JP2000009932A - Polarizing prism and polarizing exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing prism, which copes with high optical power and has a large allowable angle, and to provide a polarizing exposure device which utilizes the prism and has high light utilization efficiency. SOLUTION: The optical axes of first and second prisms 1 and 2 are rotated by 90 degrees with respect to an optical axis and a narrow angle α1 on a light incident surface B and a narrow angle βon a light emitting surface C of the prism 2 are set so that the angles α1 and β are located on the same side on a plane F. Then, a surface having an angle γ is provided on a third prism 3 so that the light incident angle on the prism 1 and the light emitting angle from the prism 3 are made equal with respect to P polarized light beams.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing prism that can withstand high light power and has a large allowable incident angle, and a polarizing exposure apparatus using the polarizing prism and having high light use efficiency.

[0002]

2. Description of the Related Art As a conventional polarizing prism, for example,
There is a double Gran tailor prism. FIG. 5 shows a basic configuration diagram of the double Glan-Taylor prism 100. In FIG. 5, the first prism 101 is formed of calcite having birefringence or the like, has a trapezoidal cross-sectional shape having a plane H at an angle α with respect to a plane F including the optical axis.
The optical axis of the prism is set perpendicular to the plane F (the direction of the arrow X in the figure). The second prism 102 is made of an optical material having the same birefringence and optical axis direction as the first prism 101, and has a triangular cross section having two planes I and J at an angle α with respect to the plane F. The third prism 103 is also the first
It is made of an optical material having the same birefringence and optical axis direction as the prism 101, has a trapezoidal cross section having a plane K at an angle α with respect to the plane F, and the optical axis of the third prism is the first prism.
It is in the same direction as the prism 101.

[0003] The polarizing prism 10 constructed as described above
The operation of 0 will be described below. The polarizing prism 100 separates light having a high extinction ratio by utilizing the fact that the critical angle of total reflection is different between ordinary light and extraordinary light in the birefringent material. That is, when light first enters the first prism 101, the light is separated into extraordinary light (P-polarized light: perpendicular to the plane F) and ordinary light (S-polarized light: perpendicular to the optical axis and parallel to the plane F). Go forward. By setting the angle α to the angle at which the S-polarized light is totally reflected, the S-polarized light is totally reflected by the air gap between the first prism 101 and the second prism 102, and P
Polarized light is transmitted. As described above, light transmitted through the polarizing prism is only P-polarized light, and light with a high extinction ratio can be obtained. In addition, since the air gap is provided, it can withstand a light source having high energy. Also,
The feature of the double Glan tailor is that by providing the third prism 103, it is possible to obtain a target characteristic with respect to the incident angle θ.

[0004]

However, the conventional polarizing prism shown in FIG. 5 has the following problems.
FIG. 6 shows the polarizing prism shown in FIG.
789, an extraordinary light refractive index: 1.613, α: 56 °) and the transmittance of P-polarized light. As shown in FIG. 6, this polarizing prism has a transmittance only at an incident angle of ± 7 degrees. Thus, the usable incident angle range (hereinafter, referred to as allowable angle)
However, when it is small, the following problems occur. When a light source that cannot be said to be a point light source such as a mercury lamp is used, perfect parallel light cannot be produced like a laser. For this reason, when the allowable angle is small, light having a large incident angle is also generated for this angle, and there is a problem that such light cannot be transmitted and the light use efficiency is deteriorated. SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a polarizing prism that can withstand high light power and has a large allowable angle and a polarization exposure apparatus using the polarizing prism and having high light use efficiency.

[0005]

In order to solve the above problems, a polarizing prism of the present invention has a light exit surface A having a predetermined narrow angle α ₁ with respect to a plane F including an optical axis. A first prism made of a birefringent material whose optical axis is the direction of the P-polarized light component with respect to the exit surface A, a light incident surface B parallel to the light exit surface A of the first prism, and a plane F including the optical axis. A light exit surface C at a predetermined angle β with respect to the first and second surfaces B, C, and the first axis having the S-polarized light component direction with respect to the optical axis.
The second made of a material having the same birefringence as the prism
A prism, a light incident surface D parallel to the light exit surface C of the second prism, and a light exit surface E at an angle γ with respect to a plane F including the optical axis; A third prism made of a material having the same birefringence as the first prism having the component direction as an optical axis;
The angles α ₁ and β in the prism are angles on the same side with respect to the plane F, and the angles β and γ in the third prism are angles on the same side with respect to the plane F. , The angle γ is set such that the angle of incidence of the P-polarized component light on the first prism along the optical axis is equal to the angle of emergence from the third prism.

Further, in order to solve the above-mentioned problems, the present invention provides a polarization exposure apparatus using the above-described polarizing prism, and a light source for causing light within a predetermined incident angle range to be incident on the polarizing prism. It is characterized in that it comprises a selective light transmitting means for transmitting only the light emitted from the polarizing prism within a predetermined angle range out of the light emitted from the polarizing prism.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a basic configuration diagram of a polarizing prism according to a first embodiment of the present invention.

In the polarizing prism 10 shown in FIG. 1, the first prism 1 has a trapezoidal cross section having a light exit surface A at a predetermined angle α ₁ with respect to a plane F including the optical axis. It is composed of a birefringent material (calcite or the like) having the P-polarized component direction as the optical axis. The second prism 2
The first prism 1 has a triangular cross section having a light incident surface B parallel to the light exit surface A and a light exit surface C at a predetermined angle β with respect to a plane F including the optical axis. It is made of a material having the same birefringence as the first prism 1 having the S-polarized component direction as the optical axis (the direction in which the optical axis of the first prism 1 is rotated by 90 degrees around the optical axis). The third prism 3 has a trapezoidal cross section having a light incident surface D parallel to the light exit surface C of the second prism and a light exit surface E at a predetermined angle γ with respect to a plane F including the optical axis. P for both sides D, E
It is made of a material having the same birefringence as the first prism 1 whose polarization component direction is the optical axis (the same direction as the first prism 1).

Here, the angle α ₁ in the second prism is set.
And the angle β are angles on the same side with respect to the plane F, and the angles β and γ in the third prism are angles on the same side with respect to the plane F. The angle γ of the third prism 3 is set so that the outgoing angle is equal to the incident angle with respect to the P-polarized light (perpendicular to the plane F). Further, the angles α ₁ , β, and γ are set so that the exit angle of the P-polarized light exiting the third prism 3 and the exit angle of the S-polarized light do not overlap.

The polarizing prism 10 constructed as described above
The operation will be described below. When light enters the first prism 1, the light travels in the form of extraordinary light (P-polarized light: perpendicular to the plane F) and ordinary light (S-polarized light: perpendicular to the optical axis and parallel to the plane F). Outgoing surface A of this first prism 1
Is different between P-polarized light and S-polarized light due to birefringence. In the second prism 2, since the optical axis of the first prism 1 is rotated by 90 degrees about the optical axis, the P-polarized light incident on the incident surface B of the second prism 2 is ordinary light, and the S-polarized light is extraordinary light. It means that. Next, since the exit angle from the exit surface C of the second prism 2 is further different between the P-polarized light and the S-polarized light, the traveling directions of the P-polarized light and the S-polarized light are greatly shifted. Since the optical axis of the third prism 3 is the same as that of the first prism 1, the P-polarized light incident on the incident surface D of the third prism 3 is extraordinary light, and the S-polarized light is ordinary light.

The angle γ of the exit surface E of the third prism 3 is P
Since the exit angle of the polarized light from the exit surface E with respect to the optical axis is set to be the same as the incident angle with respect to the optical axis to the first prism 1, the exit angle of the P-polarized light is equal to the incident angle. On the other hand, the exit angle of the S-polarized light from the third prism is significantly different from that of the P-polarized light. FIG. 2 shows an ordinary light refractive index of 1.7.
89, extraordinary light refractive index: 1.613, α ₁ : 56 ° β: 6
The relationship between the incident angle and the transmittance when 6 ° and γ: 72 ° is shown. FIG. 3 shows the relationship between the incident angle and the outgoing angle.

In FIG. 2, the range in which the P-polarized light can be transmitted is about ± 12 degrees, which is much wider than the conventional ± 7 degrees. However, as can be seen from FIG. 2, S-polarized light has also been transmitted, while P-polarized light has an emission angle substantially equal to the incident angle, whereas S-polarized light has an approximate emission angle = incident angle + 2.
It may be regarded as a relationship of six degrees. At this time, if the incident angle is in the range of ± 12 degrees, the emission angle of P-polarized light is in the range of ± 12 degrees, and S
The polarized light becomes 14 degrees to 38 degrees and does not overlap.
Therefore, by selecting such an emission angle range, P
Light of only polarized light can be obtained, and can act as a polarizing prism.

As described above, according to the first embodiment, the optical axis of the second prism 2 and the optical axis of the first prism 1 are rotated by 90 degrees, and the second axis with respect to the entrance plane B and the exit plane C is rotated. The angle α ₁ and the angle β in the prism 2 are on the same side with respect to the plane F, and the angle β and the angle γ in the third prism with respect to the entrance plane D and the exit plane E are the plane F And the same angle from the boundary. The third prism 3 is provided with a plane having an angle γ with respect to the P-polarized light so that the output angle is equal to the incident angle, so that the angle α ₁ ,
β and γ are set so that the exit angle of the P-polarized light exiting the third prism 3 and the exit angle of the S-polarized light do not overlap, and the allowable angle can be made larger than before. Further, since the incident angle and the output angle can be made equal, the optical axis does not change even if the polarizing prism is rotated. Furthermore, since it is an air gap type, it can withstand high optical power.

In this embodiment, the first prism 1 and the third prism 3 are trapezoidal, but it goes without saying that they may be triangular. Also, the second prism 2
Has a triangular shape, but it goes without saying that a trapezoidal shape may be used. Further, in this embodiment, a Glan-Taylor prism is assumed, but it goes without saying that a Glan-laser type shape may be used so that light reflected by the first prism and the second prism can be used. Further, in the present embodiment, the exit angle of the P-polarized light and the exit angle of the S-polarized light are set so as not to overlap with each other, and the polarizing prism has a high extinction ratio. The output angles of polarized light are at least partially overlapped, and can be used as a low power consumption polarizing prism.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
1 is a diagram showing a basic configuration diagram of a polarization exposure apparatus according to the embodiment. In FIG. 4, those having the same numbers as those in FIG.
This has been described in the first embodiment, and a description thereof will be omitted.
In the polarization exposure device 20, the mercury lamp 4 and the mercury lamp 4
The elliptical mirror 5 having the light-emitting portion as a first focal point and the collimator lens 6 for converting the light condensed by the elliptical mirror 6 into parallel light are applied to the polarizing prism by light within a predetermined incident angle range (this embodiment). In this case, a light source for receiving a quasi-parallel light) is formed. Then, a numerical aperture within an allowable angle range (which is constituted by the first prism 1, the second prism 2 and the third prism 3) within a permissible angle range that acts as a selective light transmitting means that transmits only the outgoing light within a predetermined angle range. (Hereinafter referred to as NA), the integrator 7, the object 8 to be exposed, and the integrator 7
Lens 9 for exposing the object 8 with light from
It is composed of

The operation of the polarization exposure apparatus 20 will be described. The light emitted from the mercury lamp 4 arranged at the first focal point of the elliptical mirror 5 is collected by the elliptical mirror 5 at the second focal point. The collected light is collimated by the collimator lens 6.
The light is made pseudo-parallel. However, since the light emitting portion of the mercury lamp 4 has a finite distance extending between the electrodes, the light condensed on the elliptical mirror 5 does not become a point but has a size having a considerable spread. are doing. For this reason, the light that has passed through the collimator lens 6 and turned into parallel light includes light having an angle with respect to the optical axis. In other words, although light with an angle exceeding the allowable angle of the conventional polarizing prism is included,
In the polarizing prism 10 of the present invention, the allowable angle becomes large, so that a lot of light that cannot be used can be used.

The light emitted from the polarizing prism 10 enters the integrator 7. Here, as described in the first embodiment, in the polarizing prism 10 of the present invention, the P-polarized light has the same incident angle and the outgoing angle, whereas the S-polarized light has a greatly different incident angle and the outgoing angle. Since the integrator 7 has an NA within an allowable angle range for P-polarized light, S-polarized light cannot pass through the integrator 7. Therefore, the light emitted from the integrator 7 is only P-polarized light. This light passes through the condenser lens 9,
The object 8 is exposed.

As described above, according to the second embodiment, the polarizing prism 10 having a large allowable angle (consisting of the first prism 1, the second prism 2 and the third prism 3) and the allowable angle range NA are set. By providing the integral letter 7 having only the P-polarized light, it is possible to increase the allowable angle of the polarizing prism and increase the light use efficiency.
In addition, since it is an air gap type polarizing prism, it can withstand a high power light source. further,
Since the exit angle of the polarizing prism almost coincides with the incident angle,
Even when the polarization direction is rotated, the optical axis and the amount of light on the object to be exposed do not change, and the operability is excellent. In the present embodiment, the light in the allowable angle range is extracted by the integrator 7. However, the configuration may be such that the S-polarized light is not exposed on the object 8 by the combination of the integrator 7 and the condenser lens 9. Needless to say.

[0019]

As described above, according to the present invention,
By rotating the optical axis of the first prism and the optical axis of the second prism by 90 degrees with respect to the optical axis, the angle α ₁ and the angle β in the second prism are on the same side on the plane F, and the third prism Is provided with a surface having an angle γ at which the incident angle of the first prism and the exit angle of the third prism are equal to the P-polarized light.
The allowable angle can be made larger than before while using only polarized light. Further, since the incident angle and the output angle can be made equal, the optical axis does not change even if the polarizing prism is rotated. Furthermore, since it is an air gap type, it can withstand high optical power.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a polarizing prism according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of transmittance characteristics of the polarizing prism according to the embodiment.

FIG. 3 is an explanatory diagram of emission angle characteristics of the polarizing prism in the embodiment.

FIG. 4 is a basic configuration diagram of a polarization exposure apparatus according to a second embodiment of the present invention.

FIG. 5 is a basic configuration diagram of a conventional polarizing prism.

FIG. 6 is an explanatory diagram of transmittance characteristics of a polarizing prism in a conventional mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st prism 2 2nd prism 3 3rd prism 4 Mercury lamp 5 Elliptic mirror 6 Collimator lens 7 Integrator 8 Exposed object 9 Condenser lens 10 Polarizing prism 20 Polarizing exposure apparatus

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H042 CA01 CA09 CA12 2H049 BA05 BA42 BA43 BA47 BB61 BC21 2H099 CA06

Claims (2)

[Claims] 1. A predetermined narrow angle α with respect to a plane F including an optical axis.
₁ and the light exit surface A
A first prism made of a birefringent material having a polarization component direction as an optical axis; a light incident surface B parallel to a light exit surface A of the first prism; and a predetermined angle β with respect to a plane F including the optical axis. A second prism made of a material having the same birefringence as the first prism having an S-polarized component direction as an optical axis with respect to the two surfaces B and C; The prism has a light entrance surface D parallel to the light exit surface C of the prism and a light exit surface E at an angle γ with respect to a plane F including the optical axis. A third prism made of a material having the same birefringence as the first prism described above, wherein the angle α ₁ and the angle β in the second prism are angles on the same side with respect to the plane F. And the angle β and the angle γ in the third prism are defined with respect to the plane F. And the angle γ is set so that the angle of incidence of the P-polarized component light on the first prism along the optical axis and the angle of emergence from the third prism are equal. And a polarizing prism. 2. A polarization exposure apparatus using the polarization prism according to claim 1, wherein: a light source that causes light within a predetermined incident angle range to be incident on the polarization prism; A polarized light exposure apparatus comprising a selective light transmitting means for transmitting only outgoing light within a predetermined angle range.