charge on the crystal plate. 5. The spatial modulation device according to claim 4, wherein the spatial modulation device is configured to form an inverted image in a negative charge and perform erasing by connecting a third voltage.