KR101376290B1 - Polychromator comprising multi reflection filter - Google Patents

Abstract

The present invention relates to a spectroscopic diagnostic apparatus and a thomson scattering diagnostic polychromator. More specifically, the present invention relates to a polychromator which detects light after spectroscopically incident light in a cascade manner using a first reflective interference filter and then causing multiple reflections using a second reflective interference filter.

Description

POLYCHROMATOR COMPRISING MULTI REFLECTION FILTER}

The present invention relates to a spectroscopic diagnostic apparatus and a thomson scattering diagnostic polychromator. More specifically, the present invention relates to a polychromator which detects light after spectroscopically incident light in a cascade manner using a first reflective interference filter and then causing multiple reflections using a second reflective interference filter.

Plasma means that when a substance is heated up to several hundred million degrees, electrons are separated one by one from the gas of the molecular state and separated into negatively charged electrons and positively charged ions. It is a self-restraint fusion method applied to the tokamak by applying a strong magnetic field around the charged particles to float the plasma in the air and heating the plasma, considering that the plasma is composed of charged particles.

Korean tokamak device is a KSTAR (KOREA SUPERCONDUCTING TOKAMAK ADVANCED RESEARCH) device. As with any Tokamak device, plasma diagnostics are important for KSTAR devices.

To this end, there are a variety of plasma diagnostic apparatus, there may be a device that is disposed in KSTAR, such as a spectroscopic diagnostic apparatus and a Thomson scattering diagnostic apparatus for diagnosing the plasma by an optical measurement method.

The spectroscopic diagnostic apparatus is preferably polychromator, rather than monochromator, for plasma diagnosis in the Tokamak apparatus, which must be measured quickly and in a short time according to the change of time, and the efficiency of data measurement in the entire wavelength range should be improved.

This diagnostic device also requires flexibility in the size of the device and the arrangement of the device, especially in the case of high magnetic field high energy devices such as Tokamak.

There are various types of polychromators in the prior art. A widely used type is the Paschen Runge type polychromator (JP 58-190731). It consists of an inlet slit, a concave grating and an outlet slit. That is, in general, diffraction gratings are used for scattering of the spectrum of incident light and for isolation of the scattered light. Diagnostic devices using such diffraction grafts have the disadvantages of stray light rejection, independent channel response, and inaccurate light measurement in noisy environments. There are also many spatial and size limitations in the installation of diagnostic devices for spectroscopic light.

Accordingly, a spectroscopic apparatus for spectroscopy of incident light in multiple stages using an interference filter as disclosed in Korean Patent Publication No. 10-2005-0111579 has been considered. This device has the advantage of not using a diffraction grating, but there is a problem in the position of the photodetector detecting the wavelength of a specific band transmitted through the transmission interference filter and the structural limitation of the spectrometer by using a transmission interference filter.

Moreover, diagnostic devices for the use of tokamak devices require high performance diagnostic devices due to the inherent properties of the above mentioned tokamak, and require flexibility in placement and size of the devices.

In addition, in the conventional polychromator, it is difficult to accurately detect a specific wavelength band transmitted through the filter due to mutual interference between channels because the wavelength characteristics of the selected wavelength invade neighboring filter wavelength bands. In order to solve this problem, a high performance filter using an increase in the number of layers of the filter has been used. However, such a high performance filter has a problem that its manufacturing cost is very expensive.

In order to solve the problems of the prior art and to satisfy the requirements, the present inventors use a configuration of a collimating lens, a reflective interference filter, and the like, through the separation of the cascade method of incident light. A collimator Thomson scattering spectrometer was designed.

In addition, in the case of a polychromator, when a plurality of transmissive interference filters are used, accurate results may be obtained only when the wavelength characteristics of the filter according to the wavelength do not infringe the wavelength bands of neighboring filters. That is, accurate wavelength selectivity can be increased by minimizing the interference between channels. In order to minimize such inter-channel coherence, the present inventors use a reflective interference filter to extract light of a selected wavelength, and then arrange the reflective filters facing each other to generate multiple reflections to remove noise and to reduce signal coherence between channels. After minimizing, we designed a polychromator that includes multiple reflection filters to detect with photodetector.

1 is a cross-sectional view of a polychromator using the reflective interference filter of the present invention in accordance with an embodiment of the present invention.
2 is a cross-sectional view of a polychromator using the reflective interference filter and opposing reflective filter arrangement of the present invention, in accordance with an embodiment of the present invention.
3 is a graph of wavelength bands transmitted through a filter as a result of detection by a polychromator using the reflective interference filter and opposing reflective filter arrangement of the present invention.
Various embodiments are now described with reference to the drawings, wherein like reference numerals are used throughout the drawings to refer to like elements. For purposes of explanation, various descriptions are set forth herein to provide an understanding of the present invention. It is evident, however, that such embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the embodiments.

The following description provides a simplified description of one or more embodiments in order to provide a basic understanding of embodiments of the invention. This section is not a comprehensive overview of all possible embodiments and is not intended to identify key elements or to cover the scope of all embodiments of all elements. Its sole purpose is to present the concept of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later.

1 is a cross-sectional view of a polychromator using the reflective interference filter of the present invention, in accordance with an embodiment of the present invention, and FIG. 2 is a reflective interference filter of the present invention and opposing, in accordance with an embodiment of the present invention. A cross-sectional view of a polychromator using a reflective filter arrangement. 1 is a state in which a pair of reflective interference filters are not disposed, and FIG. 2 is a state in which pairs of reflective interference filters facing each other are arranged. Hereinafter will be described with reference to FIG.

As shown in FIG. 2, a polychromator including a multiple reflection filter according to an embodiment of the present invention includes a collimation lens unit 110; A plurality of first reflective interference filters 120a, 120b, 120c, 120d and 120e having different transmission and reflection wavelength bands, a plurality of pairs of second reflective interference filters 150a, 150b, 150c, 150d. 150e and a plurality of Light detectors 130a, 130b, 130c, and 130d.

The collimation lens unit 110 collects the light from the light source or makes the parallel light. For example, a collimation lens portion consisting of a combination of a convex lens and a concave lens or a slit may be considered, and it is obvious to those skilled in the art that the present invention is not limited to this manner.

The plurality of first reflective interference filters 120a, 120b, 120c, 120d, and 120e may have planes of the reflective interference filter along a path of parallel light 140 emitted from the collimation lens unit 110. It is arranged in a line not perpendicular to the path of light. Preferably, the acute angle of the angle formed by the traveling path axis of the incident light and the interference filter plane is 45 degrees.

The first reflective interference filter is a filter that reflects only light of a specific wavelength band and passes light of the remaining wavelength band. That is, the first reflective interference filter reflects only light of a wavelength band desired to be detected and other wavelengths are transmitted.

These first reflective filters are sequentially arranged in a line according to the advancing direction of the incident light. According to this arrangement, it is possible to implement a miniaturized polychromator by minimizing the optical path, it is possible to provide a polychromator of a simple structure that can minimize the loss during the optical signal processing by matching the optical axis and easily manufactured.

A pair of second reflective interference filters is disposed on the reflection path of the light of the first plurality of reflective interference filters. In this case, the transmission and reflection bands of the second reflection interference filter are the same as the transmission and reflection bands of the corresponding first reflection interference filter. That is, in FIG. 2, the transmission and reflection bands of the first reflection interference filter 120a and the transmission and reflection bands of the second reflection interference filter 150a are the same.

The second reflective interference filters 150a, 150b, 150c, 150d and 150e are arranged in pairs to face each other, because light of the wavelength selected by the first reflective interference filter is incident on the pair of opposite reflective filters. To cause multiple reflections within the pair of second reflective interference filters. Arranging such pairs of second reflective interference filters to face each other is also referred to as filter slap. In this case, however, the reflective surfaces of the pair of the second reflective interference filter should be arranged not parallel to the traveling path of the light reflected by the first reflective interference filter. This is because multiple reflections do not occur inside the pair of second reflective interference filters if the reflective surfaces of the pair of second reflective interference filters are parallel to the traveling path of the light reflected by the first reflective interference filter.

Through the pair of the second reflective interference filter to multi-reflect the light of the wavelength band reflected by the first reflective interference filter therein, thereby removing noise and minimizing the inter-channel signal coherence will be described later As described above, light can be detected by the light detector.

The arrangement of the second reflective interference filter to enable such multiple reflections can replace a high performance filter that requires a large number of layers mentioned in the prior art, and also has excellent wavelength characteristics results. Figure 3 shows the results detected by the polychromator including a multiple reflection filter in accordance with an embodiment of the present invention.

As shown in Figure 3, it can be seen that the shape of the graph of the wavelength band transmitted through the filter is almost rectangular, thereby minimizing the invasion of the mutual area between the filters of wavelength bands adjacent to each other. If there is no filter slab configuration that causes multiple reflections as in the present invention, the wavelength region may fall apart while forming a smooth curve rather than falling sharply as shown in FIG.

That is, the present invention implements a polychromator that minimizes interference between channels without using a high-performance filter by configuring a filter slab in which a pair of second reflective interference filters are disposed to face each other.

In this case, the pair of the second reflective interference filter is placed so that a plurality of reflections occur within a short distance by placing the reflective surfaces of the pair of the second reflective interference filter almost perpendicular to the axis of the light reflected from the first reflective interference filter. Can be arranged, thereby making the overall size of the polychromator small. In this arrangement, even if the size of the second reflective interference filter is small, the effect of multiple reflections can be sufficiently obtained.

On the other hand, the light detector 130a, 130b, which detects the light of the specific wavelength reflected on the path of the light of the particular wavelength reflected from the first reflective filter and multiple reflections in the pair of the second reflective interference filter, 130c, 130d, 130e are disposed.

The light detector may include a photodiode and may include a focusing lens.

The polychromator of the present invention multiplies the light in a cascade with the first reflective interference filter and multi-reflects the light of a specific wavelength reflected by the first reflective interference filter using the second reflective interference filter. The light can then be detected. The photo detector may be arranged in various structures around the light path, and the various structures may be arbitrarily selected according to the environment, thereby increasing the suitability of the use environment, and branching only the light to be detected to the surrounding detector. Branched, most of the remaining light does not change the traveling path, in particular in the environment to be diagnosed remotely in the detection of electromagnetic waves emitted from a high-energy source such as tokamak there is no limitation of the light traveling path or the light traveling path It can be very beneficial for the device to keep it constant.

A series of methods for spectroscopic and light detection of the polychromator of the present invention will be described below. Condensed or parallel light formed from the collimation lens unit is transmitted to the first interference filter 120a in the polychromator of the present invention. Specific wavelength bands λ1 to λ2 included in the first interference filter 120a are reflected and light in other wavelength ranges is transmitted. The transmitted light is transmitted to the first interference filter 120b located next. Specific wavelength bands λ2 to λ3 of the first interference filter 120b are reflected and light in other wavelength regions is transmitted. The transmitted light is likewise transmitted to the next first interference filter 120c. Specific wavelength bands λ3 to λ4 included in the first interference filter 120c are reflected and light in other wavelength ranges is transmitted. In this way, the remaining interference filters are cascaded.

As such, the light of a specific wavelength band reflected by the first interference filter 120a, 120b, 120c, ... is multi-reflected by the pair of second reflective interference filter 150a, 150b, 150c, .... The light of the (λ1 to λ2) wavelength band reflected by the first interference filter 120a causes multiple reflection to occur in the pair 150a of the second reflective interference filter that reflects the light of the (λ1 to λ2) wavelength band. The same process occurs in a pair of second reflective interference filters such as 150b and 150c.

In this way, the multi-stage classified light in the first reflective interference filter and the multi-reflected light in the second reflective interference filter are finally detected by the photo detector, and the wavelength characteristics of the detected light are shown in FIG. You can see the sharp drop in the place where the wavelength falls.

The description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features presented herein.

Claims (2)

Collimation lens unit;
A plurality of first reflective interference filters having different transmission and reflection wavelength bands;
A pair of second reflective interference filters having the same transmission and reflection bands as each of the plurality of first reflective interference filters are disposed so as to face each other on a reflection path of light of the corresponding first reflective interference filter; A plurality of second reflective interference filter pairs for multiple reflection of light reflected by the first reflective interference filter; And
Including a plurality of light detectors,
The plurality of first reflective interference filters are sequentially arranged in a line along the path of the light emitted from the collimation lens unit, and each plane of the first reflective interference filter has a 45 degree angle with the traveling path axis of the light. At an acute angle,
Reflecting surfaces of the pair of the second reflective interference filter are disposed not parallel to the traveling path of the light reflected by the first reflective interference filter,
A light detector which detects light of the specific wavelength is disposed on a path of the light of the specific wavelength reflected from the first reflective interference filter and multiple reflected by the pair of the second reflective interference filter,
The reflective surfaces of the pair of second reflective interference filters are disposed perpendicular to the axis of the propagation path of light reflected from the first reflective interference filter,
Ultra-compact polychromator with multiple reflection filters. delete

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