KR20020028264A - Optics system applying laser diode - Google Patents

Abstract

PURPOSE: An optical system adopting a laser diode is provided, which minimizes an optical loss by converting a laser beam into a circular one by installing a light source and a number of lenses in a housing. CONSTITUTION: A laser diode(21) emitting a laser beam(200) is installed as a light source. A semiconductor chip(21c) is attached on a side wall of a stem part, and a plurality of electrodes, a cathode(21a) and an anode(21b) are formed below the stem part. An output of the laser diode is 1.5 Watt, and its wavelength is 980 nanometer, and its vertical beam divergence is 48 degree and horizontal beam divergence is 12 degree. A collimating lens(22) is installed in the inside of the laser diode to collimate the laser beam from the laser diode. A focusing lens(23) is installed in front of the collimating lens, to focus the collimated laser beam. A beam shaping lens(24) is installed in front of the focusing lens to convert the laser beam into a circular beam. And an optical fiber(25) is installed in front of the beam shaping lens.

Description

Optical system employing laser diodes {Optics system applying laser diode}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system, and more particularly, to an optical system employing a laser diode in which a plurality of lenses are attached in front of a laser diode in a housing to improve light efficiency.

In general, the laser diode emits an elliptical laser beam because its vertical axis is relatively large compared to the horizontal axis, and thus, collimating and focusing the beam using a plurality of lenses to reduce the optical loss. Will be delivered.

1 shows an optical system employing a conventional laser diode.

Referring to the drawings, a conventional optical system includes a laser diode 11, which is a light source for emitting a laser beam 100, a collimating lens 12 installed in front of the collimating lens 12 for collimating the laser beam 100, and A plurality of beam shaping lenses 13 and 14 for shaping the collimated laser beam 100, a focusing lens 15 for focusing the shaped laser beam 100, The optical fiber 16 to which the focused laser beam 100 is incident is included.

The optical system has an elliptical shape instead of a circular shape because the divergence angles of the vertical axis and the horizontal axis of the laser beam 100 emitted from the semiconductor chip are different due to the optical characteristics of the laser diode 11. Accordingly, when using a single lens (cylindrical lens) or a spherical lens (spherical lens) is often used, the light efficiency is typically about 60 to 65 percent.

Therefore, in order to improve the light efficiency, as shown in FIG. 1, a compound lens in which two or more single lenses are combined is used. In this case, the use of a plurality of lenses, the light efficiency is relatively higher than when using a single lens, while the length of the length of the lens is used to increase the overall size of the optical system, the weight is increased, the price is also increased Act as a factor.

The present invention has been made to solve the above problems, to provide an optical system that employs a light source and a plurality of lenses in the housing to adopt a laser diode that transforms the laser beam into a circular shape to minimize light loss. There is this.

1 is a configuration diagram schematically showing an optical system employing a conventional laser diode,

Figure 2 is a schematic diagram showing an optical system employing a radar diode according to an embodiment of the present invention.

<Brief description of symbols for the main parts of the drawings>

11,21 ... laser diode 12,22 ... collimating lens

13,14 ... 24 Beam Orthopedic Lens 15,23 ... Focusing Lens

16, 25 Optical fiber 21a Cathode

21b ... anode 21c ... semiconductor chip

26 Fiber optic fixture 27 Epoxy

28. Housing

In order to achieve the above object, the optical system employing a laser diode according to an aspect of the present invention,

A laser diode emitting a laser beam;

A collimating lens positioned in front of the laser diode to collimate the laser beam;

A focusing lens positioned in front of the collimating lens to focus the collimated laser beam;

A beam shaping lens positioned in front of the focusing lens to transform the elliptical laser beam into a circle;

An optical fiber to which a laser beam is incident from the beam shaping lens; And

And a housing unit in which the laser diode, collimating lens, focusing lens, beam shaping lens, and optical fiber are continuously installed therein.

In addition, the beam shaping lens is characterized in that located on the light incident surface of the optical fiber.

Furthermore, the collimating lens is a spherical lens, the focusing lens is a flat convex lens, and the beam shaping lens is a cylindrical lens.

Hereinafter, an optical system employing the laser diode of the present invention will be described in detail with reference to the accompanying drawings.

2 shows an optical system employing a laser diode according to an embodiment of the present invention.

Referring to the drawings, the laser diode 21 is provided in the optical system as a light source for emitting the laser beam 200. As is well known, the laser diode 21 has a semiconductor chip 21c attached to one side wall of the stem portion. And the cathode 21a which is a some electrode, and the anode 21b are taken out under the stem part.

The laser diode 21 has an output of 1.5 watts, a wavelength of 980 nanometers, a beam divergence of 48 degrees vertically, and 12 degrees horizontally.

A barrel is installed in front of the laser diode 21, and a collimating lens 22, which is a spherical lens, is installed in a space provided therein. The collimating lens 22 collimates the laser beam 200 emitted from the laser diode 21. The lens 22 has a diameter of 2 millimeters and a refractive index of about 1.85. In addition, the collimating lens 22 preferably has a large numerical aperture, and the focal length is relatively short at 1.1 millimeters.

The front surface of the collimating lens 22 is provided with a focusing lens 23, which is a plano-convex lens. The focusing lens 23 focuses the collimated laser beam 200 from the collimating lens 22 and shortens the overall length of the optical system. The focusing lens 23 has a diameter of 3 millimeters and preferably has a refractive index of about 1.49.

On the front side of the focusing lens 23, a beam shaping lens 24, which is a cylindrical lens, is provided. The beam shaping lens 24 is an ellipse in which a laser beam 200 focused from the focusing lens 23 is formed with a longitudinal axis relatively larger than a horizontal axis due to the characteristics of the laser diode 21. Accordingly, light loss can be reduced. The beam shaping lens 24 has a diameter of 200 micrometers and a refractive index of 1.457. In addition, the numerical aperture is about 0.22.

An optical fiber 25 is installed in front of the beam shaping lens 24. The optical fiber 24 is focused to a point where the laser beam 200 emitted from the beam shaping lens 24. The optical fiber 24 is about 100 micrometers in diameter of the core, the aluminum is coated on the outer peripheral surface of the core. The optical fiber 24 has a refractive index of 1.49 and a numerical aperture of about 0.37.

The optical fiber 24 is wrapped by a fiber fixture 26.

Here, the above-described laser diode 21, collimating lens 22, focusing lens 23, beam shaping lens 24, and optical fiber 25 are continuously installed in the housing portion 28. have. Reference numeral 27 is an epoxy for fixing the fiber fixture 26 in the housing portion 28.

In this way, the optical system installed in one housing portion 28 has the laser beam 200 emitted from the laser diode 21 collimated and focused through the collimating lens 22 and the focusing lens 23, and the beam shaping lens It is deformed into a circle from 24 to be delivered to the core of the optical fiber 25.

Testing with these optical systems has shown that the coupling efficiency has been measured at approximately 70-75 percent, which is 10 percent better than conventional optical systems. In addition, assuming that the light loss at the surface of each lens is 3 percent per side, anti-reflection coating on the lens surface will increase the light efficiency by at least 10 percent.

As described above, the optical system employing the laser diode of the present invention can obtain the following effects.

First, by providing a laser diode and a plurality of lenses continuously in one housing portion, the overall size of the optical system can be significantly reduced, and the weight can be reduced.

Second, by placing a beam shaping lens that transforms the elliptical laser beam into a circular shape on the incident surface of the optical fiber, the light efficiency and assembly performance are improved.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (3)

A laser diode emitting a laser beam; A collimating lens positioned in front of the laser diode to collimate the laser beam; A focusing lens positioned in front of the collimating lens to focus the collimated laser beam; A beam shaping lens positioned in front of the focusing lens to transform the elliptical laser beam into a circle; An optical fiber to which a laser beam is incident from the beam shaping lens; And And a housing part in which the laser diode, collimating lens, focusing lens, beam shaping lens, and optical fiber are continuously installed therein. The method of claim 1, The beam shaping lens is an optical system employing a laser diode, characterized in that located on the light incident surface of the optical fiber. The method of claim 1, And said collimating lens is a spherical lens, said focusing lens is a flat convex lens, and said beam shaping lens is a cylindrical lens.