JPH04157425A - Manufacture of space light modulator - Google Patents

Abstract

PURPOSE:To obtain the wave front required as a space light modulator by assembling a pair of substrates after applying specific ultraviolet-ray-set resin while using a relief printing. method, hardening the resin while radiating ultraviolet rays and forming clearance between the substrates for holding ferroelectric liquid crystal therebetween. CONSTITUTION:Glass substrates, both surfaces of which are polished to a parallel plane degree of a fourth wave length or less and whose thickness is 10% or more of an effective opening diameter, are used for a pair of substrates 11a and 11b. In order to make the periphery of the substrates adhere with the clearance between the substrates controlled, first of all, ultraviolet-ray-set resin of about 15000 centipoise to which silica balls of 3weight% to the resin are mixed and stirred, are applied on the orientation film layer 13a of the substrate 11a using a relief printing method. Clearance between a pair of substrates for holding ferroelectric liquid crystal therebetween is formed by assembling a pair of substrates 11a and 11b, pressing them until the specified clearance is obtained and hardening ultraviolet-set-ray resin by radiating ultraviolet rays leaving them pressed without dispersing spacer particles for controlling the clearance to the inner surface of an opening. By this constitution, an element which has uniform orientation over the whole surface of the opening and whose wave front aberration is small is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a liquid crystal spatial light modulator used in optical information processing, optical computing, machine vision, display terminals, and the like.

[Summary of the Invention] This invention provides a method for manufacturing a liquid crystal element using a ferroelectric liquid crystal composition used in optical information processing, optical computing, machine vision, display terminals, etc. When using glass substrates with a thickness of 10% or more of the effective aperture diameter and polished to a parallel flatness of less than a quarter wavelength, when bonding the substrates together, the gap is reduced without dispersing spacer particles within the aperture surface. silica spheres or resin spheres with an average diameter equal to the aim value of or glass fibers with an average diameter equal to the aim value of the gap,
An ultraviolet curing resin of 1000 centipoise or more mixed with 1 to 10% by weight of O to the resin and stirred was applied by printing using a letterpress printing method, a pair of substrates were assembled, and ultraviolet rays were irradiated while pressurized. By curing the ultraviolet curable resin, a gap was formed to sandwich the ferroelectric liquid crystal.

[Prior Art] Conventionally, in a method for manufacturing a liquid crystal spatial light modulator using a ferroelectric liquid crystal composition used for optical information processing, optical computing, machine vigilance, display terminals, etc.,
As shown in FIG. 3, spacer particles were dispersed within the opening surface, a thermosetting resin was applied by screen printing, and then heat was applied while pressurizing to control and form the gaps.

[Problem H to be solved by the invention] However, in the conventional method, since the spacer particles are dispersed within the aperture plane, the spacer itself becomes a drawback, and the ferroelectric liquid crystal molecules and layers near the particles are affected. Or, because the resin is applied using the screen printing method, the surface structure of the alignment film layer may be destroyed by contact with the screen plate, resulting in alignment defects.Also, since the resin is applied using the screen printing method, the surface structure of the alignment film layer may be destroyed due to contact with the screen plate, resulting in alignment defects. If a glass substrate with less than 10% of the effective aperture diameter is used, it is very time consuming and increases the number of man-hours and costs. There were many problems, such as the glass substrate deforming due to the film formation being unable to withstand the stress, and the wavefront precision required for a spatial light modulator not being achieved.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a liquid crystal spatial light modulator using ferroelectric liquid crystal as a pair of substrates, both sides of which are parallel and flat at a quarter wavelength. When using glass substrates polished as follows and having a thickness of 10% or more of the effective aperture diameter and bonding the periphery of the substrates by controlling the gap between the substrates, spacer particles are added within the aperture surface to control the gap. Silica spheres or resin spheres with an average particle diameter equal to the target value of the gap or glass fibers with an average diameter equal to the target value of the gap are mixed into the resin at 0°1 to 10% by weight without dispersion. Stirred UV curable resin of 1000 centipoise or more is applied by printing using letterpress printing, then a pair of substrates are assembled, pressure is applied until a predetermined gap is created, and UV rays are irradiated while the pressure is applied to coat the UV curable resin. Manufactured using a curing process.

[Example] The contents of the present invention will be explained in detail below using the drawings.

FIG. 1 is a flowchart showing the manufacturing process of a liquid crystal spatial light modulator according to the present invention. As shown in FIG. There are differences in whether the resin is applied by the letterpress printing method or by the letterpress printing method, and the method of pressure bonding. Further, in the manufacturing process of the liquid crystal spatial light modulator according to the present invention, a glass substrate having a thickness of 10% or more of the effective aperture diameter and polished on both sides to a parallel flatness of 1/4 wavelength or less is used. .

Examples will be described below along with the manufacturing process, and differences and advantages from conventional methods will be explained.

FIG. 2 is a conceptual diagram of a liquid crystal spatial light modulator according to the present invention. As the substrates 11a and 11b for sandwiching the liquid crystal molecules, transparent glass substrates having a thickness of 10% or more of the effective aperture diameter and polished on both sides to a parallel flatness of 1/4 wavelength or less were used. The effective opening diameter in this example is 25 mm,
Tempax glass with a thickness of 4 mm was used as the substrate. ITO transparent electrode layers 12a and 12b were provided on the surfaces of both substrates. In addition, the surface of both substrates has an 85mm radius from the normal direction of the substrates.
Alignment film layers 13a and 13b were provided in which silicon monoxide was obliquely vapor-deposited at an incident angle of .degree. and so that the incident directions on the write side and read side substrates coincided in the combined state. On the transparent electrode layer 12a on the writing side by light, an amorphous solicon photoconductive layer 15 was formed by discharging and decomposing a gas mainly composed of 5iFn to form an a-3i:H layer with a thickness of 3 μm. . Further, a dielectric mirror 16 was formed on the film.

Here, as the substrates 11a and 11b, the effective opening diameter is 1
The significance and merits of using a transparent glass substrate having a thickness of 0% or more and polished on both sides to a parallel flatness of 1/4 wavelength or less will be explained.

As described above, the ferroelectric liquid crystal spatial light modulator according to the present invention requires the formation of many thin films on the substrate, and therefore the substrate receives strong mechanical stress from the films. Therefore, the substrate must have sufficient mechanical strength to withstand the mechanical stress from the membrane. Furthermore, since the device is applied as a spatial light modulator in fields such as optical information processing, it must maintain sufficient wavefront accuracy. In the manufacturing method of the present invention, the substrate 11a
, 11b, by using a transparent glass substrate having a thickness of 10% or more of the effective aperture diameter and polished on both sides to a parallel flatness of less than a quarter wavelength, the substrate does not deform even if the film is formed as described above. It was small and could maintain sufficient wavefront accuracy.

Next, the gap between the substrates was controlled and the periphery was bonded together. First, 1.
Silica spheres with an average particle size of 0 μm are mixed in at 3% by weight with respect to the resin and stirred, and the viscosity at room temperature is approximately 15.
000 centipoise ultraviolet curable resin (#3030 manufactured by Three Bond) was applied by printing using a letterpress printing method. After that, the pair of substrates 11a and llb are assembled without dispersing spacer particles for controlling the gap within the opening surface, pressure is applied until a predetermined gap is achieved, and ultraviolet rays are irradiated while the pressure is applied. By curing the cured resin, a gap was formed to sandwich the ferroelectric liquid crystal.

The encapsulated ferroelectric liquid crystal composition was 5CE-6 (B
(manufactured by DH) was used.

Here, there are differences in the process from the conventional method, such as whether or not there is a step of dispersing spacer particles within the opening surface, and whether the resin is applied using a screen printing method or a letterpress printing method. We will explain the advantages of the different crimping methods.

In the spatial light modulator according to the present invention, the resolution is 1
001 p/mm or more, and even a spacer with a diameter of about 1 μm becomes a drawback. In the conventional method, spacer particles are dispersed within the aperture surface, which causes defects in the spacer itself and also affects the ferroelectric liquid crystal molecules and layers near the particles, or causes defects in the resin by screen printing. to apply the orientation lI! by contact with the screen plate. The surface structure of the layer is destroyed, resulting in orientation defects.
Or, since it is heated while pressurizing, it takes a very long time from heating to cooling, which increases the number of man-hours and costs.
However, by adopting the manufacturing process according to the present invention, the spacer particles are not dispersed within the opening surface, so defects caused by the spacer itself and orientation defects caused by the spacer particles are caused. Moreover, since the resin was applied by letterpress printing, the surface structure of the alignment film layer within the opening plane was not destroyed, and uniform alignment could be obtained over the entire surface. Furthermore, by forming gaps by irradiating ultraviolet rays while applying pressure, the time required for heating and cooling is not only possible, but also by irradiating monochromatic light. By observing the reflected light, we were able to monitor the distribution of cell thickness, and it was possible to form a device with accurate cell thickness.

The above-described ferroelectric liquid crystal spatial light modulator is brought into a stable state in which the ferroelectric liquid crystal molecules are uniaxially aligned when viewed from the substrate surface by applying a DC electric field from the outside between the transparent electrodes of both substrates. Furthermore, by reversing the polarity of the applied electric field, a stable state is achieved in which the other ferroelectric liquid crystal molecules are uniaxially aligned when viewed from the substrate surface. This reversal between the two states due to the electric field has nonlinearity and a clear threshold with respect to the electric field applied to the ferroelectric liquid crystal layer. The angle between the two stable states corresponds to the cone angle of the ferroelectric liquid crystal, and in this example, the optical axis is 22.5° from the oblique deposition direction of silicon monoxide (
One of the six stable states with an angle of 45 degrees between the optical axes was set so that the optical axis of the ferroelectric liquid crystal molecules and the polarization axis of the polarizing plate coincided, so the other was The optical axis of the dielectric liquid crystal molecules and the polarization axis of the polarizing plate have an angle of 45''.

Therefore, in a stable state where the optical axis of the ferroelectric liquid crystal molecules and the polarization axis of the polarizing plate match, the incident light is reflected by the ferroelectric liquid crystal layer without any modulation and is blocked by the analyzer. It becomes dark. In addition, in a stable state where the optical axis of the ferroelectric liquid crystal molecules and the polarization axis of the polarizing plate are at an angle of 45″′, the incident light is modulated within the ferroelectric liquid crystal layer, and the phase difference φ=2π・Δ
It comes out as n・2d/λ. At this time, the reflected light becomes bright without being completely blocked by the analyzer.

According to the above-described ferroelectric liquid crystal spatial light modulator, due to the bistability of the ferroelectric liquid crystal element, after erasing by applying an erase electric field, the voltage divided across the liquid crystal layer in the opposite direction to the erase electric field is While applying an electric field such that the photoconductive layer is below the dark value when it is dark and above the dark value when it is bright, an optical image is irradiated with writing light 20 from the outer surface of the cell, or a polygon mirror or galvano mirror is modulated while a semiconductor laser is modulated. By performing scanning using the ferroelectric liquid crystal layer 14, the liquid crystal molecules are inverted only in the area irradiated with light, and this is maintained stably, so that an image can be written and formed on the ferroelectric liquid crystal layer 14. was completed. Further, the image formed by writing can be read out by irradiation with the projection light 21.

The ferroelectric liquid crystal spatial light modulator manufactured by the method according to the present invention has uniform alignment over the entire aperture surface, has no defects due to in-plane spacers, and is an element with small wavefront aberration, which can be used for optical information processing, etc. It was found to be very useful for applications.

[Effects of the Invention] As described above, by the manufacturing method according to the present invention, it is possible to reduce the man-hours and cost of the ferroelectric liquid crystal spatial light modulator, and the manufacturing method according to the present invention can reduce the manufacturing cost. Dielectric liquid crystal spatial light modulators have uniform alignment over the entire aperture surface, do not have the drawbacks of in-plane spacers, and are devices with small wavefront aberrations, making them ideal for optical information processing, optical computing, machine vision, and display terminals. It is very useful for applications such as

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the manufacturing process of a ferroelectric liquid crystal spatial light modulator according to the present invention. FIG. 2 is a sectional view showing the structure of a ferroelectric liquid crystal spatial light modulator according to the present invention, and FIG. 3 is a flowchart showing a conventional manufacturing process. 11a, llb...Transparent substrates 12a, 12b...Transparent electrodes 13a, 13b...Alignment film 14...Ferroelectric liquid crystal layer 15...Photoconductive film 16...Dielectric mirror 20...・Writing light 21...Reading light Fig. 1 Fig. 3

Claims (1)

[Claims] A photoconductive layer and a dielectric multilayer film mirror are provided on one electrode between a pair of substrates having electrodes, and the film serves as a film for orienting liquid crystal molecules on both substrates at an angle of 75° to the normal direction of the substrates.
Silicon monoxide was obliquely vapor-deposited at an angle of 85 degrees from In the method for manufacturing a liquid crystal element, as a pair of substrates,
Using a glass substrate with a thickness of 10% or more of the effective aperture diameter, both sides of which have been polished to a parallel flatness of less than a quarter wavelength, the gap between the substrates is controlled and the periphery is bonded together. Silica spheres or resin spheres with an average particle size equal to the target gap value or glass fibers with an average diameter equal to the target gap value are applied to the resin without dispersing spacer particles to control the gap. 0.1~1
A UV curable resin of 1000 centipoise or more mixed with 0% by weight and stirred is applied by printing using a letterpress printing method, a pair of substrates are assembled, pressure is applied until a predetermined gap is created, and UV rays are irradiated while the pressure is applied. A method for manufacturing a liquid crystal spatial light modulator, characterized in that a gap for sandwiching a ferroelectric liquid crystal is formed by a step of curing an ultraviolet curable resin.