JPH0640162B2 - Multi-function lens assembly - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a compound lens system in which a transparent substrate having a laminated structure is provided with portions having a lens function on both sides, and in particular, an image reading sensor of a facsimile apparatus or the like. And a compact and high numerical aperture lens system.

[Conventional technology]

Various information devices such as a reading sensor for a facsimile machine require a so-called microlens having a diameter of 1 mm or less.

Therefore, conventionally, as such a microlens, a flat lens shown in FIG. 5 is known.

In FIG. 5, reference numeral 1 is a parallel-plane transparent substrate made of a transparent material such as glass, and thin film portions 11 and 12 made of a suitable plastic material are provided on both surfaces thereof. A concentric grading is applied to the light transmitting portion in the central portion, whereby lens portions 111 and 121 made of Fresnel lenses are formed.
In FIG. 5, (a) is a convex lens system and (b) is a concave lens system, and in this case, R ₁ , h ₀ , h ₁ , h ₂ , R _2, etc. are arbitrarily designed according to the required light-collecting characteristics.

By the way, in order to obtain a lens system having a higher NA (numerical aperture) in such a flat lens, as shown in FIG. 6, the upper lens portion 111 and the lower lens portion 1 are used.
It is only necessary to reduce the light by both actions of 21 and increase the thickness h ₀ of the transparent substrate 1. The specifications of the lens at this time can be easily determined from the formula of the thick lens.

However, in the case of such a microlens using a flat plate-shaped lens, a photolithography process for semiconductor manufacturing is mainly used for manufacturing the microlens. Therefore, in the case of a low NA in which the thickness of the transparent substrate 1 is small, Although there is no particular problem, a lens having a large NA of the transparent substrate 1 and having a high NA makes the manufacturing process difficult and the manufacturing difficult.

Therefore, as such a plate lens having a high NA, two transparent substrates 1a and 1b are used as shown in FIG.
So-called laminated lenses have been conventionally proposed in which lenses 111 and 121 are formed on one of these surfaces, respectively, and these are bonded at a joint surface S. Examples thereof are, for example, Optical Technology Contact magazine, Vol. .23.No.10 (1985), 690 ~
See page 696.

[Problems to be solved by the invention]

In the above-mentioned conventional example, for the time being, although a laminated lens is disclosed, nothing is disclosed about a specific method or process for the adhesive structure, and characteristics such as transmittance and bonding strength and environmental resistance are not disclosed. However, due to lack of due consideration in practical use, such as the process of assembly, adjustment, etc., the optical function element such as a light modulator is sandwiched between two lenses and integrated. If you want to get a lens assembly,
There is a problem that it is difficult to maintain sufficient accuracy.

It is an object of the present invention to sufficiently address the above-mentioned problems of the prior art, to easily manufacture, and to apply a highly accurate multifunction lens assembly at low cost.

[Means for solving problems]

The above-mentioned object is to sandwich an optical functional element through a conductive film between the surfaces of the two metal-containing transparent substrates having the lens structure formed on one surface thereof, on which the lens structure is not formed, and electrostatically It is achieved by adhering and integrating.

[Action]

By heating the metal-containing transparent substrate and applying an electric field between it and the conductive film, metal ions contained in the substrate are dissociated and moved, and an interionic force is generated at the interface between the two. If cooled in this state, the metal ions are fixed and the interionic force is retained, so that they are firmly bonded. This is the principle of electrostatic adhesion, but since it is essential that the adherend surface be a flat mirror surface, it cannot be used for conventional spherical lenses. However, recently, a grating or a graded-index type flat lens is being developed, and if a conductive film is sandwiched on this plane, a plurality of flat lenses or lens array plates can be bonded at once by a dry process. Therefore, precise positioning and high strength bonding are possible.

If a conductive transparent film is used, the thickness thereof can be made extremely thin to 1 μm or less, so that a laminated lens having good transmittance can be obtained.

A high-performance lens assembly can be made by removing a part of the conductive film formed at the junction and forming a deflecting, dimming filter and a modulation function element in a region where light is transmitted.

〔Example〕

Hereinafter, the multifunctional lens assembly according to the present invention will be described with reference to the embodiments shown in the drawings. Prior to that, various laminated lenses to which the present invention is applied will be described.

First, FIG. 1 shows an example of the first lens.
Is a conductive film, and the others are the same as the conventional example shown in FIGS.

The conductive film 2 is formed of SnO ₂ (tin oxide), In ₂ O ₃ (indium oxide), Al (ammonium), or the like, which contains glass containing metal such as Na (sodium) or Mg (magnesium), plastic, etc. It is formed so as to be sandwiched between the two transparent substrates 1a and 1b made of the above material.

As shown in FIG. 1, the two transparent substrates 1a and 1b are stacked by sandwiching the conductive film 2 and then heated to a predetermined temperature, and the conductive film 2 is heated by a DC power source E having a predetermined voltage. Is a positive potential, and a voltage having a negative voltage on each of the substrates 1a and 1b is applied. As a result, the metal ions contained in each transparent substrate 1a, 1b dissociate and move, and an interionic force is generated at the interface between the two. Therefore, if the whole is returned to room temperature in this state, the metal ions are fixed, the interionic force is maintained, and the transparent substrates 1a and 1b are firmly bonded.

At this time, if the conductive film 2 is a transparent body such as SnO ₂ or In ₂ O ₃ , the film may be formed on the entire surface as shown in FIG.
When a metal film such as 1 is used, the film is formed only in the peripheral portion excluding the region through which the central tip penetrates, and only this portion is bonded.

Therefore, according to this example of the first lens, the strong adhesion between the two transparent substrates 1a and 1b can be obtained only by interposing the conductive film 2 which can be formed extremely thin with a thickness of 1 μm or less.
A flat lens having a high NA by laminating a plurality of transparent substrates can be easily manufactured by a photolithography process for semiconductor manufacturing.

Further, according to this first example of the lens, since it can be manufactured by utilizing the fine processing technology of photolithography, it is possible to easily mass-produce a lens or a lens array having a small size of 0.1 to 1 mmφ. In addition to facsimiles, they are promising as microlenses for information terminal equipment such as laser beam printers and optical heads.

By the way, in the above example of the first lens, the so-called Fresnel lens type microlens by forming the grating has been described, but the present invention shows that the refractive index distribution is obtained by the process of generating the metal ion concentration in the transparent substrate. It is also possible to use a so-called GRIN lens, which is formed so as to provide a lens function by this, and examples of the second and third lenses thus configured will be described with reference to FIGS. 2 and 3.

2 and 3, 2a is a conductive film made of an opaque material such as Al, 21 is an opening formed in the conductive film 2a, and 2b is a conductive film made of a transparent material such as SnO ₂ . It should be noted that the lens portions 111 and 121 are formed by a refractive index distribution in FIGS. 2 and 3.

First, in the example of the second lens shown in FIG. 2, first, the conductive film 2 having the opening 21 as shown in FIG.
a is provided on one surface of each transparent substrate 1a, 1b, and then
Predetermined metal ions are introduced from the opening 21 into the transparent substrate 1a,
1b, thereby forming a lens portion 111 or 121 having a refractive index distribution, and then removing the conductive film 2a as shown in FIG.

Next, as shown in FIG. 3C, a transparent conductive film 2b is formed on the surface of one of the transparent substrates, for example, 1b, and then electrostatically bonded and laminated as shown in FIG. To get a shaped lens.

In addition, in the example of the third lens shown in FIG.
The conductive film 2a having 1 is left as it is and electrostatically adhered. After the lens portions 111 and 121 are formed as shown in FIG. 7A, electrostatically adhered as shown in FIG. This is to obtain a laminated lens.

Incidentally, as such a GRIN lens, in addition to the above-described one in which the refractive index distribution is created by the difference in the metal ion concentration, a local residual stress is formed in the transparent substrate, whereby the refractive index distribution is It is also known that it is caused, for the present invention described below,
You may implement with such a lens.

Next, the embodiments of the present invention will be described. First, as is clear from the above description, in the prior art examples of the laminated lenses, conceptually, as shown in FIG. The flat plate lenses L1 and L2 are laminated as they are. In the figure, B is an interface (conductive film portion), I
Represents incident light and O represents emitted light.

On the other hand, in the embodiment of the present invention, as shown in FIG.
An optical functional element F is provided between the two flat plate lenses L1 and L2.
Is provided.

Here, B1 and B2 respectively represent an interface (conductive film portion). Therefore, in the multifunctional lens assembly according to this embodiment, the transparent substrate 1a and the transparent substrate 1b in FIG.
After the conductive film 2 is provided on each of them, the optical functional element F is sandwiched by these and electrostatically adhered to be integrated.

Here, as the functional element M, a deflection element, a filter,
A wavelength plate, an optical modulation element, or the like can be considered, and when the optical modulation element is used, the external signal M is given.

According to the embodiment of FIG. 4 (a), it can be used not only as a lens system but also as a unit having other optical processing functions, and the range of application can be expanded.

〔The invention's effect〕

As described above, according to the present invention, the flat lens can be firmly and precisely adhered by the electrostatic adhesion by the dry process without deteriorating the transmittance, and the small and high NA laminated lens of 1 mmφ or less is used. The multi-functional lens assembly can be easily obtained by a mass production process.

In other words, the conventional assembly in which the microlens and the optical functional element such as the light modulation element are integrated is assembled on the substrate surface together with the optical waveguide, etc. Was also difficult.

However, according to the present invention, since the microlens and the optical functional element such as the light modulation element are three-dimensionally integrated by electrostatic adhesion, high precision can be easily maintained by the mass production process, and the handling is easy. Since it is easy, it can be applied to a wide range of devices such as a light receiving portion of a facsimile, a writing / reading head in an optical recording device, and the like to promote their high performance.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first example of a laminated lens used in the present invention, and FIG. 2 is an explanatory view showing a second example of a laminated lens used in the present invention, and FIG. Is an explanatory view showing a third example of the laminated lens used in the present invention, and FIG. 4 is a conceptual diagram showing one embodiment of the multifunctional lens assembly according to the present invention in comparison with the laminated lens, FIG. 5 is a side sectional view showing an example of a flat lens, FIG. 6 is a side sectional view showing another example of the same flat lens, and FIG. 7 is a side sectional view showing a conventional example of a laminated lens. 1a, 1b ... Transparent substrate, 2 ... Conductive film, 11, 12 ...
... Thin film part, 111, 121 ... Lens part.

Claims (2)

[Claims] 1. An optical functional element is sandwiched between two surfaces of a metal-containing transparent substrate having a lens structure formed on one surface thereof, on which the lens structure is not formed, with an electrically conductive film interposed therebetween, and the static function is maintained. A multifunctional lens assembly characterized by being integrally formed by electroadhesion. 2. A multifunctional lens assembly according to claim 1, wherein the optically functional element is a light modulation element.