JP2607185Y2 - Spectrometer - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in wavelength spectrum resolution in a spectrometer for measuring a wavelength spectrum of light by a diffraction grating.

[0002]

2. Description of the Related Art Each component will be described with reference to an example of a configuration diagram of a conventional spectroscopic device shown in FIG. 3 and FIGS. 2A and 2B.

[0003] The overall operation principle will be described. Light input from outside via an optical fiber cable is
Light enters from 1. Next, the incident light beam is converted into a parallel light beam by the parabolic mirror 12 and is incident on the next diffraction grating 14. Here, the incident parallel light beam has the same Gaussian characteristic curve in both the X direction and the Y direction, like the beam shape incident on the diffraction grating in FIG. The parallel rays are split by the diffraction grating 14 and output to the parabolic mirror 16.

[0004] In the split light beam, only a specific wavelength component is diffracted and condensed by the parabolic mirror 16 and output to the photodetector 18. Here, a slit 17 is provided at the focal position in front of the photodetector, and passes only the wavelength of the slit width here. Then, the light is converted into an electric signal corresponding to the light intensity by the photodetector 18 provided behind the slit and is used for measurement.

[0005] In the above description, an aperture 13 is provided on the light receiving surface of the diffraction grating in order to improve the spectral resolution. The shape of the opening device is a sawtooth-shaped shielding slit, and has a jagged shape in which the side in the Y-axis direction is sawtoothed. After passing through the opening device, the light slit 1
The spot shape of the light beam projected on 7 is converted as shown in FIG.

Here, the spot shape shown in FIG. 2B is such that the slit 1 after a single wavelength is incident and passes through the aperture unit.
7 shows an example of a spot shape on the spot 7. This shape conversion is an effect of the aperture device described above. As a result, it can be seen that the spread of the spot in the X-axis direction is significantly reduced as compared with FIG. Since this is a spot shape in which the spot spread in the X direction is suppressed, the spectral resolution is improved.

The diffraction grating is provided on a rotation mechanism 15 for rotating the diffraction grating. The rotation mechanism has a structure in which the rotation mechanism arbitrarily rotates around the center Y axis of the diffraction grating. When a spectrum in a target wavelength range is to be measured, the rotation mechanism is controlled to rotate a range of a predetermined rotation angle according to the measurement wavelength range. As a result, the target separated light component is condensed on the photodetector 18 and read and measured.
That is, measurement of an arbitrary wavelength spectrum is realized by the rotation mechanism 15.

[0008] The spectral resolution of the slit 17
This is achieved by changing the slit width. For this reason, a mechanism is provided that makes one piece of the slit movable, and a mechanism that can set and control the slit interval with high accuracy by a stepping motor is provided. The spectral resolution thereby has a variable width range of, for example, 0.1 nm to 5.0 nm. Usually, when measuring light with a wide spectrum width such as an LED, the measurement is performed with a wide slit, and conversely, with a laser diode, the measurement is performed with a narrow slit. In addition, the thickness of the tip portions of both slits is reduced to, for example, about 20 μm in order not to hinder the passage of light.

An object of the present invention is to further improve the spectral resolution of light without largely changing the structure of a current spectroscopic device.

[0010]

In order to solve the above-mentioned problem, in the configuration of the spectroscopic device of the present invention, a rotating diffraction grating is provided.
More, the direction of wavelength sweep of the incident light is referred to as an X-axis direction, in a spectroscopic apparatus for measuring an optical spectrum, the X-axis direction bi
Windows in the optical path to convert the beam spot shape
The direction orthogonal to the X-axis direction to be swept is defined as the Y-axis direction, and the shielding shape of the window in the Y-axis direction is a sawtooth shape that is not parallel to the Y-axis.
In addition , an aperture 13 having a transmittance of 1 inside the window and a transmittance of 0 outside the window is provided. In the slit for setting the resolution of the optical spectrum, the aperture is provided in the form of a beam spot.
The spectroscopic device is realized by providing a vertical slit 19 that blocks a beam spot diffracted in the side direction of the slit 17 that appears when the shape is changed. That is, a vertical slit 19 is provided at a conventional slit position as a second slit for blocking light rays in the Y-axis direction. In addition, an aperture unit 13 is provided for converting the beam spot shape by providing a sawtooth-shaped shield on the side in the Y-axis direction. Then, in the spot shape of the light beam converted by the aperture unit 13, a structural means for shielding the light beam in the area of the spots 32 and 33 in FIG.

In the arrangement structure of the vertical slits, the slit width is set to, for example, about 0.1 to 0.5 mm so that the beam spot portion to be shielded and removed can be effectively formed. In addition, the arrangement position of the vertical slit has an arrangement structure adjacent to (or behind) the conventional slit 17.

Further, the vertical slit has an arrangement structure in which it is installed at a position slightly deviated from the position of the focal length. This is because the conventional slit 17 must be arranged at the focal position. However, since the width of the vertical slit is sufficiently larger than that of the spot shape, the effect of lowering the light shielding performance is small.

[0013]

The vertical slit 19 is a spot component (FIG. 2 (b)) discrete on the Y-axis by the aperture unit 13, and has a function of deleting the spot areas (32, 33) which have conventionally caused performance degradation. Have. This has the role of further improving the spectral resolution. That is, FIG.
The slit range on the Y axis is limited to 36 by the vertical slit 19 as shown in FIG. As a result, 3 in FIG.
There is a function of blocking the regions 2 and 33 and passing only the region 31.

The aperture unit 13 changes the beam shape of the incident Gaussian characteristic curve (FIG. 2A) into a spot shape (FIG. 2) that effectively limits the spread of the beam spot in the X-axis direction.
(B)). That is, it has the effect of suppressing the beam component on the X axis and moving it in the vertical Y axis direction.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention are shown in FIG. 1 as an example of the configuration of the spectroscopic device of the present invention, a conventional slit-shaped light passage range in FIG. 2C, and a slit in the present invention in FIG. A description will be given with reference to the light ray passing range of the shape and the example of the output spectrum of the spectroscope in FIG.

An outline of the operation of the present invention will be described. Slit 1
At position 7, a vertical slit 19 is provided for restricting and deleting light rays in the Y-axis direction. Thereby, the vertical slit is
In FIG. 2B, the light spots in the spots 32 and 33 in the spot shape are shielded and deleted. As a result, the spectral resolution characteristics of the light converted into the electric signal by the photodetector 18 are further improved.

The spot shape shown in FIG. 2B shows an example of the spot shape on the slit 17 after a single wavelength is incident and passes through the aperturer, as described above.

Conventionally, after the light beam having the entire beam shape shown in FIG.
At step 8, it was converted to an electric signal. However, looking at the beam spot in FIG. 2B, it can be seen that the spectral resolution can be further improved if the regions of the light spots 32 and 33 can be deleted. Therefore, in the present invention, a vertical slit 19 for removing light spots in the 32 and 33 areas discrete from the Y axis is newly provided.

That is, in the conventional slit, all the light on the Y-axis passes as in the slit range 35 on the Y-axis in FIG. 2C. Therefore, Δ slightly shifted from the center wavelength
A light spot is also detected at the position of λ. That is, FIG.
The light spots in the 32 and 33 regions (b) pass through the slit 17 even at the point Δλ. For this reason, it was detected and output by the photodetector.

On the other hand, according to the present invention, as shown in FIG.
Limited as in 6. This corresponds to 32 and 33 in FIG.
Is deleted, and light rays in only 31 areas are passed. That is, at point Δλ, 32 and 33 light spots are blocked, and are not detected by the photodetector. As a result, the attenuation on both sides is remarkably improved as shown in the spectrum waveform of FIG.

For example, what was conventionally a spectrum waveform 41 is now a spectrum waveform 42 according to the present invention.
This improvement is about 5 db or more. This is because the output level at the center wavelength is the same light output level because there is no spot portion blocked by the vertical slit. However, the light output level at a position deviated from the center wavelength is 32
And only the light output from which the light spots in the region 33 are deleted. As a result, adjacent spectrum waveforms on both sides of the center wavelength are attenuated by 5 db or more.

The above effect can be obtained only by the two cooperative actions of providing the aperture unit 13 in the diffraction grating to convert the spot shape as shown in FIG. 2B and providing the vertical slit. Improvements have become feasible.

Here, the arrangement structure of the vertical slit will be described. The slit width is, for example, 0.1 to 0.1.
Make it about 5 mm. Further, even if the slit 17 is installed at a position slightly deviated from the focal length, the effect of defocusing on the light blocking performance is small, and thus the slit 17 can be installed on the entire surface or adjacent to the rear surface. Therefore, the vertical slit can be easily provided without adding a new optical lens.

In the example shown in FIG. 1, in order to reduce the size of the spectrometer, a light beam is reflected by using a parabolic mirror, and a vertical slit 19 is provided adjacent to the conventional slit 17. However, the same functions and effects as those described above can be obtained with the following configuration means.

In the first example, as shown in the example of the spectroscopic device constituted by the lens in FIG. 4A, it is obvious that the spectroscopic device may be constituted by using a lens instead of a parabolic mirror. is there. That is, instead of using the parabolic mirror 12, the lens 1
The incident light beam may be converted into a parallel light beam using 2a. Alternatively, the parallel rays split by using the lens 16a instead of the parabolic mirror 16 may be collected and focused.

In the second example, the vertical slit 19 is provided adjacent to the conventional slit 17, but as shown in FIG. 4B, an additional lens is provided to provide a vertical slit at the focal position. You may comprise. That is, a new lens 21 is provided after the slit 17 to focus. Then, a vertical slit 19 is provided at the focal position. After that, an arrangement structure in which the photodetector is placed is adopted.

In the third example, as shown in an example in which the vertical slit is closely attached to the photodetector in FIG.
Is closely attached to the photodetector itself. This eliminates the need to use a plate as the material of the vertical slit, and the role of the vertical slit can be realized by, for example, bonding a light-shielding film or a light-shielding tape or applying a light-shielding paint to the detection surface of the photodetector. This condition can be used when the position of the photodetector 18 is close to the slit 17 and the deviation from the focal length is not large. Also in the case of FIG. 4B, it is clear that the photodetector and the vertical slit may be closely arranged.

[0028]

[Effect of the Invention] The present invention is configured as described above, and has the following effects. By the vertical slit 19 provided as the second slit, the light spots of the beam spot regions 32 and 33 that are vertically separated on the Y axis among the spot shapes on the slit are formed.
Shielded and removed. As a result, the resolution of the spectrum that passes through the slit and is converted to an electric signal by the photodetector is
It is further improved.

The output level at the center wavelength does not decrease because it is not shielded by the vertical slit. On the other hand, the light output level at a position deviating from the center wavelength is only the light output of the area 31 where the light spots of the areas 32 and 33 are deleted.
As a result, the adjacent spectral waveforms on both sides of the center wavelength have an attenuation effect of 5 db or more.

An advantage that the above-described performance improvement effect is realized by two cooperative actions of providing the diffraction grating with the aperture unit 13 to convert the spot shape as shown in FIG. 2B and providing the vertical slit. Is obtained.

[0031]

[Brief description of the drawings]

FIG. 1 is an example of a configuration diagram of a spectroscopic device of the present invention.

FIG. 2 shows a beam shape (a) incident on a diffraction grating, a spot shape on a slit (b), a light beam transmission range of a conventional slit shape (c), and a light transmission range of a slit shape of the present invention (d). And (f) of an output spectrum example of the spectroscope.

FIG. 3 is an example of a configuration diagram of a conventional spectroscopic device.

FIG. 4 shows an example (a) of a spectroscopic device constituted by a lens, and (b) an example in which a vertical slit is provided at a focal position by adding a lens.
FIG. 7C is a diagram illustrating an example (c) in which a vertical slit is disposed in close contact with a photodetector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Optical fiber 12, 16 Parabolic mirror 13 Opener 14 Diffraction grating 15 Rotation mechanism 17 Slit 18 Photodetector 19 Vertical slit

Claims (1)

(57) [Scope of request for utility model registration] By 1. A rotation for grating, the direction of <br/> wavelength sweep of the incident beam and the X-axis direction, in a spectroscopic apparatus for measuring an optical spectrum, windows for converting X-axis direction of the beam spot shape In the light path
The direction orthogonal to the X-axis direction for wavelength sweeping is set to the Y-axis direction.
MukaiToshi, shield shape windowsill in the Y-axis direction is not parallel to the Y axis
A sawtooth shape, the transmittance of the portion of the window 1, opener transmittance of the outer portion of the window is 0 and (13), the slit portion that sets the resolution of the optical spectrum, the open
A spectroscopic device comprising: a vertical slit (19) for blocking a beam spot diffracting in a side direction of a slit (17) , which appears when a mouth device changes a beam spot shape .