JPS63271313A - Polarizing device - Google Patents

Abstract

PURPOSE:To enable change of polarization characteristics without losing a quantity of light by spliting a luminous flux to two luminous fluxes having different polarization components, then polarizing one of the luminous fluxes to the luminous flux having the same polarization characteristic as the polarization characteristic of the other luminous flux by a polarizing means and combining again both the luminous fluxes to one luminous flux. CONSTITUTION:The luminous flux which is radiated from a light source 10 and has random polarization characteristics is entered at an arbitrary luminous flux width to a polarized beam splitter 18 by the effect of two lenses; a diffusion lens 12 and a condenser lens 14. The incident luminous flux is then split to P polarized light and S polarized light in the polarized beam splitter 18. One of the split luminous fluxes transmits a halfwave plate 20 and is made into the luminous flux having the same polarization characteristic as the polarization characteristic possessed by another luminous flux. Both the luminous fluxes are then entered to a hexagonal prism 22 by which the fluxes are combined to one luminous flux. This luminous flux is outputted through a lens 24 and a lens 26. The distribution state of the quantity of the resulted luminous flux is, therefore a combination of the two distributions of 1/2 the quantity of light. The change of the polarization characteristics without losing the quantity of light is thereby enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a device for changing the polarization characteristics of light, and more particularly to a device for changing a beam with random polarization characteristics into linearly polarized light.

[Prior Art] In recent years, many optical devices such as mercury lamps and excimer lasers that utilize light beams with random polarization characteristics have been used.

In such devices, it has been necessary to change the polarization characteristics of the randomly polarized beam for various reasons.

Therefore, in the past, the polarization characteristics were changed using a device as shown in FIG.

In the figure, reference numeral 10 denotes a light source that emits a beam with random polarization characteristics, and the light flux emitted from this light source 10 is transmitted through a beam excitation formed by a diffusing lens 12 and a condensing lens 14 whose focal positions are aligned. After passing through the panda and widening the width of the beam, it is configured to enter the polarizing plate 16. ``This polarizing plate 16 allows only light beams having a vibrating surface in one direction to pass through. That is, the light flux having random polarization characteristics that is incident on the polarizing plate 16 becomes linearly polarized light by passing therethrough.

In this way, in the past, the polarization characteristics of incident light were changed by transmitting it through the polarizing plate 16.

[Problems to be solved by the invention] However, in the above-mentioned conventional technology, the polarizing plate 1
The light beam having a plane of vibration (plane of polarization) perpendicular to the light beam passing through the polarizing plate 1 is blocked here.
The amount of light transmitted through the light source 6 is half of the amount of light output from the light source 10.

In other words, there was a problem in that a large amount of light was lost by changing the polarization characteristics.

The present invention has been made in view of this point, and an object of the present invention is to obtain a polarizer whose polarization characteristics can be changed without losing the amount of light.

[Means for Solving the Problems] A polarizer according to the present invention splits a light beam having at least two polarization components into light beams with two different polarization components by a splitting means, and then divides one of the divided light beams into two different light beams. is made into a light beam having the same polarization characteristics as the other light beam by a polarizing means, and then both light beams are combined by a combining means to become one again.
The technical point is to create one luminous flux.

[Operation] In the present invention, a light beam with random polarization characteristics is divided into two light beams whose planes of vibration (polarization planes) are perpendicular to each other by a splitting means, and one of the divided light beams is divided by a polarization means into two light beams that are the same as the other light beam. The beam is converted into a beam with a vibration plane (polarization plane), and the optical axes of both beams are made parallel in the combining means to obtain a single beam again, so the light is not blocked and the amount of light is not lost. This means that the polarization characteristics can be changed.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and numerals 10 to 14 are the same as those of the prior art described above.

In the figure, light emitted from a coherent light source 10 such as a laser is expanded to an appropriate beam width by a diffusing lens 12 and a condensing lens 14 that constitute a beam expander, and then sent to a polarizing beam splitter 18. It is designed to be incident on .

As the polarizing beam splitter 18, there are those using a dielectric material and those using a birefringent crystal.

The light beam incident on the polarizing beam splitter 18 first enters the A plane 18A among the reflecting surfaces, where it is divided into a transmitted light beam (P (m light)) and a reflected light beam (S
(W4 light). Of these, the light beam (S polarized light) reflected by the A surface 18A is incident on the other reflecting surface 18B at a critical angle, where it is 100% reflected and incident on the NIO single wavelength plate 20. It is composed of

The light flux that has entered the NIO one-wavelength plate 20 is given an optical path difference of one NIO wavelength (90° phase difference). That is, the light flux (P-polarized light) has the same polarization characteristics as the light transmitted through the A-plane 18A.

Next, both the luminous flux (P polarized light) that passed through the A surface 18A of the polarizing beam splitter 18 and the luminous flux (P polarized light) that was reflected on the A surface 18A and the 8th surface 18B and then transmitted through the NIO one-wavelength plate 20 are As described above, the light beams enter the hexagonal prism 22 as light beams having the same polarization characteristics.

Both light beams (almost parallel light beams) incident on the hexagonal prism 22 are refracted so that their optical axes are parallel to each other in the vicinity. This hexagonal prism emits two incident light beams at a predetermined interval, and in this embodiment, the incident light beam and the exiting light beam are left and right reversed.

Next, the light that has passed through the hexagonal prism 22 passes through the lenses 24 and 26 as one light beam, and is adjusted to have the same light beam width as that at the time of incidence, and then exits. .

Next, the overall operation of the above embodiment will be explained with reference to FIG. 2.

The light beam with random polarization characteristics emitted from the light source 10 is sent to the polarizing beam splitter 1 with an arbitrary beam width by the action of two lenses, the diffusing lens 12 and the condensing lens 14.
8.

Next, in the polarizing beam splitter 18, the incident light beam is split into P polarized light and S (F4 light).One of the split light beams is transmitted through the partial one-wavelength plate 20, and becomes the same polarized light as the other light beam. It becomes a luminous flux with characteristics.

Next, both light beams enter the hexagonal prism 22, are made into one light beam, are transmitted through the lenses 24 and 26, and are output.

Therefore, the distribution of the amount of light obtained is a combination of two distributions of 1/2 the amount of light as in the prior art. For example, when a beam with a Gaussian distribution is used, the light quantity distribution of the output light beam is as shown in FIG. In FIG. 2, the horizontal axis represents the position in the beam radial direction of the light beam exiting the lens 26, and the vertical axis represents the intensity of the beam.

As described above, in the above embodiment, a light beam having a random polarization characteristic is divided once into two by the polarization beam splitter 18.
After splitting into two linearly polarized light beams (P-polarized light, S-polarized light), the light beam with one of the split polarization characteristics is made to have the same polarization characteristics as the light beam with the other polarization characteristic by the partial single-wavelength plate 20, and then Both light beams are combined by a hexagonal prism 22 and obtained as one light beam again.

Therefore, it is possible to change the polarization characteristics without losing the amount of light.

Note that the present invention is not limited to the above embodiments,
The following various design changes are possible.

For example, when obtaining output light as circularly polarized light, lens 2
It is sufficient to place a quarter wavelength plate after 6 and allow the light to pass through.

In addition, in order to route the beam while minimizing the loss of light quantity, the light beam may be changed to S-polarized light and may be configured to be incident on the polarization beam splitter at the Brewster angle and the critical angle.

Furthermore, since there is no light loss, it is also effective to use it in devices that control the light amount by rotating the polarizing plate.If the beam light amount distribution is flattened using a fly-eye lens, etc., it can be used as an excimer laser with a Gaussian distribution. It can also be fully used in exposure apparatuses using, etc.

[Effects of the Invention] As described above, according to the present invention, there is an effect that polarization characteristics can be changed without loss of light quantity.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a graph showing the operation of the embodiment, and FIG. 3 is a block diagram showing an example of the prior art. "Explanation of symbols of main parts" 10...Light source, 18...Polarizing beam splitter, 2
0... part of the single wavelength plate, 22... hexagonal prism. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] A polarizer that changes the polarization characteristics of a light beam having at least two polarization components emitted from a light source, comprising: a polarizer that divides the light beam emitted from the light source into two different polarization components by changing the optical path; a splitting means; a polarizing means disposed in one optical path of the split light beam to make the polarization state of the light flux passing through the optical path the same as the polarization state of the other light flux; A polarizer comprising a combining means for combining light beams into one light beam.