JPH03163334A - Light-scattering measuring apparatus - Google Patents

Abstract

PURPOSE:To measure the angular distribution of the intensities of scattered light and transmitted light by forming a parallel light beam whose diameter is small with an optical system by using white-color light source having the continuous distribution in a visible light region and a lens, inputting the parallel light beam into a light scattering material, and scattering the light. CONSTITUTION:A main body 7 includes a white-color light source, a lens system for obtaining a parallel beam, a sample stage for holding a sample such as a liquid crystal element and a detector comprising a photodiode and the like. A controller 8 which is connected to the main body 7 receives the output signal from the detector in the main body 7. The signal is passed through a preamplifier and inputted into a logarithmic amplifier. Thus the logarithmic output is obtained and sent into an X-Y recorder 9. Then, the parallel light beam having the small diameter is formed with the optical system comprising the white-color light source having the continuous distribution in the visible light region and the optical system lens. The parallel light beam is inputted into a light scattering material and scattered. Then, the angular distributions of the scattered light and the transmitted light are measured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a light scattering measurement device used for evaluating optical properties such as light scattering, and is useful for evaluating light scattering properties of liquid crystal display elements, etc. related to equipment.

One of the objects of the above measurement is a liquid crystal display element, which, like an optical shutter, can selectively control and change the light transmittance of the element's liquid crystal by applying an electric or magnetic field. This is what has become.

Examples include French Patent No. 2;139.537, U.S. Pat. No. 4,435,047 and U.S. Pat.
No. 71,618, a method is shown in which a nematic liquid crystal material is encapsulated as a number of droplets in a matrix of transparent encapsulant material and an electric or magnetic field is selectively applied thereto. In the absence of an applied field, the nematic liquid crystal molecules within each capsule tend to align with the three-dimensional boundary walls of the encapsulating material that bound the capsule, so that the overall In this case, the liquid crystal molecules do not have a uniform alignment direction as a whole.

Under such conditions, the liquid crystal molecules are insensitive to the polarization of the light incident on the device and the device is therefore substantially opaque.

When a field of appropriate strength is applied to the device, this tendency of the liquid crystal molecules to align at the boundary walls of the capsule disappears. and, under the influence of the applied field, become reoriented to a general thousand-line configuration. Under this condition, light can pass through the element.

Also, in U.S. Pat. No. 4,411,495, a liquid crystal material is dispersed in a layer of porous filter material made of cellulose ester, and the refractive index of the liquid crystal material is controlled by the application of an electric field to form a filter material. It is known to influence the selective transmission of light past a liquid crystal element by creating conditions that match or mismatch the refractive index of the liquid crystal element. If their refractive indices are matched, the device will be transparent, and under mismatched conditions it will be opaque to incident light. It will be noted that the change in refractive index is fundamental to the operability of the device constructed according to US Pat. No. 4,411,495.

[Prior art]

In order to evaluate the electro-optical characteristics of liquid crystal elements, there are various light scattering evaluation devices. For example, a light scattering measuring device using a laser as shown in FIG. 1 is commercially available. , ■Optech GP-5, CP-7
is one example.

In this device, laser light from a laser 1 is incident on a sample 3 via a mirror 2, the angular distribution of the intensity of the scattered light is detected by a photodiode 4, the output is passed through a DC amplifier 5, and then an XY recorder is used. 6. As a use, l. Measuring the radius of inertia of the scatterer, 2.
Measuring the shape of the scatterer (correlation distance); 3. Measurement of correlation distance of phase solutions; 4. This is a measurement of particle size distribution.

In addition, there are many scattering measurement devices on the market that are designed to be applied to basic research and applied research dealing with the surface science of fine particles in the fields of surface chemistry, polymers, biology, pharmacy, medicine, etc. One example is Otsuka Electronics' ELS-8φφ, which has zeta potential, electrical mobility distribution, particle size by mobility, particle size,
Particle size distribution can be measured. The device is similar in general to the GP-5 and CP-7, but the angular distribution is
The above-mentioned evaluation is made possible by measuring angles of 22° to 22°, using a photomultiplier tube as a detector, and performing advanced data processing such as fast Fourier transform.

What are the commercially available light scattering measurement devices mentioned above? It is used to analyze particle polymers, and a laser (although sometimes no laser is used) is incident on the sample to generate scattering, which is then evaluated.

[Problems to be solved by the present invention] Liquid crystal elements can perform transmissive display and are also used for display boards, windows, doors, and walls that utilize the shutter effect. The light incident on the device has a continuous distribution, such as sunlight or indoor lighting, and is not monochromatic. Therefore, when evaluating the device, correct evaluation cannot be performed unless white light having a distribution close to that of sunlight or indoor lighting is used. Furthermore, when a monochromatic light is incident on the device, interference occurs in the scattered light, and the angular distribution becomes quite different from that of a white light source.

[Means for solving problems]

The present invention creates parallel light with a narrow beam diameter using an optical system using a white light source with a continuous distribution in the visible light region and a lens, and the parallel light is incident on a light scattering material and scattered, thereby producing scattered light and transmitted light. This is a light scattering measurement device characterized by measuring the angular distribution of light intensity.

The present invention will be explained below with reference to FIGS. 2, 3, and 4. Figure 2 is an overall block diagram of the measuring device including the optical system and electrical system. , and a detector consisting of a photodiode, etc. A controller 8 connected to the main body 7 receives an output signal from a detector 10 (Fig. 3) in the zero body 7, passes this signal through a preamplifier, and then inputs it into a log amplifier to obtain a logarithmic output. , and sends this to the X2Y recorder 9. Note that the controller 8 can send the logarithmic output to the computer or, if necessary, send not only the logarithmic output but also the original linear output to a computer recorder. Furthermore, the controller 8 is adapted to send a signal for rotating the detector.

FIG. 3 shows the area around the detector part, which is a part of the optical system included in the main body 7. The detector 10 is slidably supported on a support base 11, and the support base 11 has an axis. It is pivotally connected to the base 14 so as to be rotatable about the base 12 by a motor l3 or the like. The sample stage 15 is supported by a support pedestal 16, and a lens system 17 and a white light source 18 are connected behind the sample stage 15, so that a thousand beams of light are incident on the sample S (FIG. 4) on the sample stage. ing. The detector 10 can be rotated by +90° to -90° by rotating the support base 11, but it can be rotated over a wider range if the space is made a little larger.

Furthermore, by sliding the detector 10 on the support base 11, the distance between the detector and the sample S (Fig. 4) can be changed, and the detection angle, which is one of the important factors of scattering distribution, can be changed. It becomes possible to change the

FIG. 4 is a diagram showing a light source 18 and a lens system 17. The white light source 18 is a light source of a lamp such as xenon or halogen, and in order to utilize it efficiently, a mirror is installed on the opposite side of the lens system 16. This is desirable. Furthermore, since halogen and xenon contain a considerable amount of ultraviolet light, a filter may be inserted in the optical path.

A lens system for obtaining parallel light is, for example, a white light source 1
8, there is a 50φ biconvex lens 19 in [50]
A 30φ biconvex lens 20, a 100x objective lens 21, a 2.5x projection lens 22, and a 20φ single convex lens 23 are installed in this order. A collimator 24 is placed next to the lens system, and by changing the diameter of the collimator, parallel light of 5φ to 1φ can be obtained. The spot size of the parallel light is at least 40c from the collimator 24.
There is no change at a distance of m.

As the detector 10, a photomultiplier tube can also be used in addition to a photodiode.

Furthermore, when a liquid crystal element is used as the sample S, it is necessary to apply a voltage, so a power cable for this purpose can be introduced. Furthermore, the sample stage and detector are sealed and shielded from external light. An A/D converter may be used to input the output signal to the computer, and at this time, the data of the angular distribution is saved on a floppy disk or the like.

As described above, a thousand lines of light with a narrow beam diameter are created by an optical system using a white light source with a continuous distribution in the visible light region and a lens, and the parallel light is incident on a light scattering substance and scattered. ,
A light scattering measuring device is achieved which is characterized by measuring the angular distribution of the intensity of scattered light and transmitted light.

[Evaluation Example 1] U.S. Patent No. 4,435,047, U.S. Patent No. 4,671.6
When the above-mentioned light scattering type liquid crystal element was manufactured based on No. 18 and evaluated using the apparatus of the present invention, an angular distribution as shown in FIG. 5 was obtained. The vertical axis represents the LOG scale of the optical output, and the horizontal axis represents the angle. Here, the liquid crystal elements are OV, IOV,
It was driven by a 30V 500Hz sine wave, and there is a fairly large difference in the output at 0° between 30V and O■. By applying a voltage, the transparency is improved and the output at 0°, that is, the transmitted light is increased in most cases.

In FIG. 5, no vibration due to interference is seen, making it easy to compare with other similarly made samples.

In the example of FIG. 5, it is easy to understand that the scattered light within 10' increases by applying a voltage, but if there is vibration in this, it is difficult to judge easily. Furthermore, these liquid crystal elements have a problem with scattering of white light, and are not perfect with monochromatic light.

From the above, it can be seen that the measuring device according to the present invention is effective for evaluating the liquid crystal element, but it can also be used for evaluating not only liquid crystal elements but also other samples in which scattering by white light is a problem.

C evaluation example 2] Using the apparatus shown in Figures 2 to 4, the light source was halogen 12V, 1O.
The beam diameter was 4φ using OW, and S1226 manufactured by Hamamatsu Photonics was used as the sensor. Further, as a filter, 03FCG 165 manufactured by Meliogres was installed in the optical path before the sample was incident, and only visible light was allowed to enter. The driving conditions for evaluating the two types of samples based on U.S. Pat.
In wave was used. Let the respective samples be A and B.

The sample in Figure 5 has a smaller average particle diameter than B in Figure 6, and the contrast at 0° (30V output/OV output) is almost the same as that of A and B. High visibility and low penetration.

Further, in sample B, unlike sample A, no large change in scattered light at 20 degrees or less is observed. The above measurement results are effective for analysis of the liquid crystal device.

〔effect〕

According to the present invention, parallel light with a narrow beam diameter is created using an optical system using a white light source with a continuous distribution in the visible light region and a lens, and the parallel light is incident on a light scattering material and scattered, thereby producing scattered light and transmitted light. A light scattering measuring device that is characterized by determining the angular distribution of intensity is effective for evaluating liquid crystal devices.In particular, since the light is not monochromatic, no interference occurs and accurate evaluation can be performed. In addition to liquid crystal devices, this method is also effective for other samples where scattering of white light is a problem.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional light scattering measuring device, FIG. 2 is a block diagram showing an outline of the device according to the present invention including an optical system and an electrical system, and FIGS. 3 (A) and (B) are optical This is a diagram showing the surroundings of the detector part, which is a part of the system, (A) is a plan view;
(B) is a side view, FIG. 4 is a layout diagram of a light source and a lens system, and FIGS. 5 and 6 are diagrams showing measurement results. 1...Laser, 4...Photodiode, 6...
X-Y recorder, 7...Main body, 8...Controller, 9...X-Y recorder, 10...Detector, l
1... Support stand, 15... Sample stand, 18... Light source,
19-23...Lens, S...Sample Fig. 3 13 1Z) 4 Fig. 4 Start Fig. 5 - 30'-20'-IQ" O0 IO@ 20m 30' One angle one Fig. 6 One angle procedure Revised scrip) February 20, 1991

Claims (1)

[Claims] 1) Means for creating parallel light with a narrow beam diameter using an optical system using a white light source with a continuous distribution in the visible light region and a lens, making the parallel light incident on a light scattering substance and scattering it to produce scattered light and transmitted light. 1. A light scattering measuring device comprising means for measuring the angular distribution of intensity of the light.