JPH03201488A - Optical element - Google Patents

Abstract

PURPOSE:To offer an optical element, where an incident light is small in attenuation and the positional adjustment of a photodetective element on the basis of the position of a lens is not required, by a method wherein the photodetective element is arranged on the same plane of a substrate on which a plate lens is formed. CONSTITUTION:A Fresnel lens 2 is formed in an integral structure with a board 1 and has such a periodic structure of concentric circle that it becomes gradually small in period of grating starting from the center of a lens toward the outside, and the grating is brazed. Photodetective elements 3A and 3B are arranged at an upper part and a lower part which sandwiches the Fresnel lens 2 between them on the face of the board 1 where the Fresnel lens 2 has been formed. As mentioned above, a plate lens and photodetective lenses are provided on the same plane, so that the lenses can be formed thin. Light rays incident on the photodetective element are prevented from being attenuated, because they are not required to penetrate through a board, so that a photodetective element is not required to be so high in sensitivity.

Description

[Detailed description of the invention] Background of the invention Technical field The present invention relates to an optical element including a flat lens.

Prior art and its problems Examples of conventional optical elements constructed by combining a flat lens and other optical components are shown in FIGS. 6 to 8. In FIG. 6, one side of the transparent substrate 11 is covered with Fresnel.
A lens 12 is formed.

A light receiving element 13 is provided on the other surface. The incident light is focused by the Fresnel lens 12 and received by the light receiving element i3. In FIG. 7, a Fresnel lens 12 is formed on one surface of a transparent substrate 11, and a light emitting element 14 is provided on the other surface. The light emitted from the light emitting element 14 is collimated by the Fresnel lens 12 and projected.

In FIG. 8, two Fresnel lenses 12A and 12B are integrally formed on one surface of a transparent substrate 11, and a light emitting element 14 and a light receiving element are also formed on the other surface corresponding to each Fresnel ψ lens 12A and 12B. An element i3 is provided.

The light emitted from the light emitting strand 14 is collimated by one Fresnel lens 12A and projected onto the object 15. The reflected light from the object 15 is collected by the other Fresnel lens 12B and received by the light receiving element 13. As a result, the presence or absence of the object 15 is detected, optical information from the surface of the object 15 is collected, and the like.

In such a conventional optical element, since the light receiving element 13 is provided on the surface opposite to the surface of the substrate 11 on which the Fresnel lens 12.12B is formed, the incident light received by the light receiving element 13 is Since the light always passes through the substrate 11, the light is attenuated. The light emitted from the light emitting element 14 also passes through the substrate 11 and is emitted while being attenuated in the same way. Further, the light receiving element 13 and the light emitting element 14 must be provided with accurate position adjustment with respect to the corresponding Fresnel lenses 12.12A and 12B.

Furthermore, especially in the optical element shown in FIG.
This is because the light may be received by 3.

There is a problem in that this becomes noise light and its reliability decreases.

SUMMARY OF THE INVENTION Purpose of the Invention It is an object of the present invention to provide an optical element that does not cause attenuation of incident light received by a light receiving element and does not require position adjustment of the light receiving element based on the lens position. purpose.

Structure and Effects of the Invention The optical element according to the present invention is characterized in that a light receiving element is disposed on the surface of a substrate having a flat lens, on which the flat lens is formed.

Flat lenses include Fresnel lenses, gradient index lenses,
There are convex lenses, etc. In addition, the light receiving element is a photodiode,
Includes photodiode arrays, image sensors (CCD, etc.), etc.

According to this invention, since the flat lens and the light receiving element are on the same plane, the optical element can be made thinner. Furthermore, since the incident light received by the light receiving element does not pass through the substrate, it is not attenuated, and the light receiving element does not necessarily have to be highly sensitive.

Furthermore, since there is no need to adjust the position of the light receiving element to match the optical axis of the flat lens, manufacturing and adjustment are easy.

Even when the optical element according to the present invention is provided with a light emitting element,
The light receiving element is highly reliable because it does not receive reflected light (noise light) from the transparent substrate.

DESCRIPTION OF THE EMBODIMENTS FIGS. 1A and 1B show a first embodiment of the present invention. FIG. 1(A) is a front view, and FIG. 1(B) is a sectional view taken along line II in FIG. 1(A). fresnel
The lens 2 is formed integrally with the substrate 1, and has a concentric periodic structure in which the period of the grating becomes smaller from the center of the lens toward the outside, and the grating is blazed. Further, on the surface of the substrate 1 on which the Fresnel lens 2 is formed, light receiving elements 3A and 3B are arranged at upper and lower positions with the Fresnel lens 2 in between.

The light receiving cables 3A and 3B are photodiodes.

Examples include image sensors such as photodiode arrays and CCDs.

A standby for the Fresnel lens 2 is prepared in advance, and using this standby, the substrate 1 and the Fresnel lens 2 can be integrally formed by resin injection molding, molding using UV resin, or the like. In this case, the light receiving elements 3A and 3B may be manufactured by depositing amorphous Si (α-5i), CdS, etc. on the substrate 1, or separately prepared light receiving elements may be attached to the substrate 1. .

Further, the substrate 1 is a semiconductor substrate, and p
The light receiving elements 3A and 3B can also be manufactured by forming an n-junction. In this case, by filling the space between the semiconductor substrate and the standber with resin, it is possible to make the Fresnel lens 2 by resin molding on the semiconductor substrate, or it is possible to make a separately manufactured Fresnel lens on the semiconductor substrate. It may be attached to.

FIGS. 2A and 2B show a second embodiment. FIG. 2(A) is a front view, and FIG. 2(B) is a sectional view taken along the line ■-■ in FIG. 2(A). In this figure, the same components as those shown in FIGS. 1(A) and 1(B) are designated by the same reference numerals, and the description thereof will be omitted. Figure 2 (A), (B
The optical element shown in ) is constructed by disposing one light receiving element 3A on the surface of the substrate 1 on which the Fresnel lens 2 is formed.

FIGS. 3(A) and 3(B) show a third embodiment. FIG. 3(A) is a front view, and FIG. 3(B) is a sectional view taken along the line ■-■ in FIG. 3(A). In this figure, the same components as those shown in FIGS. 1(A) and 1(B) are designated by the same reference numerals, and the description thereof will be omitted. Figure 3 (A), (B
The optical element shown in ) is constructed by disposing an annular light receiving element 3C so as to surround the Fresnel lens 2 on the surface of the substrate 1 on which the Fresnel lens 2 is formed.

FIGS. 4 and 5 show examples in which optical sensors are constructed using optical elements.

In FIG. 4, the same optical elements as shown in FIGS. 2(A) and 2(B) are used. A light emitting element 4, such as a light emitting diode, a laser diode, etc., is arranged behind this optical element.

The light emitted from the light emitting element 4 passes through the substrate 1, is collimated or focused by the Fresnel lens 2, and is irradiated onto the object 5. The reflected light from the object 5 is received by the light receiving element 3 arranged on the substrate 1. Since the light receiving element 3 is disposed on the surface of the substrate 1 on which the Fresnel lens 2 is formed, the light reflected by the substrate 1 is not received.

The S/N ratio improves and reliability increases.

In FIG. 5, a light emitting element 4 is arranged on the optical axis of the Fresnel lens 2 on the surface of the substrate 1 opposite to the surface on which the Fresnel lens 2 is formed. The light emitting element 4 is fixed to the substrate 1 by adhesive. By doing so, the optical sensor can be made smaller. Furthermore, since all the elements are provided on the substrate 1, environmental resistance is improved.

In the above-mentioned embodiment, an example was explained in which a Fresnel lens was used as the flat lens.

It goes without saying that the present invention can be applied to other flat lenses, such as gradient index lenses and plano-convex lenses.

[Brief explanation of drawings]

FIGS. 1(A) and 1(B) show an embodiment of the present invention, where (A) is a front view and FIG. 1(B) is an I-I in FIG. 1(A).
It is a sectional view along a line. FIGS. 2 and 3 show other embodiments. Figures 2 (A) and (B) show the arrangement of one light-receiving element, where (A) is a front view and (B) is the - of Figure 2 (A).
■It is a sectional view along the line. Figures 3 (A) and (B) show annular light-receiving elements arranged around the lens; (A) is a front view, and (B) is a cross section taken along the line ■-■ in Figure 3 (A). It is a diagram. FIGS. 4 and 5 are cross-sectional views showing examples of optical sensors constructed using optical elements. 6 to 8 show conventional examples, and FIG. 6 is a sectional view showing an example in which light receiving elements are arranged. FIG. 7 is a sectional view showing an example in which light emitting elements are arranged, and FIG. 8 is a sectional view showing an example applied to object detection. Fig. 4 1...Substrate. 2... Fresnel lens. 3... Light receiving element. 4... Light emitting element. that's all

Claims (1)

[Claims] An optical element in which a light receiving element is disposed on a surface of a substrate having a flat lens, on which the flat lens is formed.