JPH02277002A - Optical component for uniforming luminous flux - Google Patents

Abstract

PURPOSE:To obtain the optical component which is reducible in size and uniforms luminous flux with high efficiency by setting specific orthogonal coordinate axes and specifying both surfaces forming each prism unit and the array directions of respective prism units. CONSTITUTION:A body formed by laminating both saw-tooth transparent bodies which have prism units formed on a couple of opposite surfaces or a transparent body in a similar shape is used; and one of the couple of surfaces is used as an incidence surface, and the other is used as a projection surface. When an X axis is set at right angles to both those surfaces and a Y axis is set in parallel to a Z axis, the ridges of both surfaces constituting the respective prism units are parallel to the Z axis, the array direction of the respective prism units coincides with the direction of a Y axis, and both surfaces constituting each prism unit are at an angle theta or -theta shown by an X group and expressions I and II. Here, delta is a smaller angle between the divergence angle of incident luminous flux and the divergence angle (+ or -delta) that a device which utilizes projection luminous flux can utilize and less than theta0 and (n) is the refractive index of the transparent body. This constitution can uniform the light intensity of even irregular luminous flux and a light source like this can easily be manufactured.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a uniform and unidirectional light flux required for the light incident portion of an optical fiber light guide, the illumination light source of a slide projector, etc. Regarding the technology to obtain.

[Prior art] Line light sources used in defect inspection equipment for sheet materials,
Optical fiber light guides are used as cold light sources in liquid crystal pack lights, etc. in LCD printers, but in order to obtain high quality illumination with no illumination salt, these light beam incident areas are equipped with a light guide to make the incident light uniform. Devices using a diffuser plate or an optical fiber and a light guide as described in Japanese Patent Application No. 63-106779 have been devised.

Additionally, an optical system using a relay condenser is generally used in the light source section of a slide projector to prevent uneven brightness throughout the projected image.

[Problems to be Solved by the Invention] The characteristics required of these light source sections or light source uniformizing means are as follows.

(1) The amount of light is uniform throughout.

(2) High efficiency.

Furthermore, considering cost and practicality, (3) Easy to design and produce.

(4) It is small and does not take up much space.

It is also important that

The method using the above-mentioned diffusion plate and the patent application No. 1067-1983
The method using optical fibers and light guides in No. 79 uses reflective curved surfaces and lenses to create a directional light beam, which is passed through a homogenizing component to remove brightness irregularities, but the former uses a diffuser. The angle at which the light rays are scattered by the plate is large;
The efficiency is extremely low because the beam properties of the light are impaired and the light that does not fit within the aperture angle of the optical fiber becomes a loss. on the other hand,
The latter has good uniformity performance and is efficient without impairing the beam properties of light, but it is difficult to miniaturize, and the random mixing method is not easy to mass-produce while maintaining quality.

Furthermore, the optical system using the relay condenser described above has good uniformity performance and is not too bad in efficiency, but it requires careful design and adjustment of the bulb 9 reflector, condenser lens, etc., and requires advanced technology. is required. Therefore, within the scope of the prior art, it is difficult to realize an optical system that simultaneously satisfies (1) to (4).

[Means for Solving the Problems] In view of the problems of the prior art described above, an object of the present invention is to provide an optical component that can be miniaturized and can uniformize the luminous flux with high efficiency.

In order to achieve the above objects, the optical component for uniformizing the light flux of the present invention has a double sawtooth shape in which a plurality of prism pieces serving as units (hereinafter referred to as prism units) are formed on a pair of opposing surfaces. A laminated transparent body or a transparent body having a shape similar to the laminated body; When the X-axis is perpendicular to , the Z-axis is perpendicular to the stacking direction of both the serrated transparent bodies, and the Y-axis is perpendicular to both the X-axis and the Z-axis, the ridge line formed by both surfaces of each prism unit is 2 axes, (b) the direction in which the prism units are arranged coincides with the direction of the Y-axis, and (c) both surfaces of each prism unit are parallel to the
axis and the angle θ or -θ shown in the following formulas [1] and [2]
It is characterized by the fact that

However, δ is the smaller of the spread angle of the incident light beam or the spread angle (±δ) that can be used by a device that uses the output light beam, and δ minus θ.

n: refractive index of a transparent body The present invention uses a reflective curved surface or a lens to create a directional light beam, similar to the method described in Japanese Patent Application No. 106779/1982, and removes brightness irregularities through a uniformizing component. This is a luminous flux equalizing component used in the method described above, and has the feature of uniformizing the amount of light without impairing the beam properties of the luminous flux, similar to that method.

This feature is important for obtaining high efficiency, even in fiber optic light guides or slide projectors.
Light rays that spread beyond the aperture angle of the optical system installed later are not used and are lost, so although the light source does not need to be parallel light, it is desirable that the light beam has unidirectionality. .

[Operation] The present invention will be explained in detail using FIG. In FIG. 1, 1 is a plan view of both serrated transparent bodies of the optical component according to the present invention. Both of the serrated transparent bodies 1 are plate-shaped objects having prism units 30 arranged in a row on two opposing parallel surfaces. Then, one of the paired surfaces is the incident surface 20 of the light beam.
The other side is defined as the output surface 22. In the figure, the X-axis is perpendicular to the entrance surface 20 and the exit surface 22, the Z-axis is perpendicular to the thickness direction of the sawtooth transparent body, and the Y-axis is perpendicular to both the X-axis and the Z-axis.

Here, consider the light ray 4 that enters from the entrance surface 20 in parallel to the X-axis. On the incident surface 20, the surface forming an angle 〇 with the The plane parallel to the +0 plane of the incident plane will be called the +0 plane, and the plane parallel to the −θ plane will be called the 1θ plane. According to Snell's law, a ray of light incident on the +0 plane changes its direction by an angle α that satisfies Equation 0 due to refraction, and reaches the exit plane separated by L tan α in the Y-axis direction.

If this light ray hits the +0 plane, the light ray returns to the original state as a light ray 5 parallel to the X-axis and is emitted. In this way, it is incident on the +0 plane +
A ray of light emitted from the 0-plane, or similarly a ray of light that enters the 1-θ plane and exits from the 1-θ plane, is L tanα, −
The light is emitted with a deviation in parallel by Ltanα. Here, θ is determined by the above-mentioned formula 0. If it is taken to be equal to , then α=−〇, and all light parallel to the X axis will pass through either of the two optical paths mentioned above.

Furthermore, the incident angle of the light that reaches the surface 6 perpendicular to the Y-axis before reaching the output surface 22 is π/2-θ. Since n51n (-10,) = ncosθ0 (', 'n>1) holds from the equation 0 and the total reflection condition, the surface 6 is not in optical contact with other substances and is not in contact with the air layer. If so, it will be totally reflected and reach the exit surface. Also, if surface 6 is made into a reflective surface by metal vapor deposition, etc.,
Similar results can be obtained even if this surface is in contact with another substance or does not satisfy the total reflection condition.

In addition, if sufficient reflection cannot be obtained due to poor smoothness of the surface 6 or optical contact with other substances, 7° and 8° in Fig. 3 will disappear, and the vicinity of the side surface will be affected. Therefore, in such cases, it is recommended to discard the light near the sides and use only the areas with good uniformity.
Alternatively, it is necessary to take measures such as setting Ltanα to be larger than W/4. In any case, the efficiency decreases, so it is preferable to adopt a configuration that allows reflection from the sides as described above.

If the incident light that enters the entrance surface 20 has the light amount distribution shown in FIG. 2, the output light will have the light amount distribution 7 (
(Due to light rays entering the +0 plane and exiting from the +0 plane)
, light intensity distribution 8 (due to rays incident on the -θ plane and emitted from the -θ plane), light intensity distribution 7° (due to rays incident on the +0 plane and emitted from the -θ plane),
(due to light rays emitted from the -θ plane after being reflected by),
Light intensity distribution 8° (after entering the −θ plane and reflecting at the surface 6, +
The light amount distribution 9 is made uniform by combining the light rays emitted from the zero surface. In this case, it is clear that the parallelism of the incident light is not impaired.

As can be seen from Fig. 3, in order to obtain a luminous flux as wide as the width W of the exit surface 20, L (the distance between the entrance surface and the exit surface) should be selected so that L tanα = W/4. good. In other words, θ=θ. If so, then .

If the incident light is perfectly parallel light, the light intensity distribution will be 3 brism units.
However, since the present invention realizes uniformity of the light flux with a slight spread angle, it is actually possible to use the light at a predetermined distance from the exit surface. It is possible to remove the uneven light intensity with period T.If the distance is set as D, then D>T/lanδ...■.However, here, δ is the spread angle of the incident light flux, or the device that uses the output light flux. Represents the smaller of the available divergence angles.

Therefore, the smaller T is, the smaller D can be obtained, which is preferable for downsizing the device. It is not desirable to do so.

Also, the fact that the spread angle δ is not 0 means that the value of the refraction angle α has a corresponding spread, so θ=θ. Even so, there are light ray components as shown in rays 10 to 12 in Fig. 4, and strictly speaking they are not as shown in Fig. 3, but
θ Cape θ. If the divergence angle δ is too large (otherwise, the effect shown in Fig. 3 will be obtained), the uniformizing component of the present invention will work effectively (in order for δ to be smaller than θ, the incident surface, Most of the light rays at such a large angle that the light incident from one surface constituting the arbitrary prism unit 30 of the output surface is blocked by the concave apex angle of the other surface are the light rays l in FIG.
Since it takes an optical path such as O to 12, it is hardly an effective light beam.

Next, a method for determining the valid range of the value of θ will be explained.

In Figure 5, the light beam with a divergence angle δ at the incident plane has a refractive index n
If the spread angle becomes δ゛ when it enters the medium, then
δ° is expressed in the first approximation as follows.

sin (π/2−ψ)=nsin(π/2−φ),
COSψ=ncosφ,', sinψdψ=nsinφdφ,', dφ= (sinψ/n5inφ)dψδ' =
(sinψ/n5inφ)δ At this time, the angle ψ is θ. If it is equal to , then φ = 2ψ = 200, so dφ = dψ / 2ncos ψ ...O δ1 = δ / 2ncos ψ ... 0 Next, when the angle ψ is increased by Δψ as shown in Figure 6. think of. The bending angle of parallel light φ° is calculated using the formula 0: φ° = φ + Δφ = φ + Δψ / 2 n cos ψ = 2 ψ + Δψ
/2n cosψ =2(ψ+Δψ) −(2-1/2 n cosψ)
Δψ... O If Δψ is small, the spread angle within the medium is approximately equal to δ゛ in Equation 0. If δ° is larger than the second term on the right side of Equation 0,
It has a ray component that satisfies φ = 2 (ψ + Δψ) ... O within the spread angle. Since this component is the component that exhibits the effects of the present invention most efficiently, having this component is a condition for applying the present invention.

Therefore, δ'> (2-1/2n cos ψ) Δψ, °, Δψ × δ/(4 n cos ψ−1),, Δθ × δ/(4 n cos
θ. −1), “, Δθ × δ/ (1+8n”)””
-' O Formula 0 is derived from this.

This inference was made regarding the spread angle of the incident light, but if δ is the effective spread angle of the output light, exactly the same result will be obtained by tracking the line of sight at the exit surface.

The feature of the present invention is that the light beam incident perpendicularly to the incident plane is divided into beams whose optical axis is bent by angles α and −α at the incident plane, and parallel to the original axis at the exit plane at a certain distance. By returning the luminous flux to
This produces the same effect as if they were lined up. This homogenizes the luminous flux, but it also has the effect of expanding the luminous flux.

In FIG. 1, this effect is not affected by the period T (also called the prism pitch) of each prism unit 30 formed on the incident surface 20 and exit surface 22 of the light beam, and the angle formed by the prism unit 30 with the X axis. This can be achieved as long as θ is formed accurately. For example, as shown in FIG.
A configuration in which the length is twice as long as the period T2 on the second side can also be adopted.

Furthermore, as shown in FIG. 8, the deviation dy of each prism unit 30 between the entrance surface 20 and the exit surface 22 in the Y-axis direction does not pose a problem for the above-mentioned effect, and the positioning accuracy of the entrance surface and the exit surface is limited in manufacturing. There are benefits that are not required.

[Example] Hereinafter, the optical component for uniformizing the luminous flux according to the present invention will be described based on specific examples.

The light flux uniformizing component 15 according to the present invention is a laminated body of toothed transparent bodies 1 on both sides having the shape shown in FIG. 1, or a transparent body having a similar shape, and an example of the laminated body is shown in FIG. . This is an example in which two tooth-like transparent bodies 1 of the same shape and thickness d are aligned and stacked to a height H, and a transparent adhesive must be used. In addition, in the present invention, the overall shape is important, and it does not have to be a laminate, but a transparent body having the same shape as that shown in FIG. 9 may be integrally molded by injection molding or the like as shown in FIG. 10. They are functionally equivalent.

Further, FIG. 11 shows an embodiment in which the waveforms of the overlapping emission surfaces are stacked such that they are shifted by 1/2 period (T/2). The double-side toothed transparent bodies 1 stacked in this manner do not need to have the same shape, and may be a stack of prism units 30 with different periods T and phases. This condition holds not only between each laminated layer, but also between the entrance surface and the exit surface of one double-sided toothed transparent body l, as described above.

This is why the expression "a double-toothed transparent laminate or a transparent body having a shape similar to a laminate" is used in the present invention.

In this way, by laminating the tooth-shaped transparent bodies l on both sides with different periods T and phases of the prism unit 30, there is an effect that the above-mentioned light intensity unevenness with the period T is less likely to appear. If it is smaller than T, the formula 0 is replaced by formula (2) and becomes the condition under which light intensity irregularities with period T do not appear.

D>d/lan δ° . . . where δ” represents the smaller of the spread angles in the plate thickness direction that can be used by the device that utilizes the incident luminous flux or the emitted luminous flux.

The optical component 15 according to the present invention has the effect of making the light amount uniform only in the Y-axis direction, but when using the light source 13 in which the non-uniformity of the light amount is limited to the direction, the present invention can be adjusted as shown in FIG. However, in the case of a light source of 13° where the non-uniformity of the light amount is two-dimensional, it is necessary to use the present invention in two stages with the Y axis perpendicular to each other to achieve uniformity, as shown in Figure 13. .

Furthermore, if the light intensity non-uniformity of the light source is extremely large and the stage cannot sufficiently remove this non-uniformity, L ta
Sufficient uniformity can be achieved by arranging parts with different nα in multiple stages. The simple answer is step 1. ,ta
As nα,=W/4, m-th stage L mtanQ 1&
= W/2'''. Fig. 16 (E) shows an example of a three-stage configuration. Fig. 16 (A) to (D)
16(E) respectively show the light quantity distribution at the positions A to D in FIG. 16(E), and it can be seen that the more the number of stages increases, the more uniform the light quantity becomes.

In the present invention, when a light ray is incident on the surface of a prism, a portion of the light ray is reflected when the light ray exits from the surface of the prism, and the amount of transmitted light is reduced. This reflective surface is around 10 when n=1.5.
It will be about %. For example, in the configuration shown in FIG. 13, there are four such surfaces, and the loss due to this is about 40%.

To reduce this loss and increase efficiency, each prism surface may be coated with an antireflection coating that minimizes reflectance at a predetermined angle of incidence. It is also effective to lower the reflectance by thinly coating the material with a low refractive index material.

The ease of design and production is shown below, as well as the performance obtained.

Here, it is assumed that the type shown in Fig. 10 is used as shown in Fig. 13 to obtain a luminous flux of 3 cm in length x 4 cm in width, which is slightly larger than the film size, for a 35 mm slide projector.

First, as parts for uniformity in the vertical direction, W = 3 cm H = 4 cm Material is methacrylic (PMMA) resin, n = 1.49 Using the formula, θ = θ, = 26.5' From now on tan θ . = 0.50 and using the 0 formula, L =
W/2 = 1.5cm To make production easier, T = 2.0mm. Next, for the parts used for horizontal uniformization, θ and T are also set equal, so that W=4Cm H=3 cm, so L=W/2=2cm.

That's all for the design, and it's extremely simple. 13th
When using the configuration shown in the figure with the light intensity distribution shown in Fig. 14 as the incident light, the light intensity distribution of the output light will be as shown in Fig. 15,
It can be seen that sufficient uniformity has been achieved. In addition, the first
Figures 4 and 15 are examples of actual measurement of incident light and output light. It shows the light intensity distribution on separate straight lines.

Here, if the spread angle of the luminous flux is δ = 20°, then D>T/la
nδ = 5.5 mm, and the required length of this optical component in Fig. 9 is at least 1.5 + 2.0 + 0.55 = 4.05 cm,
Even if you allow some margin, less than 5 cm is sufficient.

As described above, the optical system using the present invention is extremely compact, and when optical systems with similar functions are constructed using relay capacitors, it is quite possible to combine them into a similar size.

As can be seen from the formula 00, the refractive index of the transparent material used in the present invention is preferable because it can be made smaller and more compact. As shown in FIG. 17, by using materials with high and low refractive indexes, further miniaturization can be achieved.

In Figure 17, n + = 1.49 n z
= 1.40, and the nl layer is sufficiently thinner than the n2 layer.

Following the design example above, θ=θ. = 26.5@, this is due to refraction at the boundary between the two materials. When W = 4 cm, it is possible to make it about 2 mm shorter than the design example from the 0 type.

Note that in FIG. 17, n2 is meaningless because it cannot be miniaturized unless it is smaller than n. Also, the larger the difference between nl and n2, the greater the effect of miniaturization, but if the difference is too large (then the total reflection condition of It needs to be a face.

[Effects of the Invention] As explained above, the optical component according to the present invention uniformizes the light intensity of a non-uniform light beam created by using a reflecting curved surface or a lens in the light source without impairing the beam properties. This makes it possible to easily produce a light source that provides a highly efficient and uniform luminous flux, and has a great practical effect.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the state of light rays passing through a rectangular brim-shaped transparent body with a pair of opposing sides formed in a serrated shape;
Figure 2 is a diagram showing the light quantity distribution of incident light, Figure 3 is a light quantity distribution diagram showing the principle of uniformity of light quantity, and Figure 4 is a diagram showing the light quantity distribution diagram showing the principle of uniformity of light quantity. Figures 5 and 6 are diagrams to explain the basis for deriving formula 0, respectively, and Figures 7 and 8 are diagrams showing that there are rays that pass through a different optical path than the rays. Figures 9 and 11 are diagrams showing the deformation of a shaped transparent body, Figures 9 and 11 are diagrams each showing an example of a laminate according to the present invention, and Figure 10 is a diagram showing an example of the same shape as the example in Figure 9, which is integrally molded. A diagram showing a transparent body, FIG. 12 is a diagram of an embodiment in which the present invention is applied to incident light having non-uniformity in light amount in only one direction, and FIG. 13 is a diagram showing an example in which the present invention is applied to incident light having non-uniformity in two dimensions. Diagram showing how to use when adapting, 1st
Figures 4 and 15 are diagrams showing the light intensity distribution of incident light and output light, respectively, Figures 16 (A) to (E) are diagrams each showing the effect of multi-stage formation, and Figure 17 is a diagram showing the miniaturization of the present invention. It is a figure showing an example. 1... Double serrated transparent body 2... -0 surface 3... +0 surface 6... Side surface 20... Incident surface 22... Output surface 30... Prism unit 13.13°. ...Light source 15... Optical component that homogenizes the luminous flux Agent Patent attorney Yuzuru Yamashita Figure Figure Figure Figure Figure Figure Figure

Claims (1)

[Claims] (1) A laminated double-serrated transparent body in which a plurality of prism units are formed on a pair of opposing surfaces, or a transparent body having a similar shape to the laminated body, (a) The pair of surfaces one is the incident surface of the light flux, the other is the exit surface, the X axis is perpendicular to the entrance surface and the exit surface, the Z axis is in the lamination direction of both the sawtooth transparent bodies, and the direction is perpendicular to both the X axis and the Z axis. When taking the Y axis, the ridge lines formed by both surfaces constituting each of the prism units are parallel to the Z axis, (b) the direction in which the prism units are arranged coincides with the direction of the Y axis, and (c) each of the above Both sides constituting the prism unit are each X
axis and the angle θ or -θ shown in the following formulas [1] and [2]
An optical component that uniformizes the luminous flux, characterized by the following: θ_o−δ/[(1+8n^2)^1^/^2]<θ<
θ_o+δ/[(1+8n^2)^1^/^2]...
[1] θ_o=COS^-^1 ([1+(1+8n^2
)^1^/^2]/[4n])... [2] However, δ is the spread angle of the incident light beam or the spread angle (±δ) that can be used by the device that uses the output light beam, whichever is smaller. , δ
<θ_on: refractive index of transparent body