Complex lens

An embodiment of a complex lens (1) includes a central substrate (10), two opposite glass layers (12), and two opposite IR-cut layers (13). The substrate is made of transparent plastic, such as polycarbonate or polymethyl methacrylate. The glass layers are deposited on opposite surfaces of the substrate. The IR-cut layers are deposited on surfaces of the glass layers. The substrate has a spherical or an aspheric surface. The IR-cut layers have a function of filtering infrared rays, thereby improving the image-forming quality of the complex lens. The substrate is typically made of polycarbonate or polymethyl methacrylate. The glass layers are typically made of ZrO2—Y2O3 or SiC. Each IR-cut layer includes a plurality of films of Ti2O3 and SiO2.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to optical lenses, and more particularly to a complex optical lens.

2. Related Art

Currently, digital camera modules are included as a feature in a wide variety of portable electronic devices. Most portable electronic devices are becoming more miniaturized over time, and digital camera modules are correspondingly becoming smaller. Nevertheless, in spite of the small size of contemporary digital camera modules, consumers still demand excellent imaging. The image quality of a digital camera is mainly dependent upon the optical elements of the digital camera module.

Aspheric lenses are very important elements in a typical digital camera module. An aspheric lens can easily focus an image on an imaging point, because the aspheric lens can attain different refractive indexes via the selection of different materials and profiles for the aspheric lens. Therefore, an aspheric lens can avoid many of the image-forming problems of spherical lenses. In addition, with a single aspheric lens, the number of lens pieces in a camera is reduced. Thus the camera can have a reduced size. Two or more aspheric lenses are used in some cameras for high-quality image forming. Contemporary aspheric lenses are essentially made of glass or plastic.

Glass aspheric lenses are generally manufactured by way of glass molding. A glass molding machine operates at a high temperature and high pressure during the glass molding process. Therefore, core inserts are needed, and these must be accurately designed and manufactured. The core inserts should have excellent chemical stability in order not to react with the glass material. In addition, the core inserts also should have enough rigidity and excellent mechanical strength in order not to be scratched. Furthermore, the core inserts should be impact-resistant at high temperatures and under high pressures. Moreover, the core inserts should have excellent machinability in order that they may be machined precisely and easily to form the desired optical surfaces. Finally, the core inserts should have a long working lifetime so that the cost of manufacturing aspheric lenses is kept to a minimum. However, a typical contemporary core insert generally has a short working lifetime, which escalates the cost of producing aspheric lenses.

Plastic aspheric lenses are generally manufactured by way of injection molding. Though the cost of plastic aspheric lenses is relatively low, a plastic aspheric lens has a low image-forming quality compared to a glass aspheric lens. This difference in quality is due to the transparent quality of plastic being less than that of glass.

What is needed is an optical lens which has a lower cost and a better image-forming quality.

SUMMARY

A complex lens includes a substrate, a glass layer, and an IR-cut (infrared-cut) layer. The substrate is made of transparent plastic, such as polycarbonate or polymethyl methacrylate. The glass layer is deposited on a surface of the substrate. The IR-cut layer is deposited on a surface of the glass layer. The substrate has a spherical or an aspheric surface. The substrate comprises a material selected from the group consisting of polycarbonate and polymethyl methacrylate. The glass layer comprises a material of ZrO2—Y2O3or SiC. The IR-cut layer comprises a plurality of films of Ti2O3and SiO2. In a preferred embodiment, the complex lens includes a central substrate, two opposite glass layers, and two opposite IR-cut layers.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring toFIG. 1, in a preferred embodiment of the present invention, a complex lens1includes a central substrate10, two opposite glass layers12, and two opposite IR-cut layers13.

The substrate10is made of a transparent plastic material. The transparent plastic can be polycarbonate or polymethyl methacrylate. The substrate10has a concave surface and a convex surface, and preferably has a substantially uniform thickness. The concave surface can be either a spherical surface or an aspheric surface, and the convex surface can be either a spherical surface or an aspheric surface. The glass layers12are made of a glass material, such as ZrO2—Y2O3or SiC. The IR-cut layers13are each made of a plurality of complex films of Ti2O3and SiO2. A preferred number of complex films of Ti2O3and SiO2is in the range of 25-35.FIG. 2shows preferred thicknesses of the complex films. The glass layers12are deposited on two opposite surfaces of the substrate10, and the IR-cut layers13are deposited on surfaces of the two glass layers12respectively. The glass material has better transparency than the plastic material. In the preferred embodiment, the glass material is comprised of ZrO2—Y2O3or SiC, each of which has a low thermal expansion coefficient. The IR-cut layers13can filter out infrared rays that may diminish the image-forming quality of the complex lens1.

It is understood that in an alternative embodiment, the complex lens can have only one glass layer12, and one IR-cut layer13deposited on a surface of the glass layer12.

Referring toFIG. 1, a method for manufacturing the complex lens1comprises the steps of:

providing an injection mold, the injection mold having a spherical or an aspheric surface;

injecting transparent plastic into the injection mold, and forming a substrate10having a spherical or an aspheric surface at either or both of opposite sides thereof, the transparent plastic being polycarbonate or polymethyl methacrylate;

depositing a glass layer12on each of two opposite surfaces of the substrate10in a vacuum chamber by means of sputtering, the glass layers12being made of ZrO2—Y2O3or SiC; and

depositing IR-cut layers13on the surfaces of the glass layers12in a vacuum chamber by means of sputtering, the IR-cut layers13each having a plurality of complex films of Ti2O3and SiO2.

The glass layers12and the IR-cut layers13can also be deposited by other methods of vacuum deposition, such as physical vapor deposition, chemical vapor deposition, or vacuum evaporation.