JP5123098B2 - 1/2 wave plate - Google Patents

Description

The present invention relates to a half- wave plate having a function of rotating polarized light of linearly polarized incident light by 90 ° using a crystal which is a crystal that causes birefringence.

  In recent years, laser processing apparatuses are used for forming via holes in high-density mounting substrates. In such a laser processing apparatus, for example, various processing shapes can be obtained by simultaneously using laser beams having a plurality of wavelengths obtained by generating harmonics with respect to the fundamental wave (Patent Literature). 1). In this laser processing, as is well known, the polarization direction of linearly polarized laser light is controlled using a half-wave plate.

  The half-wave plate described above is generally composed of two quartz plates so as to withstand a laser having a high light output. The difference between the thicknesses of the two quartz plates is made to correspond to light having a desired wavelength. In this half-wave plate, the optical axes parallel to the principal surfaces of the two quartz plates are different from each other by 90 °, and the polarization direction of light perpendicularly incident on the principal surface of the quartz plate is the principal surface. It is rotated 90 ° in a parallel plane. Further, as is well known, by processing the quartz plate with higher accuracy so that the relationship between the optical axes of the two quartz plates is accurately 90 °, the target light is transmitted. The phase difference between the ordinary light and the extraordinary light is made closer to 180 °.

JP 2007-114520 A

  However, when laser beams having a plurality of wavelengths are used, a half-wave plate is required for each wavelength, which increases the number of parts. For example, when using laser light with three wavelengths, three half-wave plates obtained by bonding two quartz plates are required. Further, in Patent Document 1, by rotating a half-wave plate, one half-wave plate is made to correspond to a plurality of wavelengths of laser light. A rotating device for rotation is required. As described above, when the polarization states of the light sources having a plurality of wavelengths are controlled by the half-wave plate, there is a problem that the number of parts is increased.

  The present invention has been made to solve the above-described problems. The polarization state of a light source having a plurality of wavelengths is set to 1 without causing an increase in the number of components such as using a plurality of half-wave plates. An object is to enable control (change) by a / 2 wavelength plate.

The half- wave plate according to the present invention includes a first quartz component corresponding to a quartz plate having a thickness of 0.17 mm, a second quartz component corresponding to a quartz plate having a thickness of 0.255 mm, and a thickness of 0. A third crystal part corresponding to a quartz plate having a thickness of 0.34 mm and a fourth crystal part corresponding to a crystal plate having a thickness of 0.34 mm, the incident light incident direction being the Z axis, and polarization of the incident light When an XYZ orthogonal coordinate system is defined in which the direction is the X axis and the direction orthogonal to the X axis and the Z axis is the Y axis, the first, second, third, and fourth crystal components are Are arranged in parallel to the XY plane, and the plate thickness of the first, second, third and fourth crystal parts is a dimension in the Z-axis direction, and the first, second, third and fourth fourth crystal components, each said main surface in parallel to each other, from the incident side of the incident light said first crystal part, said second The crystal parts, the third crystal part, and the fourth crystal part are stacked in this order, and the optical axes of the first, second, third, and fourth crystal parts are the respective crystal parts. The angle of the optical axis of the first crystal component is 26 ° with respect to an arbitrary straight line assumed in the main surface of the first crystal component, and the second crystal component is parallel to the main surface. The angle of the optical axis of the quartz component is −43 ° with respect to the X-axis, the angle of the optical axis of the third quartz component is 66 ° with respect to the X-axis, and the fourth angle of the optic axis of the crystal part, you being a -87 ° with respect to the X-axis.

In the half- wave plate, the first crystal component and the third crystal component are configured by a crystal plate having a plate thickness of 0.17 mm, and the second crystal component is formed by a plate thickness of 0.255 mm. The fourth crystal component is formed of a crystal plate having a plate thickness of 0.34 mm.

  As described above, according to the present invention, the first crystal component corresponding to the crystal plate having a plate thickness of 0.17 mm, the second crystal component corresponding to the crystal plate having a plate thickness of 0.255 mm, and the plate thickness Since a third crystal component corresponding to a crystal plate having a thickness of 0.17 mm and a fourth crystal component corresponding to a crystal plate having a thickness of 0.34 mm are provided, a plurality of half-wave plates are used. An excellent effect is obtained in that the polarization state of the light sources having a plurality of wavelengths can be changed by the half-wave plate without causing an increase in the number of parts.

  Hereinafter, embodiments of the present invention (hereinafter referred to as “embodiments”) will be described with reference to the drawings.

First, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view showing a configuration of a half- wave plate according to an embodiment of the present invention. The half- wave plate in the present embodiment includes a crystal component (first crystal component) 101, a crystal component (second crystal component) 102, a crystal component (third crystal component) 103, and a crystal component ( 4th crystal component) 104. Each of the quartz parts 101 to 104 is composed of a quartz plate, each of which is arranged in a state in which the principal surfaces are parallel to each other, the optical axis is parallel to the principal surface, and each has a different optical axis.

  In FIG. 1, the polarization direction of the target incident light is the X axis, and the incident direction of the target incident light is the Z axis. When the main surfaces of the crystal plates constituting the crystal components 101 to 104 are arranged in parallel to the XY plane, the optical axes of the crystal plates constituting the crystal components 101 to 104 are arranged on the XY plane. It will be. Further, the plate thickness of the quartz plate constituting each of the quartz parts 101 to 104 is a dimension in the Z-axis direction.

In addition, in the half- wave plate in the present embodiment, the crystal component 101 corresponds to (corresponds to) a crystal plate having a plate thickness of 0.17 mm, and the crystal component 102 corresponds to a crystal plate having a plate thickness of 0.255 mm. The quartz plate 103 corresponds to a quartz plate having a thickness of 0.17 mm, and the quartz component 104 corresponds to a quartz plate having a thickness of 34 mm. For example, the crystal component 101 and the crystal component 103 are made of a crystal plate having a thickness of 0.17 mm, the crystal component 102 is made of a crystal plate having a thickness of 0.255 mm, and the crystal component 104 is made of a plate thickness of 0.34 mm. It consists of a quartz plate. These plate thicknesses are based on the relationship of plate thickness of crystal component 101: plate thickness of crystal component 102: plate thickness of crystal component 103: plate thickness of crystal component 104 = 2: 3: 2: 4 with 0.085 mm as a reference. It has become.

Here, the optical axes of the crystal components 101 to 104 are in different directions.
Assume that an arbitrary straight line is assumed in the XY plane, and the counterclockwise direction in the plane is “+ (plus)” and the clockwise direction is “− (minus)” on the basis of the arbitrary straight line. At this time, the optical axis of the crystal component 101 is in the direction of + 26 ° with respect to an arbitrary straight line. That is, the angle φ formed by the optical axis of the quartz part 101 and an arbitrary straight line is + 26 °. Similarly, the angle φ formed by the optical axis of the crystal component 102 and the X axis is −43 °, the angle φ formed by the optical axis of the crystal component 103 and the X axis is + 66 °, and the optical axis of the crystal component 104 And the X axis is -87 °.

In other words, when the crystal component 101, the crystal component 102, the crystal component 103, and the crystal component 104 are formed of a rectangular crystal plate in plan view, the optical of the crystal plate of the crystal component 101 is selected with respect to one side selected in the rectangle. The angle difference between the axes is + 26 °, the angle difference between the optical axes of the crystal plates of the crystal component 102 is −43 °, the angle difference between the optical axes of the crystal plates of the crystal component 103 is + 66 °, and the crystal plate of the crystal component 104 A half- wave plate may be configured with an optical axis angle difference of −87 °.

According to the half- wave plate according to this embodiment of the present invention configured as described above, with respect to light (laser light) of wavelengths 253 to 274 nm, 317 to 362 nm, 465 to 600 nm, and 1045 to 2000 nm, The phase difference can be in the range of 180 ° ± 5 °.

In the actual production of the half- wave plate, the above-described optical axis relationship is approximately established among the quartz component 101, the quartz component 102, the quartz component 103, and the quartz component 104 that have the above-described plate thickness relationships. In such a range, the optimum optical axis angular relationship may be obtained appropriately so that the phase difference with respect to each wavelength described above is in the range of 180 ° ± 5 °. As a result, the relationship between the angles may deviate within a range of ± 2 °, for example.

Next, FIG. 2 shows optical characteristics (wavelength dependence of retardation) of the half- wave plate according to the embodiment of the present invention. Note that this result is a simulation value using the rotation analyzer method, and there is no distinction between the left and right rotations of the polarization state due to the characteristics of the rotation analyzer method.
As shown in FIG. 2, the half- wave plate according to the embodiment of the present invention is based on 0.085 mm, the thickness of the crystal component 101: the thickness of the crystal component 102: the thickness of the crystal component 103: the crystal The thickness of the component 104 is 2: 3: 2: 4, and the actual phase difference 185 ° is 175 °. At this time, it can be confirmed that the phase difference is in the range of 180 ° ± 5 ° with respect to light (laser light) having wavelengths of 253 to 274 nm, 317 to 362 nm, 465 to 600 nm, and 1045 to 2000 nm.

  In such an embodiment, the quartz plates (quartz components) may be arranged in contact with each other or may be arranged apart from each other.

It is a perspective view which shows the structure of the half- wave plate which concerns on embodiment of this invention. It is a figure which shows the optical characteristic of the half- wave plate which concerns on embodiment of this invention.

  DESCRIPTION OF SYMBOLS 101 ... Crystal component (1st crystal component), 102 ... Crystal component (2nd crystal component), 103 ... Crystal component (3rd crystal component), 104 ... Crystal component (4th crystal component).

Claims (2)

A first quartz component corresponding to a quartz plate having a thickness of 0.17 mm;
A second quartz component corresponding to a quartz plate having a thickness of 0.255 mm;
A third crystal component corresponding to a crystal plate having a thickness of 0.17 mm ;
A fourth quartz component corresponding to a quartz plate having a thickness of 0.34 mm;
With
When an XYZ orthogonal coordinate system is defined in which the incident direction of incident light is the Z axis, the polarization direction of the incident light is the X axis, and the direction perpendicular to the X axis and the Z axis is the Y axis, the first, second, The main surfaces of the third and fourth crystal parts are arranged parallel to the XY plane, and the plate thicknesses of the first, second, third, and fourth crystal parts are in the Z-axis direction. Dimensions,
The first, second, third and fourth crystal parts are each in a state where the main surfaces are parallel to each other , and the first crystal part, the second crystal part, The third crystal component and the fourth crystal component are arranged in this order,
The optical axes of the first, second, third, and fourth quartz parts are parallel to the main surface in each quartz part,
The angle of the optical axis of the first crystal component is 26 ° with respect to an arbitrary straight line assumed in the main surface of the first crystal component,
The angle of the optical axis of the second crystal component is −43 ° with respect to the X axis,
An angle of the optical axis of the third crystal component is 66 ° with respect to the X axis,
The angle of the optical axis of the fourth crystal component, a half-wave plate, which is a -87 ° with respect to the X-axis. The half- wave plate according to claim 1,
The first crystal component and the third crystal component are composed of a crystal plate having a plate thickness of 0.17 mm,
The second quartz component is composed of a quartz plate having a thickness of 0.255 mm,
It said fourth crystal component, a half-wave plate, characterized in that it is composed of a quartz plate having a thickness of 0.34 mm.

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