JPH0331802A - Phase type diffuser plate and its manufacturing method - Google Patents

Abstract

PURPOSE:To observe an excellent finder image which has neither a color irregularity nor a telephoto spot as the function of a focus plate by providing four kinds of different-height plane parts of fine patterns on a substrate, and generating four kinds of phase differences. CONSTITUTION:A 1st level is generated by the reference surface 1 of the substrate 11 and incident luminous flux is provided with a phase difference theta1 by a 1st uneven pattern 2 to generate a 2nd level. Then the incident luminous flux is provided with a phase difference theta2 by a pattern overlapping with the 1st uneven pattern 2 by a 2nd uneven pattern 3 to generate a 3rd level. Further, a 4th level for providing the incident luminous flux with a phase difference (theta1+theta2) is generated by a 3rd uneven pattern 4 in the area where the 1st uneven pattern 2 and 2nd uneven pattern 3 overlap with each other. When this plate is used as the focus plate, an excellent image is obtained by the phase differences of those four levels.

Description

[Detailed description of the invention] (Application field on R1) The present invention relates to a phase type diffuser plate and a method for manufacturing the same.

For example, the present invention relates to a phase-type diffuser plate that has predetermined diffusion characteristics and enables good observation of a finder image when used as a focus plate for forming a finder image in a photographic camera, and a method for manufacturing the same.

(Prior art) Conventionally, a plurality of fine patterns of a predetermined shape and a constant height are formed on an optically transparent substrate surface, and a phase difference is imparted to the light beam passing through the Makoto fine pattern with respect to other light beams. A so-called bi-(pi) level phase type diffuser plate which has a predetermined diffusion characteristic is proposed, for example, in Japanese Patent Laid-Open No. 55-70827.

FIG. 4 is a schematic diagram of the main parts of the pi-level phase type diffuser plate proposed in the publication. In the figure, 101 is a substrate, and a fine pattern +02 of a constant height is formed on the substrate lO1[IjE. Then, a phase difference is created between the light beam passing through the area on the surface of the substrate 101 and the light beam passing through the area B of the pattern 102, and a predetermined diffusion characteristic is obtained.

(Problem to be solved by the invention) When a light beam is incident on a phase type diffuser plate, as shown in FIG.
Next time, the 11th, 12th, etc. of a predetermined intensity centering on strong light.
The 0-phase type diffuser plate, which generates diffracted light such as , obtains desired diffusion characteristics.

In general, when the focal length of a pie-level phase type diffuser plate is long when the shooting lens is wide open, the hazy image formation position is not aligned compared to a standard lens, and the light rays become vignetted, the peripheral brightness decreases, or the so-called telephoto spot is caused by color unevenness. will occur.

Further, since the pie-level phase type diffuser plate has poor dispersion characteristics, color unevenness occurs in the blurred image when the aperture is wide open or when the aperture is small. This color unevenness depends on almost bi-level cleanliness, and it is very difficult to correct it.

Moreover, the minimum actual measurement of the intensity of the 0th order strong light is about 4 to 5%, and it is difficult to make it smaller than this, which poses the problem that, for example, it is not possible to greatly blur the finder image.

The present invention has a predetermined pattern of irregularities with different phase differences and a Wi number of concave and convex portions on the substrate surface, so that when applied to a finder system, for example, there is less white zero-order light and a symmetrical bokeh is achieved. The object of the present invention is to provide a phase-type diffuser plate which prevents the occurrence of one-color unevenness and the accompanying telephoto spot and enables observation of a good viewfinder image.

(Means for Solving the Problems) The phase-type diffuser plate base of the present invention has a first concavo-convex pattern on an optically transparent substrate surface F, using the substrate surface as a reference plane, which imparts a phase difference θ1 to an incident light beam. A second uneven pattern is provided which imparts a phase difference θ2 to the incident light beam so as to coincide with at least a part of the pattern of the first uneven pattern, and a total of four phase differences 0 and θ1 are provided to the incident light beam. ．． θ2.
(θ1+02), the incident light beam is diffracted and/or scattered to obtain desired diffusion characteristics.

Further, the phase type diffuser plate according to the present invention is characterized in that it is manufactured by the following process. That is, a first step of forming a photoreceptor on a substrate surface, exposing, developing or bleaching a predetermined pattern, and forming a first uneven pattern on the substrate surface by first etching, and then forming a photoreceptor on the substrate surface. a second step of removing the photoreceptor remaining on the substrate; and forming a photoreceptor on the surface of the substrate.

j. A third step of arranging a predetermined pattern so as to overlap at least a part of the pattern of the first concavo-convex pattern, and exposing, developing or bleaching the pattern, and an etching process different from the first etching. A fourth step of forming a second concave-convex pattern on the substrate surface by a second etching process provides four different phase differences to the incident light beam as a whole, thereby diffracting the incident light beam and/or The desired diffusion properties are obtained by scattering.

(Embodiment) FIG. 1(A) is a perspective view of the main part of the first embodiment of the present invention.
Figure (B) is a sectional view taken along line AA in Figure (A).

In the figure, reference numeral 11 denotes a substrate made of an optically transparent material.

The surface of the substrate II serves as a reference plane I and forms a first rubel.

2 is the first uneven pattern, which is the reference surface of the substrate 11 in the figure! It is made up of a concave pattern that imparts a phase difference θl to the incident light beam, and forms a second level. Reference numeral 3 denotes a second concave-convex pattern, which is composed of a pattern that overlaps at least a part of the pattern of the first concave-convex pattern 2, and in the figure, it is composed of a concave pattern that imparts a phase difference θ2 to the incident light beam; forming a level,
4 is the third uneven pattern, which is the first uneven pattern 2 and the second uneven pattern.
It consists of areas where the uneven pattern 3 overlaps with each other,
A fourth level is formed that gives a phase difference (ol+02) of <- to the incident light beam.

The first level 1 to the fourth level 4 are each made up of four different heights, as shown in FIG. 1 (13). As a result, different phase differences 0, θl, θ2, .
(θl+θ2), that is, a four-level phase difference is provided, and the incident light beam is diffracted and/or scattered, thereby forming a so-called 4-level phase type diffuser plate that has a desired diffusion characteristic of 44 degrees.

In the pie-level phase type diffuser plate, the white 0th-order light has a blue or red component remaining, and a color difference occurs between blue and red.

On the other hand, in this embodiment, the total diffused light passing through the diffuser plate is divided between the light beams passing through the reference surface l and the first uneven pattern (i=■, 2.3), and between the first uneven pattern and the first uneven pattern. (j=2.3)
The light beams that passed through the uneven pattern and the third uneven butterfly! [The light beams combine and illuminate each other to form a beam of light.

In other words, the colors of such combinations of light beams cancel each other out, making the spectral characteristics of the total diffused light flat, thereby making it possible to observe a good finder image without color unevenness.

In particular, in this embodiment, the color of white zero-order light can be made closer to white than in a pie-level phase type diffuser plate, and color unevenness is reduced.

In the 4-level phase type diffusion plate in this embodiment, the unit case f- of the pattern for aligning the items Φ is not point symmetrical (deviated by more than μm), similar to the pi-level phase type diffusion plate.
If the small patterns are arranged and the unit cell does not have a periodic structure, the graininess due to the uneven pattern will be 1-1q when observed with a finder system.

Therefore, in this embodiment, as shown in the flowchart of FIG. 3, a four-level phase magnification plate is manufactured by the following method.

First, as the first L culm, a photosensitive resin film, a silver salt film,
Then, a photoreceptor such as a high-resolution positive resist is formed,
A predetermined pattern mask is exposed, developed, or bleached by exposing, developing, or bleaching, and forming a pattern image by facing the WtL2 closely or with a small gap therebetween, or by reducing and projecting the mask through a projection system.

Second, as a culm, A is etched on the transfer substrate surface by the first etching.
A first concavo-convex pattern based on the pattern is formed to have a predetermined cleanliness so as to impart a phase difference θ1 to the passing light beam, and then the photoreceptor and other unnecessary materials remaining on the substrate F are removed.

Thirdly, as a culm, the 11th Fi! A photoconductor similar to the above is formed, and the mask pattern is pattern 8! of the first concavo-convex pattern! For example, the master and mask pattern are rotated or displaced in a predetermined manner so that at least a portion of the mask pattern shields each other, and exposed, developed, or bleached in the same manner as in step C.

As the fourth etching process, the second etching process, which is different from the first etching ring in the second step, is performed to form a 3-λ etching ring.
On the board. A second concave-convex pattern is formed to have a predetermined cleanness so as to impart a phase difference θ2 to the passing light beam,
Remove the photoreceptor and other unnecessary items on the A h surface.

At this time, in this embodiment, the phase difference θ due to the first etching is
The phase difference θ2 due to l and the second etching is θ1<θ2
When θ1/θ2<0.95, θ1/θ2>1.05.

In this embodiment, four phases 70, θl, θ2゜〈θ1+θ2〜〈θ1+θ2〜, which are totally different from each other with respect to the incident light beam, are thus obtained.
By imparting this, the incident light beam is diffracted and/or scattered to obtain desired diffusion characteristics in a circular manner.

(Without considering the physical numbers, the IiI length of the target light is λ, and the refractive index of the material for the C group is 02 as shown in Figure 1 (13). The cleanliness corresponding to the phase difference θl is (11,□+, Lrj The cleanliness corresponding to the phase difference θ is d
, 1. When the purity corresponding to I'L phase difference (θI+1)2) is defined as d snow, in this embodiment, the crystal key tree is constructed from the following F1 values.

(a flf1 example 1) θ1 = d, (n-11 = 0.45802
=d+-*(n-1)=0.5980l+02
= d t (n -1) = 1, 04 people (
Numerical example 2) 171 = d, -, (n-1) -0, 39 people 02
=dl-1(n-1)=0.53 people θ1+02
=d*(n-1)=0.92 people 2nd IN is a perspective view of a main part of a second embodiment of the present invention.

In this figure, the same elements as in FIG. 1(A) are given the same reference numerals.

In this embodiment, when forming the second uneven pattern 3, the pattern is formed so as to include all of the pattern of the first uneven pattern 2, and the third uneven pattern 4 is formed from an area where both areas overlap. There is.

Similarly to the first embodiment shown in FIG. 1(A), there are four phase differences of 0 and 01.0 with respect to the incident light beam with respect to the reference plane l.
2. <01+02) is added, that is, a four-level phase difference is imparted to obtain a four-level phase type diffuser plate having desired diffusion characteristics.

(Effects of the Invention) According to the present invention, as described in I1I, by providing on the substrate surface four types of f-plane portions having different heights, m, which are composed of a plurality of fine patterns having a predetermined shape, and having four phase differences. 1 For example, when used as a focusing plate for a photographic camera 2
A focusing plate having the following effects can be obtained.

(b) Since the coloring of the O-order light is small, even when using a standard lens with a small aperture, the entire field of view in the viewfinder will not be colored by the color of the 0-order light and will exhibit natural colors. You can obtain a viewfinder image that looks like this.

(b) Since the coloring of the 0th order light is small, it is possible to prevent the occurrence of a telephoto spot and reduce color unevenness even when the aperture is set to a small aperture in a lens system such as a telephoto lens where the eyes do not match. I can do it.

(c) Since the intensity of the white zero-order light can be weakened, it is possible to increase the blur, and it is also possible to reduce the unevenness of the light layer when the aperture is set to a small aperture in a telephoto lens.

(d) A diffuser plate having four levels of phase difference can be easily manufactured by repeating the same 5J ball-making process twice.

[Brief explanation of drawings]

1(A) and 2 are perspective views of essential parts of the first and second embodiments of the present invention, FIG. 1(B) is a sectional view taken along line AA in FIG. 1(A), and FIG. 4 is a flowchart of an embodiment of the method for manufacturing a phase type diffuser plate of the present invention, FIG. 4 is a perspective view of essential parts of a conventional phase type diffuser plate, and FIG. 5 is an explanatory diagram of diffracted light passing through the phase type diffuser plate. It is. In the figure, 11 is the substrate, l is the reference surface, 2 is the first uneven pattern,
3 is a second uneven pattern, and 4 is a third uneven pattern. Figure 1 Figure 2

Claims (2)

[Claims] (1) A first uneven pattern that imparts a phase difference θ1 to an incident light beam is provided on an optically transparent substrate surface, using the substrate surface as a reference surface, and overlaps at least a part of the pattern of the first uneven pattern. By providing a second concavo-convex pattern that imparts a phase difference θ2 to the incident light beam, and imparting a total of four phase differences 0, θ1, θ2, (θ1+θ2) to the incident light beam, the incident light beam can be diffracted or / and a phase type diffuser plate characterized in that a desired diffusion characteristic is obtained by scattering. (2) A first step of forming a photoreceptor on the substrate surface, exposing, developing or bleaching a predetermined pattern, and forming a first uneven pattern on the substrate surface by first etching, and then forming a first uneven pattern on the substrate surface. a second step of removing the photoreceptor remaining on the substrate, forming a photoreceptor on the substrate surface, arranging a predetermined pattern so as to overlap at least a part of the pattern of the first uneven pattern; and a fourth step of forming a second uneven pattern on the substrate surface by a second etching having an etching amount different from the first etching. 1. A method for manufacturing a phase type diffuser plate, characterized in that a desired diffusion characteristic is obtained by diffracting and/or scattering an incident light beam by imparting four different phase differences as a whole.