JPS61213638A - Measuring instrument for visual sensitivity - Google Patents

Abstract

PURPOSE:To obtain a measuring instrument which facilitates corrections of angular characteristics of equivalent light curtain brightness by providing a photodetection window which has diffuse transmission characteristics, a light shielding plate, a condenser lens, a mask for parallel light, a photodetector, etc. CONSTITUTION:Equivalent light curtain brightness (Lev) information from a measure ment visual field of max. 180 deg. is incident on the photodetection window 37. In considera tion of characteristics of Lev, the information is passed through aperture parts of light shield plates 38 and 39, converged by the condenser lens 40, and then made entered into the photodetector 43 for Lev through the mask 41 for parallel light and a diffusing plate 42 so as to extract only a parallel light component from the incident light. Further, the photodetection window 37 has diffuse transmission characteristics and is increased in diffuse transmissivity at a part (a) of the optical axis center part of the window 37 and made lower in diffuse transmissivity at a part (b) of the periph eral part than at the optical axis center part to equalize angular characteristics of Lev to a logical value. Then, an Lev measurement system is not an image formation system, so the influence of variances in cosine biquadratic rule characteristics and aperture efficiency characteristics is hard to exert.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a measuring device for determining the brightness of a visual object.

Conventional technology The "brightness" of a visual object (hereinafter referred to as congratulatory brightness B) existing in a visual environment with a complex brightness distribution in general is expressed as the brightness of the visual object Lo (hereinafter referred to as Lo). Luminance discrimination ΔL corresponding to the adapted luminance of the eye of the observer who sees it
It is quantitatively determined as a function of min (hereinafter referred to as ΔL min). For example, congratulatory brightness B is.

"="gl"" (l Lmin)"'"'"
'(1).

Here, as shown in Japanese Unexamined Patent Publication No. 65-46185, ΔL win is the foveal adaptation luminance Lf' (hereinafter referred to as Lf) of the observer and the equivalent light curtain luminance Lema (hereinafter referred to as Lf).

(called Loma).

Therefore, the congratulatory brightness B can be determined from the three types of brightness measurement values Lf, Loma, and Lo using the procedure shown in FIG. 4.

In FIG. 4, the foveal adaptation brightness Lf is measured at &. In b, the equivalent light curtain luminance Lev is measured.

At C, the visual object brightness LO is measured. In d, the luminance difference discrimination ΔLf related to the foveal adaptation luminance is determined. In e, a luminance difference discrimination ΔLe matrix related to the equivalent light screen luminance is determined. At f, ΔL is determined by brightness difference discrimination. At C, congratulatory brightness B is determined.

Based on such measurement principles, specific measurement devices include Lf' measurement system, Lav measurement system, as shown in Fig. 6.
A congratulatory luminance measurement device is being considered in which the Lo measurement system and the finder system are configured with the same optical system.

The conventional congratulatory luminance measuring device described above will be explained below.

FIG. 5 shows the configuration of the optical system of the congratulatory luminance measuring device, and 1 is a visual object within the field of view. 2 is an objective lens for guiding an image containing luminance information of the viewing object 1 to a light receiver or finder, which will be described later; 3.4 and 6.6 are for guiding an image from the objective lens 2 to a light receiver or finder. A half prism to be separated, 7 is a mask that limits the LO measurement viewing angle, 8
1 is a diffuser plate that diffuses the light flux (brightness) that has passed through the mask 7; 9 is a light receiver that receives Lo; 10 is a mask that limits the Lf measurement viewing angle; 11 is a light flux (brightness) that has passed through the mask 10 12 is a light receiver for receiving Lf; 13 is a correction filter that corrects the angular characteristic (1/θ2 characteristic) of Lev; 14 is a correction filter 13
A diffuser plate that diffuses the luminous flux (luminance) that has passed through the
16 is a reticle displaying the measurement range of LO and Lf; 17 is a finder for confirming the measurement range of Lo and Lf; 18, 19, 20, 21
．． 22, the image from the objective lens 2 is transmitted to the light receiver 9 and the light receiver 1.
These are relay lenses that each lead to the 5° finder 1T.

To explain the operation of the conventional congratulatory luminance measuring device configured as described above, first, the visual object 1 in the field of view is detected by the objective lens 2.
As a result, an image is formed at the X position as an aerial image. In this case, the viewing angle (angle of view) of the objective lens 2 is required to be 1112LX, 180' due to the characteristics of Lev, so an ultra-wide-angle lens is used.

After the image formed on X passes through the relay lens 18,
Half prism 4 → Half prism 3 → Relay lens 1
9 → mask 7 → diffuser plate 8 → guided to light receiver 9 (Lo
(Measurement of Lf), along with No. 4 -> relay lens 20 -> mask 1o -> diffuser plate 11 -> light receiver 12 (measurement of Lf), and then half prism 4 -> half prism 6 ->
Relay lens 21 → reticle 16 → guide to finder 17 (confirmation of measurement range with finder), and finally.

Half prism 4 → Half prism 5 → Half prism 6 → Relay lens 22 → Correction filter 13 → Diffusion plate 14
→It goes to the light receiver 15 (Lev measurement).

Each will be guided.

In this way, three types of brightness measurements are performed, and the congratulatory brightness B is measured by performing arithmetic processing on these measured values.

As described above, in the operation of the conventional congratulatory luminance measurement device, L
Since the O measurement system, Lf measurement system, Lev measurement system, and finder system have the same optical axis and can perform simultaneous measurements, we attempted to measure the congratulatory luminance at the same location using one measurement device. be.

In such a configuration, the correction filter 13 has a characteristic that the transmittance Lf' of light incident at an angle θ with respect to the center of the optical axis is attenuated by K cos θ/θ2 (K is a constant) as shown in FIG. It was made so that it would become so.

Since this characteristic varies in the cosine-fourth power side characteristic and the aperture efficiency characteristic of the objective lens 2, it is necessary to also correct these characteristics, and accuracy of the angular characteristic (transmittance characteristic) is required.

Typically, such properties are obtained by depositing a thin film layer with a concentration gradient on a glass or quartz substrate. So-called neutral density filters are known. However, when manufacturing these filters, when the transmittance reaches about 10-4% as mentioned above, it becomes difficult to control the transmittance during manufacturing, and the actual situation is that desired characteristics cannot be obtained.

Problems to be Solved by the Invention In such a conventional configuration, the cosine fourth power side characteristics and the aperture efficiency characteristics of the objective lens 2 are determined in advance, and a correction filter that matches the characteristics of each objective lens is created. There was the problem of having to manufacture the product each time.

The present invention solves the above-mentioned conventional problems.

It is an object of the present invention to provide a congratulatory brightness measuring device that facilitates correction of the angular characteristics of the equivalent light curtain brightness Lev.

Means to solve problems The present invention relates to a measurement system for equivalent light screen luminance Le.

A light-receiving window having diffuse transmission characteristics, a light-shielding plate having an opening that takes out only the parallel light component from the light-receiving window, a condenser lens that allows the parallel light that has passed through the light-shielding plate to enter a light receiver to be described later, and a condenser lens. This is a congratulatory luminance measurement device equipped with a mask that allows parallel light components to pass through, and a light receiver that receives Lev from the parallel light mask, and the diffused transmission at the center of the optical axis of the light receiving window that has a uniform thickness. The angular characteristic of Lev can be made to match the theoretical value by increasing the transmittance and making the diffuse transmittance in the peripheral area lower than that in the center of the optical axis.

action The effect of this technical means is as follows.

That is, in the present invention, materials with known diffuse transmission characteristics can be used for the light receiving window, and desired characteristics can be easily obtained by combining them. Furthermore, since the Lev measurement system is not an imaging system like the conventional example, it is less susceptible to variations in cosine-fourth power side characteristics and aperture efficiency characteristics.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

FIG. 1 shows a configuration diagram of the optical system of the congratulatory luminance measuring device. In FIG. 1, 23 is a visual object within the visual field. Reference numeral 24 denotes an objective lens for guiding an optical image containing luminance information of the viewing object 23 to a light receiver or finder, which will be described later. Reference numeral 26 indicates an objective lens for guiding an optical image containing luminance information of the viewing object 23 to a light receiver or a finder, which will be described later. A perforated mirror for guiding the light to the finder and limiting the viewing angle (1° to 2°) for measuring the luminance LO of the visible object; 26 is a diffuser for diffusing the luminous flux (brightness) that has passed through the hole of the perforated mirror 25; 28 is a half prism that separates the foveal adaptation brightness measurement system from the finder system; 29 is a measurement viewing angle (1
00 to 20'), 30 is a diffusion plate that diffuses the luminous flux (luminance) that has passed through the mask 29, and 31 is Lf.
A light receiver (with visibility correction) 32 is for re-imaging the optical image of the visual object 23 formed at the position of the perforated mirror 25 at the position of the Lf mask 29 and the reticle, which will be described later. 33 and 34 are relay lenses for guiding the optical image partially reflected by the half prism 28 to the finder system, and 36 is a reticle displaying the LO and Lf measurement ranges.

36 beams, and a finder (viewing angle 30') for checking the measurement range of I and f; 37 a light receiving window (with diffuse transmission characteristics) for measuring the equivalent light screen brightness Lav at a viewing angle of 16oO to 18o0; ), 38 and 39 are light receiving windows 37
A light shielding plate 40 has an aperture (circular) for extracting only the parallel light component out of the L6 luminance information incident on the light shielding plate 38, 39. The light shielding plate 40 collects the parallel light that has passed through the light shielding plate 38 and 39, and sends it to the light receiver described later. 41 is a mask that allows the parallel light component from the condenser lens 4o to pass through; 42 is a diffuser plate that diffuses the luminous flux (luminance) from the parallel light mask 41; 43 is a light receiver (for receiving Lev); (visual sensitivity corrected).

The operation of the congratulatory luminance measuring device according to the embodiment of the present invention configured as described above will be described below.

In FIG. 1, an optical image of a visual object 23 is formed by an objective lens 2
4, passes through a hole in a partially perforated mirror 25, passes through a diffuser plate 26, and reaches an LO light receiver 27. Glue to the perforated mirror 26.

An opening (circular hole) is provided with a size that limits the measurement viewing angle (10 to 2 degrees). The above is the LO measurement operation.

On the other hand, the optical image reflected by a portion of the perforated mirror 25 passes through the intermediate lens 32 and is separated into the Lf measurement system and the finder system by the half prism 28, and then the transmitted light (optical image) is An image is formed at the position of the mask 29. The mask 29 has a measurement viewing angle of Lf (10° to 2o0
), and after passing through the mask 29, the Lf luminance information reaches the Lf light receiver 31 via the diffuser plate 3o. The above is the Lf measurement operation.

Further, the reflected light (optical image) from the half prism 28 passes through relay lenses 33 and 34, and then passes through the reticle 35.
The image is formed at the position of The reticle 35 displays circles of 1° to 2° and 100 to 2o0 so that the measurement ranges of LO and Lf can be seen. The finder 36 allows the measurer to check the measurement ranges of Lo and Lf.

The operations of the LO measurement system, Lf measurement system, and finder system have been explained above, and next, the operation of the L6 measurement system will be explained.

In FIG. 1, the light receiving window 37 is m&X. Lat luminance information from within the measurement field of view of 18o0 is incident. Due to the characteristics of the LO beam, in order to extract only the parallel light component of these incident lights, the light is passed through the openings of the light shielding plates 38 and 39, condensed by the condenser lens 40, and then passed through the parallel light mask 41. The light passes through the diffuser plate 42 and reaches the La light receiver 43.

The light-receiving window 3γ has a diffuse transmission characteristic, and in the present invention, the diffuse transmittance of the optical axis center portion of the light-receiving window 37 (around the objective lens 24, the part a in the figure) is made high.

The diffused transmittance of the peripheral portion (portion b in the figure) is lower than that of the central portion of the optical axis. Here, the light-receiving window 37 is made of optical glass having a uniform thickness, and the diffuse transmission characteristics of a and b mentioned above are as shown in FIG.

In the case of optical glass, methods for achieving the diffuse transmission characteristics of the light receiving window 37 include methods for mechanically obtaining the diffuse transmission characteristics, such as roughening the glass surface by sanding, polishing, direct pressing, etc., and chemical methods. One possible method is to obtain diffuse transmission characteristics, for example, by roughening the glass surface with hydrogen fluoride or the like.

Here, as an example, the light receiving window 37 (diameter φ703111)
is machined, that is, sanded and polished to form part a (φ2
o~φ4o1nIl) and part b (φ40~φ7oso
g) and have different diffuse transmission characteristics, and then L
When the angular characteristics of the 6-ma measurement system were determined, the results shown in Figure 3 were obtained. From the results shown in FIG. 3, it can be seen that the desired angular characteristics can be obtained by the above method.

In this embodiment, optical glass is used for the light receiving window 37, but instead of optical glass, a combination of resins with different diffuse transmission characteristics (for example, Mitsubishi Acrylite, Sumitomo Sumipex: both trade names), It goes without saying that properties similar to those of the above-mentioned optical glass can also be obtained by molding (providing a diffusing surface on one side), attaching a film or sheet having diffuse transmission properties, etc.

As described above, according to this embodiment, in the one-equivalent light curtain luminance measurement system, the light receiving window that receives the equivalent light curtain luminance information from the viewing angle of 1800 is made of two or more types of materials having diffuse transmission characteristics. By increasing the diffuse transmittance at the center of the optical axis of the light receiving window and lowering the diffuse transmittance at the periphery than at the center of the optical axis, the angular characteristics of the LO beam can be easily matched to the theoretical values. .

Effects of the Invention As is clear from the above description of the embodiments, the congratulatory luminance measuring device of the present invention has a light receiving window having a diffuse transmission characteristic and a parallel A light shielding plate having an opening that takes out only light components, a condenser lens that allows the parallel light that has passed through the light shielding plate to enter a light receiver, a parallel light mask that allows the parallel light component from the condenser lens to pass, and a parallel light mask. A light receiver is provided for receiving LO beams from By determining a combination that makes the transmittance lower than the center of the optical axis, the angular characteristics of the LO beam can be made to match the theoretical values.

Furthermore, since the Lema measurement system in this embodiment is not an imaging system like the conventional example, it has the advantage of being less susceptible to variations in the cosine fourth power side characteristics and the aperture efficiency characteristics.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an optical system in a congratulatory luminance measuring device according to an embodiment of the present invention, Fig. 2 is a diagram showing the diffuse transmission characteristics of the light receiving window in the embodiment, and Fig. 3 is an equivalent light curtain luminance in the embodiment. Figure 4 is a diagram showing the angular characteristics of the measurement system, Figure 4 is a diagram showing the principle of congratulatory luminance measurement, Figure 6 is a configuration diagram of the optical system of a conventional congratulatory luminance measurement device, and Figure 6 is the angle of equivalent light curtain luminance. It is a theoretical characteristic diagram of characteristics. 23... Visual object, 24... Objective lens, 26... Hole mirror, 26, 3o, 42
...Diffusion board. 27.31,43...Receiver, 28...
・Half prism, 29...Mask, 32...
...Intermediate lens, 33.34...Relay lens, 36...Reticle, 36...Finder, 37...Light receiving window, 38°39... ...
- Light shielding plate, 40... Condenser lens. 41...Mask for parallel light. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure *At O(de3) -qth'! -14H (%)+
擾hir=H% Figure 3 θ(ds)

Claims (1)

[Claims] Equivalent light that has a uniform thickness and is made of materials with two or more types of diffuse transmission characteristics, and has a high diffuse transmittance at the center of the optical axis and a lower diffuse transmittance at the periphery than at the center of the optical axis. a light-receiving window for curtain luminance, a light-shielding plate having an opening that takes out only the parallel light component from the light-receiving window, and a condenser lens that causes the parallel light that has passed through the light-shielding plate to enter the light receiver;
An equivalent light curtain brightness measurement system consisting of a mask that allows the parallel light component from the condenser lens to pass through, and a light receiver that receives equivalent light curtain brightness information from the parallel light mask, and a visual object that includes an imaging system. A visual luminance measurement device equipped with a luminance measurement system, a foveal adaptation luminance measurement system, and a finder system.