JPH0694515A - Light divergence characteristic measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain a light divergence characteristic measuring apparatus with which highly reproducible measurement data can be obtained in a short time and light intensity distribution while transitionally varying can also be measured. CONSTITUTION:A measuring apparatus has an objective lens 12 and a line sensor 14. The objective lens 12 is placed so that its optical axis is perpendicular to the surface of an object S to be measured. The objective lens 12 is preferably placed so that its focus coincides with a measuring point. The line sensor 14 is placed behind this objective lens 12. The line sensor 14 has a plurality of light receiving elements arranged in an array with constant pitches, and, the light receiving element outputs an electric signal corresponding to received light intensity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to lamps, LEDs and LDs.
The present invention relates to a device for measuring the angle dependence of the intensity of light emitted from a self-luminous object such as a plasma light emitter or an LCD panel that displays an image by selectively transmitting illumination light emitted from the back surface.

[0002]

2. Description of the Related Art FIG. 7 shows an example of an apparatus for measuring the angular distribution of divergent light intensity. This measuring device has a rotatable turntable 106, on which an object to be measured (for example, an LCD panel) S is arranged so as to be rotatable around a measurement point. Further, the apparatus includes a condensing optical system 104 having a condensing function at a narrow angle with respect to a measurement point, and the optical system 104
A photodetector 102 for detecting the light condensed by is provided.

To measure the angle dependence of the divergent light, the turntable 106 is turned to sequentially change the angle formed by the normal line to the object S to be measured and the optical axis of the condensing optical system 104. The light intensity is measured using the photo detector 102 together with the angle. As a result, for example, the angle-strength characteristic curve shown in FIG. 8 is obtained.

When the object to be measured is an LCD panel in particular, it is necessary to measure the contrast of an image which differs depending on the viewing angle (measuring the viewing angle) in order to examine its visibility. The contrast is measured by turning on and off the LCD panel at each angle and calculating the contrast at each time. As a result, an angle-contrast curve showing the angle dependence of the contrast as shown in FIG. 9 is obtained.

The object to be measured is a lamp, LED or LD.
In the case of a point light source such as, the condensing optical system 104 may be replaced with a slit or a pinhole. As one example,
Similar to FIG. 10, if the other party is a point light source, the angle that the slit looks at becomes the incident angle.

FIG. 10 shows a far field pattern measuring system of a semiconductor laser (LD). As shown in the figure, the semiconductor laser is fixed at the center of the turntable and is driven at a constant output by an APC circuit. The turntable is provided with a rotation variable resistor, and the angle at that time is obtained from the output X thereof. The light from the semiconductor laser enters the photodiode through the slit and its output Y
From this, the intensity of light incident on the photodiode can be obtained. Then, the far field pattern of the semiconductor laser is measured by measuring the angle (output X) and the light intensity (output Y) while rotating the turntable.

FIG. 11 shows a light scattering characteristic measuring device. This measuring device has a light source 108 for irradiating the measuring point of the measuring object S with light, and a light intensity measuring section 110 for receiving the light from the measuring point and measuring the intensity thereof. This light intensity measurement unit 1
The reference numeral 10 is provided so as to move on the circumference around the measurement point of the measuring object S. The light scattering characteristic is obtained by measuring the angle of the light intensity measuring unit 110 and the received light intensity at that time.

[0008]

These measuring devices are
It takes a lot of time and labor to perform the measurement while sequentially changing the relative angle between the measurement object and the light receiving unit. Further, since the angle is changed by a mechanical means, it is insufficient in terms of durability and reproducibility. Furthermore, when measuring not only the angle dependence of one direction but also the angle dependence of the direction orthogonal to it and the angle dependence of any other direction, remove the fixed measurement object once. Since the measurement is performed after rotating it by a predetermined angle and fixing it again,
More time and effort is required.

Further, in an element whose scattering characteristics can be controlled by an externally applied voltage, for example, a polymer dispersion type LCD panel, when the scattering degree changes from a low state to a high state, the angular intensity distribution of scattered light is accordingly I1 in FIG. Transiently changes from I3 to I3. On the contrary, when the state of high scattering degree changes to the state of low scattering degree, the angular intensity distribution of scattered light changes excessively from I3 to I1 in FIG. When the scattering degree changes, the intensity distribution indicated by I2 in FIG. 12 exists for the intermediate scattering state. However, such an intensity distribution that is in the midst of changing excessively cannot be measured by the above-described measuring device.

It is an object of the present invention to provide a light divergence characteristic measuring device capable of obtaining measurement data with good reproducibility in a short time.

A further object of the present invention is to provide a light divergence characteristic measuring device capable of measuring the light divergence characteristic in the course of excessive change.

[0012]

A light divergence characteristic measuring apparatus of the present invention has a plurality of light receiving elements arranged in at least one direction for converting received light into an electric signal corresponding to its intensity. It is provided with a measuring unit and a lens system that collects light diverging from the measurement point and guides the light emitted at a predetermined angle to a light receiving element at a predetermined position.

[0013]

The light diverging from the measuring point of the object to be measured is incident on the lens system and applied to the intensity distribution measuring means. This divergent light includes light emitted at various angles, and light emitted at a specific angle is incident on the light receiving element located at a position corresponding to that angle, and each light receiving element responds to the intensity of the incident light. Output an electric signal. As a result, the intensity distribution measuring means outputs the intensity distribution of the incident light with the resolution of the arrangement pitch of the light receiving elements.

[0014]

Embodiments of the present invention will now be described with reference to the drawings. Before describing the embodiments, the principle of the present invention will be described with reference to FIGS. 1 and 2.

As shown in FIG. 1, the objective lens 12 is arranged so that its optical axis is substantially orthogonal to the surface of the measuring object S. Behind the objective lens 12, a line sensor 14 having a plurality of light receiving elements arranged in a line at a constant pitch is arranged.

The light diverging from the measuring point O of the object S to be measured is collected by the objective lens 12 and applied to the line sensor 14. This divergent light includes light rays emitted at various angles with respect to the optical axis of the objective lens 12, and each light ray is located on the line sensor 14 at a position separated from the optical axis by a distance corresponding to the angle. Incident on. The line sensor 14 outputs the intensity distribution with the pitch resolution of the light receiving elements, and the intensity distribution with respect to the distance from the optical axis is obtained in the direction in which the light receiving elements are arranged. By performing a process of converting the distance from the optical axis into an angle with respect to the optical axis with respect to this intensity distribution, an angular distribution of divergent light can be obtained.

In the configuration of FIG. 1, when the focus of the objective lens 12 is arranged so as to coincide with the measurement point O of the measuring object S, the light traveling from the objective lens 12 to the line sensor 14 becomes a parallel light beam, so that the objective lens The distance between the line sensor 12 and the line sensor 14 is arbitrary.

However, for another reason, the line sensor 14
Is preferably arranged at the position of the exit pupil of the objective lens 12 (the rear focal plane of the objective lens 12). Next, this will be described with reference to FIG. In the description so far, the divergent light has been described as being emitted from one point of the measurement object, but in many cases, the light emitting portion actually has a two-dimensional spread. For this reason, the light emitted to the line sensor 14 has a characteristic in which the divergence characteristics from each point are shifted and overlapped. However, as shown in FIG.
When the line sensor 14 is arranged at the position of the exit pupil, the lights emitted from different points on the measuring object S are gathered at only one point on the surface of the line sensor 14. As can be seen from the above description, it is desirable that the line sensor 14 be arranged at the position of the exit pupil of the objective lens 12.

In this structure, when a normal lens having a focal length f is used as the objective lens 12, the distance h from the optical axis at the position where the light beam emitted at the angle θ with respect to the optical axis enters the line sensor 14 is as follows. Given by the formula.

H = f · sin θ When the normal lens is used as described above, the distance h is not proportional to the angle θ, and therefore the scales when the distance h is converted to the angle θ are not equal intervals. Therefore, conversion (correction) is required to obtain the angle characteristic.

On the other hand, there is a special lens having the following relationship between the distance h and the angle θ, and this lens is called an fθ lens.

H = f · θ When this fθ lens is used as an objective lens, since the distance h and the angle θ are in a proportional relationship, the intensity distribution obtained on the line sensor 14 is the intensity distribution with respect to the emission angle as it is.

Next, a first embodiment of the present invention will be described with reference to FIGS.

The light emitted from the object S to be measured becomes a parallel light flux when passing through the objective lens 12, and the half mirror 1
It is incident on 6. The half mirror 16 splits the incident light flux into two. The parallel light flux reflected by the half mirror 16 enters the imaging lens 18 to become a converging light flux, which is reflected by the prism 20 and deflected upward. This light flux is an eyepiece index 22 arranged on the focal plane of the imaging lens 18.
Image on. This image is viewed by the observer's eyes 26 using the eyepiece lens 24. On the other hand, half mirror 16
The parallel light flux transmitted through is focused by the imaging lens 28. A field stop 30 is arranged on the focal plane of the imaging lens 28, and a shutter 32 is provided slightly above it.
The light flux that has passed through the field stop 30 enters the lens 34, becomes a parallel light flux again, and enters the line sensor 14. The field stop 30 and the eyepiece index 24 have a conjugate positional relationship, a mark corresponding to the diaphragm diameter of the field stop 30 is provided on the eyepiece index 24, and the measurement range can be accurately confirmed by looking through the eyepiece lens 24.

Next, the signal processing system of this embodiment will be described with reference to FIG. The line sensor 14 has a large number of light receiving elements arranged in a line at a predetermined pitch for outputting an electric signal corresponding to the intensity of received light. The output of each light receiving element is sequentially taken out by the scanning circuit 42 and input to the amplifier 36. The output signal of the amplifier 36 is converted into a digital signal by the A / D converter 38 and input to the CPU 40. CPU
The reference numeral 40 sets the scanning speed, the timing of the trigger, etc., outputs the conditions to the scanning circuit 42 for control, and at the same time, performs calculation and correction for converting the position of the light receiving element into the emission angle with respect to the input data. Is processed. The light intensity distribution with respect to the emission angle obtained as a result of such calculation and correction processing is transferred to the output device 44 and output.

Next, the measurement procedure will be described. First,
A position to be measured is set by looking into the eyepiece lens 24. Next, temporary measurement is performed, and the result is judged by the CPU 40,
Sensitivity settings such as the storage time of the line sensor 14 are set.
Then, the main measurement is performed to measure data Ib (n) [n:
Light receiving element number] is obtained. Then, measurement is performed with the shutter 32 closed to obtain dark current data Id (n). These data Ib (n) and Id (n) are stored in the CPU 4
0 is processed.

The CPU 40 follows Ib according to the following procedure.
Process (n) and Id (n). First, the following formula is calculated to obtain the light intensity I (n) for the light receiving element number n (that is, position).

I (n) = Ib (n) -Id (n) Next, the light intensity I (n) is converted into a function of θ based on the relationship between the light receiving element number n and the emission angle θ, Injection angle θ
The light intensity I (θ) for Furthermore, this light intensity I
With respect to (θ), correction for variations in sensitivity of the optical system and the light receiving element is performed. For example, the same measurement is performed in advance on the perfect scattering plate, and the measurement value is corrected based on the measurement result.

The contrast of the LCD panel or the like is measured by the following procedure. First, when the LCD panel is on and when
The above measurement is performed for each of FF and ION
Obtain (θ) and IOFF (θ). This ION (θ) and IOFF
The contrast C (θ) with respect to the angle is obtained by performing the calculation of the following equation for (θ).

C (θ) = ION (θ) / IOFF (θ) The above-mentioned calculation and correction processing is instantaneously performed by the CPU 40, and it takes 1-2 seconds from the start of measurement to the output of results.

Next, the structure of the lens support member for simplifying the measurement in this embodiment will be described. As shown in FIG. 5, a lens support member 4 that supports the objective lens 12.
Reference numeral 5 denotes a contact portion 4 that is pressed against the measurement target portion S during measurement.
Have six. The contact portion 46 is formed in such a length that the focal point of the objective lens 12 is exactly at the measurement point inside the measurement object S when the tip thereof is brought into contact with the measurement object S. The line sensor 14 is provided on a substrate 48 fixed inside a housing 47 that holds the lens support member 45 so as to face the measurement target S via the objective lens 12. The output signal of the line sensor 14 is input to and processed by the data processing device 50 including the amplifier 36, the A / D converter 38, the CPU 40, the scanning circuit 42, and the output device 44 described above.

By using such a lens support member 45, the measurement can be performed by merely pressing the tip of the contact portion 46 against the measurement object S without adjusting the position in the optical axis direction. Therefore, the measurement can be performed in a short time.

In this embodiment, the objective lens 12 has fθ
A lens may be used, or the line sensor 14 may be arranged at the exit pupil position of the objective lens 12 (or its projected image position).

According to this embodiment, the light intensity distribution with respect to the emission angle is measured based on the light incident on the line sensor, so that the measurement can be performed in a very short time. Furthermore, if the amount of light is sufficient, the time to take in the light that becomes data is very short, so it is possible to measure the light intensity distribution during the transient change.

Next, a second embodiment of the present invention will be described with reference to FIG.

The measuring object S is fixed to the installation table 54.
The installation table 54 has an opening, and the measurement point of the measuring object S is illuminated by the light source 52 through this opening. The light source 52 is provided so that the distance to the measurement target and the incident angle of light to the measurement target can be adjusted. An objective lens 56 is provided on the opposite side of the light source 52 with respect to the measuring object S. The objective lens 56 is provided so that the distance to the measurement target and the angle of its optical axis with respect to the measurement target can be adjusted. A two-dimensional CCD array 58 is provided on the exit side of the objective lens 56. The CCD array 58 is provided so that the distance to the measurement object, the angle of the light source with respect to the emission optical axis, and the position in a plane parallel to the measurement object can be adjusted.

In the following, a He-Ne laser is used as the light source 52, and the light source 52 is arranged so that its emitted light is vertically incident on the object to be measured, and the objective lens 56 has its optical axis as the emitted light of the light source. The measurement performed in the setting in which the CCD array 58 is arranged so that its axis coincides with the focal point of the object to be measured and the light receiving surface of the CCD array 58 is orthogonal to the emission optical axis of the light source will be described.

The light L0 emitted from the light source 52 is incident on the measuring point of the measuring object S. The light L1 scattered from the measuring point of the measuring object S is incident on the objective lens 56 and collimated light beam L2.
And enters the CCD array 58. CCD array 5
8 has a large number of CCD elements arranged two-dimensionally, and each CC
The D element outputs an electric signal according to the intensity of received light. Each CC
While processing the output signal of the D element and the position in correspondence with each other,
By converting the CCD position into the emission angle, the intensity distribution of scattered light with respect to the emission angle can be obtained.

According to this embodiment, in addition to the effect obtained in the first embodiment, since the CCD array which is a two-dimensional sensor is used, the scattered light intensity with respect to the angle in each direction can be measured at one time. it can.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the invention. For example, in the first embodiment, by providing a means for rotating the line sensor about the optical axis, it is possible to obtain the light intensity distribution with respect to the emission angle in an arbitrary direction. Further, in the second embodiment, the He-Ne laser is used as the light source 52, but another laser may be used.
Further, an optical system in which a lens and a diaphragm are combined with a tungsten lamp, a halogen lamp, a metal halide lamp, or the like to increase the parallelism of emitted light may be used as a light source.

[0041]

According to the present invention, since there is no mechanically moving member, it is possible to obtain reproducible measurement data in a short time. Furthermore, since the time for taking in the light as the measurement data is very short, it is possible to measure the light intensity distribution during the transient change.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the principle of the present invention.

FIG. 2 shows an optical path of light when a line sensor is arranged at an exit pupil position of an objective lens.

FIG. 3 shows a configuration of a measuring apparatus that is a first embodiment of the present invention.

FIG. 4 shows a configuration of a signal processing system connected to the line sensor of FIG.

FIG. 5 shows a structure of a lens support member that makes measurement easier in the apparatus of FIG.

FIG. 6 shows a configuration of a measuring apparatus according to a second embodiment of the present invention.

FIG. 7 shows a configuration of a conventional measuring device.

FIG. 8 is a graph showing a light intensity distribution with respect to an angle.

FIG. 9 is a graph showing the angle dependence of the contrast of the LCD panel.

FIG. 10 shows a far-field pattern measuring system of a semiconductor laser.

FIG. 11 shows the configuration of another conventional measuring apparatus.

FIG. 12 is a graph showing how the light intensity distribution changes excessively.

[Explanation of symbols]

 12 ... Objective lens, 14 ... Line sensor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Adachi 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (1)

[Claims] 1. A device for measuring an intensity distribution with respect to an angle of light diverging from a measurement point of an object to be measured, comprising a plurality of light receiving elements for converting received light into an electric signal according to the intensity, The plurality of light receiving elements are arranged in at least one direction, the intensity distribution measuring means for measuring the intensity distribution along the direction, and the light diverging from the measurement point is condensed and the light emitted at a predetermined angle is emitted at a predetermined angle. A device for measuring light divergence characteristics, which comprises a lens system for guiding a light receiving element at a position.