JP2011064890A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device outputting light having arbitrary spectral distribution characteristics. <P>SOLUTION: Light emitted from a white light source 101 enters an input slit 1, and collimated to enter a polarization beam splitter 103. Only linearly polarized light in a direction roughly parallel to a paper surface and orthogonal to an optical axis pass through the beam splitter 103 and is condensed in the opening of a stray light cut slit 2. Light emitted from the opening enters a grating 106 having a wavelength dispersion operation to form a spectrum image. A reflective liquid crystal array device 108 placed in a position where the spectrum image is formed is a modulation element to be independently controlled, and light emitted therefrom becomes an elliptically polarized light different for each wavelength element. In this optical system, the size of the opening of the stray cut slit is set larger than the opening image of an input slit formed by a polarized light branch optical system and the opening image of an input slit formed by a wavelength dispersion type spectral optical system. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light source device.

  The following light source devices are known. In this light source device, the light reduction amount of each wavelength component is calculated in order to realize the designated spectral distribution. Then, the tilt angle of the micromirror is calculated based on the calculated light reduction amount, and the micromirror is controlled based on the calculated tilt angle, thereby irradiating light with a desired spectral distribution (for example, Patent Document 1).

JP 2006-184234 A

  However, when the incident light and the reflected light from the micromirror are passed through one input / output slit as in the conventional light source device, the reflected light from the micromirror is imaged on the input / output slit. Due to the aberration of the optical system, the image formed on the input / output slit is blurred, the input / output slit cannot pass all of the reflected light, and the transmittance of the light source device may deteriorate.

The light source device according to the present invention is arranged between the input slit for limiting the incident light beam from the light source, the stray light cut slit, and the input slit and the stray light cut slit, and receives the incident light beam from the light source restricted by the input slit. A splitting optical system that branches into a plurality of light beams and outputs the one light beam to the stray light cut slit, and is disposed between the input slit and the stray light cut slit. A first imaging optical system that forms an image) in the vicinity of the stray light cut slit, a spectroscopic optical system that splits the light beam input through the stray light cut slit into each wavelength component, The modulation means that modulates the reflected light flux of each wavelength component and reflects it toward the spectroscopic optical system, and is disposed between the stray light cut slit and the modulation means, and is reflected by the modulation means. A second imaging optical system that re-forms an aperture image of the input slit (hereinafter referred to as a “second aperture image”) in the vicinity of the stray light cut slit, and the spectroscopic optical system is reflected by the modulation means The light beam of each wavelength component is synthesized, and the branching optical system branches the light beam output from the stray light cut list into a plurality of light beams and outputs one light beam as output light. The size of the opening of the stray light cut slit is The first aperture image and the second aperture image are determined to be larger than the first aperture image and the second aperture image.
In the present invention, the first imaging optical system includes a lens for collimating the incident light beam from the input slit into parallel light, and an image for forming the light beam branched by the branching optical system in the vicinity of the stray light cut slit. It is preferable to be comprised with a lens.
The second imaging optical system includes a lens for collimating the reflected light beam from the modulation means into parallel light, and a lens for forming an image of the light beam synthesized by the spectroscopic optical system in the vicinity of the stray light cut slit. It is preferred that
The size of the opening of the stray light cut slit is determined in consideration of at least one of the magnification of the first imaging optical system, the aberration of the first imaging optical system, and the aberration of the second imaging optical system. You may do it.
The size of the opening of the input slit may be variable.
The size of the stray light cut slit opening may be set larger than the maximum size of the input slit opening.
When the size of the opening of the input slit is changed, a changing means for changing the size of the opening of the stray light cut slit according to the size of the changed opening may be further provided.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that the transmittance | permeability of a light source device deteriorates.

It is a block diagram which shows the structure of one Embodiment of a light source device. It is a figure which shows the specific example in case a part of opening image of an input slit is made by the stray light cut slit 2. FIG. It is a figure which shows the relationship between the opening image of the input slit 1, and the opening of the stray light cut slit 2. FIG.

  FIG. 1 is a block diagram showing a configuration of an embodiment of a light source device in the present embodiment. The light source device 100 includes a white light source 101, an input slit 1, a relay lens 102, a polarization beam splitter 103, a relay lens 104, a stray light cut slit 2, a collimator lens 105, a grating 106, and an imaging lens 107. A reflective liquid crystal element array device (spatial modulation element) 108, a spatial modulation element driver 109, a condenser lens 110, and an output slit 3.

  As the white light source 101, for example, a xenon lamp or a halogen lamp is used. The input slit 1 is disposed at the front focal position of the relay lens 102, and the resolution of the light source device 100 is determined by the size of the opening of the input slit 1. Note that the size of the opening of the input slit 1 may be fixed or variable. The light emitted from the white light source 101 is incident on the input slit 1 disposed at the front focal position of the relay lens 102, collimated into substantially parallel light by the relay lens 102, and input to the polarization beam splitter 103.

  As for the light incident on the polarization beam splitter 103, only linearly polarized light whose electric field vector is substantially parallel to the plane of the paper of FIG. 1 and perpendicular to the optical axis passes through the polarization beam splitter 103, and is stray light cut slit by the relay lens 104. 2 is condensed into the opening. Here, the relay lens 102, the polarization beam splitter 103, and the relay lens 104 constitute a polarization branching optical system. That is, an aperture image of the input slit 1 is formed in the vicinity of the stray light cut slit 2 by the polarization branching optical system. The stray light cut slit 2 is formed with a substantially rectangular opening in a direction substantially perpendicular to the paper surface of FIG.

  The light emitted from the opening of the stray light cut slit 2 is collimated into substantially parallel light by the collimator lens 105, enters the grating 106 having a wavelength dispersion action, and forms a spectrum image by the imaging lens 107. The collimator lens 105, the grating 106, and the imaging lens 107 constitute a wavelength dispersion type spectroscopic optical system. A reflective liquid crystal element array device 108 that is a spatial modulation element is disposed at a position where a spectrum image can be formed.

  The reflective liquid crystal element array device 108 includes a liquid crystal layer 108b, a cover glass 108a having a wedge shape on the incident side across the liquid crystal layer 108b, and a flat mirror 108c at a position facing the cover glass 108a with respect to the liquid crystal layer 108b. Is arranged. The liquid crystal layer 108b is sealed between the cover glass 108a and the flat mirror 108c. The reflected light intensity other than the surface reflection on the surface in contact with the outside of the cover glass 108a can be ignored in practice. The cover glass 108a can be used as long as it is made of a transparent medium other than glass.

  Although not shown in FIG. 1, the reflective liquid crystal element array device 108 includes a plurality of liquid crystal elements that are modulation elements that are independently controlled, one-dimensionally arranged, and the direction of the arrangement is the wavelength dispersion direction of the spectrum image. Which coincides with the direction perpendicular to the paper surface of FIG. The individual liquid crystal elements arranged one-dimensionally in the reflective liquid crystal element array device 108 are independently controlled by the spatial modulation element driver 109, and the light traveling back and forth in the individual liquid crystal elements is given different retardation for each element. The

  The light emitted from the reflective liquid crystal element array device 108 becomes elliptically polarized light that differs for each element, that is, for each wavelength element. The light that has been elliptically polarized by the reflective liquid crystal element array device 108 has a wavelength multiplexing action in the course of traveling through the wavelength dispersion type spectroscopic optical system including the imaging lens 107, the grating 106, and the collimator lens 105. The light is collected at the opening of the stray light cut slit 2. That is, an aperture image of the input slit 1 reflected by the reflective liquid crystal element array device 108 is formed in the vicinity of the stray light cut slit 2 by the wavelength dispersion type spectroscopic optical system.

  The light emitted from the opening of the stray light cut slit 2 is collimated by the relay lens 104 and enters the polarization beam splitter 103. The polarization separation unit of the polarization beam splitter 103 reflects linearly polarized light in a direction orthogonal to the electric field vector of incident light, and is collected by the condenser lens 110 at the opening of the output slit 3 disposed at the rear focal position. . Thereby, the light emitted from the output slit 3 can be irradiated to the outside.

  In the light source device 100 according to the present embodiment, the size of the opening of the stray light cut slit 2 needs to be a size that can cut the generated stray light and the size of the opening image of the input slit 1 can pass through. is there. Specifically, first, the size of the opening of the stray light cut slit 2 needs to be set larger than the opening image of the input slit 1 formed in the vicinity of the stray light cut slit 2 by the polarization branching optical system. Thereby, the aperture image of the input slit 1 formed by the polarization splitting optical system can pass through without being lost by the stray light cut slit 2.

  Secondly, the size of the opening of the stray light cut slit 2 is the opening of the input slit 1 reflected by the reflective liquid crystal element array device 108 formed in the vicinity of the stray light cut slit 2 by the wavelength dispersion type spectroscopic optical system. It must be set larger than the image. Thereby, the aperture image of the input slit 1 formed by the wavelength dispersion type spectroscopic optical system can pass through without being lost by the stray light cut slit 2.

  For example, the aperture image of the input slit 1 formed by the wavelength dispersion type spectroscopic optical system may be blurred due to the aberration of the wavelength dispersion type spectroscopic optical system. In this case, when the size of the opening of the stray light cut slit 2 is the same as the size of the input slit 1, the opening of the input slit 1 formed by the wavelength dispersion type spectroscopic optical system as shown in FIG. There is a possibility that the size of the image (input slit image) 2a is larger than the size of the opening 2b of the stray light cut slit 2, and the stray light cut slit 2 may scatter the signal light.

  In order to avoid this, in the present embodiment, as shown in FIG. 3, the size of the opening 2b of the stray light cut slit 2 is larger than the size of the image blurred by the aberration of the wavelength dispersion type spectroscopic optical system. In addition, the size of the opening 2b of the stray light cut slit 2 is set. That is, the size of the opening 2b of the stray light cut slit 2 is set larger than the size of the opening of the input slit 1 in consideration of the aberration of the wavelength dispersion type spectroscopic optical system.

  Further, since the magnification of the wavelength dispersion type spectroscopic optical system is generally equal, it is not necessary to consider the magnification of the wavelength dispersion type spectroscopic optical system when determining the size of the opening 2b of the stray light cut slit 2. On the other hand, since the magnification of the polarization branching optical system is not necessarily equal, when the magnification of the polarization branching optical system is not equal, the size of the opening 2b of the stray light cut slit 2 is determined. Needs to take into account the magnification of the polarization splitting optical system. Similarly to the case of the wavelength dispersion type spectroscopic optical system, the aperture image 2a of the input slit 1 is blurred due to the aberration of the polarization splitting optical system. Therefore, when determining the size of the aperture 2b of the stray light cut slit 2, It is necessary to consider the aberration of the branching optical system.

  For example, as described above, the input slit formed in the vicinity of the stray light cut slit 2 by the polarization branching optical system is larger than the size of the opening 2b of the stray light cut slit 2 set in consideration of the aberration of the wavelength dispersion type spectroscopic optical system. When the size of the aperture image 2a of 1 is large, the stray light cut slit 2 is added so that the stray light cut slit 2 does not block the aperture image 2a of the input slit 1 in consideration of the magnification and aberration of the polarization splitting optical system. It is necessary to set the size of the opening 2b.

  When the size of the aperture of the input slit 1 is variable, the aperture size 2b of the stray light cut slit 2 is set to the maximum size of the aperture of the input slit 1 as a target. If the size is set in consideration of the aberration, the magnification of the polarization splitting optical system and the aberration, the stray light cut slit 2 is always the aperture image of the input slit 1 even if the aperture size of the input slit 1 is changed. 2a can be prevented. Alternatively, when the size of the opening of the input slit 1 is changed, the stray light cut slit is set so that the stray light cut slit 2 does not capture the opening image 2a of the input slit 1 according to the changed size of the opening. You may make it change the magnitude | size of 2 opening.

According to the present embodiment described above, the following operational effects can be obtained.
(1) The size of the opening 2b of the stray light cut slit 2 is set larger than the opening image of the input slit 1 formed by the polarization splitting optical system and the opening image of the input slit 1 formed by the wavelength dispersion type spectroscopic optical system. I did it. Thereby, it is possible to prevent the opening image of the input slit 1 from being blurred by the stray light cut slit 2 and to prevent the transmittance of the light source device 100 from deteriorating.

(2) The size of the opening of the stray light cut slit 2 is determined in consideration of the magnification of the polarization branching optical system, the aberration of the polarization branching optical system, and the aberration of the wavelength dispersion type spectroscopic optical system. As a result, the aperture image 2a of the input slit 1 is enlarged due to the magnification of the polarization splitting optical system, the aperture image 2a of the input slit 1 is blurred due to the aberration of the polarization splitting optical system, or input due to the aberration of the wavelength dispersion type spectroscopic optical system. Even if the aperture image 2 a of the slit 1 is blurred, the stray light cut slit 2 can be prevented from losing the aperture image 2 a of the input slit 1.

(3) Since the size of the opening of the input slit 1 may be variable, the resolution of the light source device 100 can be arbitrarily changed by changing the size of the opening of the input slit 1.

(4) When the size of the opening of the input slit 1 is variable, the size of the opening 2b of the stray light cut slit 2 is fixed to the size of the maximum size of the opening of the input slit 1. I tried to keep it. Thereby, even if the size of the opening of the input slit 1 is changed, the stray light cut slit 2 can be prevented from losing the opening image 2 a of the input slit 1.

(5) When the opening size of the input slit 1 is changed, the size of the opening 2b of the stray light cut slit 2 is changed according to the changed opening size. Thereby, even if the size of the opening of the input slit 1 is changed, the stray light cut slit 2 can be prevented from losing the opening image 2 a of the input slit 1.

-Modification-
The light source device of the above-described embodiment can be modified as follows.
(1) The example in which the light source device 100 in the above-described embodiment includes the white light source 101 has been described. However, instead of the white light source 101, an optical fiber for introducing light from an external light source may be provided, and incident light from the external light source may be taken in via the optical fiber.

(2) In the light source device 100 in the above-described embodiment, the example in which the light emitted from the output slit 3 is directly irradiated to the outside has been described. However, an optical fiber for deriving the light emitted from the output slit 3 to the outside may be provided, and the light emitted from the output slit 3 may be derived to the outside via the optical fiber.

(3) In the embodiment described above, the reflected light from the reflective liquid crystal element array device 108 synthesized by the wavelength dispersion type spectroscopic optical system passes through the stray light cut slit 2 and the output slit 3 and is irradiated to the outside. An example was described. However, in FIG. 1, the output slit 3 is eliminated, the arrangement position of the stray light cut slit 2 is changed to the position where the output slit 3 is arranged, and the reflected light from the reflective liquid crystal element array device 108 is stray light cut slit 2. It is also possible to irradiate outside through only the light.

(4) In the above-described embodiment, the example in which the light source device 100 changes the light of each wavelength component by the reflective liquid crystal element array device 108 has been described. However, as in the light source device described in Japanese Patent Application Laid-Open No. 2006-184234, the light of each wavelength component may be attenuated using a micromirror.

  Note that the present invention is not limited to the configurations in the above-described embodiments as long as the characteristic functions of the present invention are not impaired. Moreover, it is good also as a structure which combined the above-mentioned embodiment and a some modification.

100 light source device, 1 input slit, 2 stray light cut slit, 3 output slit, 101 white light source, 102, 104 relay lens, 103 polarization beam splitter, 105 collimator lens, 106 grating, 107 imaging lens, 108 reflective liquid crystal element array Device (spatial modulation element), 109 Spatial modulation element driver, 110 Condenser lens

Claims (7)

An input slit that limits the incident light flux from the light source;
Stray light cut slit,
Branch optics that is arranged between the input slit and the stray light cut slit and branches an incident light beam from a light source limited by the input slit into a plurality of light beams and outputs the one light beam to the stray light cut slit The system,
A first image formed between the input slit and the stray light cut slit and forming an aperture image of the input slit (hereinafter referred to as a “first aperture image”) in the vicinity of the stray light cut slit. Optical system,
A spectroscopic optical system that splits the light beam input through the stray light cut slit into each wavelength component;
Modulating means for modulating the light flux of each wavelength component dispersed by the spectroscopic optical system and reflecting it toward the spectroscopic optical system;
An aperture image of the input slit (hereinafter referred to as a “second aperture image”) disposed between the stray light cut slit and the modulation means and reflected by the modulation means is in the vicinity of the stray light cut slit. A second imaging optical system for reshaping,
The spectroscopic optical system combines the light fluxes of the respective wavelength components reflected by the modulation means,
The branching optical system branches the light beam output from the stray light cut list into a plurality of light beams and outputs the one light beam as output light,
The size of the opening of the stray light cut slit is determined to be larger than the first opening image and the second opening image. The light source device according to claim 1,
The first imaging optical system includes a lens for collimating an incident light beam from the input slit into parallel light, and an image for forming the light beam branched by the branching optical system in the vicinity of the stray light cut slit. A light source device comprising a lens. The light source device according to claim 1 or 2,
The second imaging optical system is configured to form an image in the vicinity of the stray light cut slit by a lens for collimating the reflected light beam from the modulation means into parallel light and the light beam synthesized by the spectroscopic optical system. A light source device comprising a lens. In the light source device according to any one of claims 1 to 3,
The size of the opening of the stray light cut slit takes into account at least one of the magnification of the first imaging optical system, the aberration of the first imaging optical system, and the aberration of the second imaging optical system. A light source device characterized by being defined as follows. In the light source device according to any one of claims 1 to 4,
The light source device characterized in that the size of the opening of the input slit is variable. The light source device according to claim 5,
The size of the opening of the stray light cut slit is determined to be larger than the maximum size of the opening of the input slit. The light source device according to claim 6,
The light source device further comprising a changing unit that changes the size of the opening of the stray light cut slit according to the size of the changed opening when the size of the opening of the input slit is changed. .

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