JPS6385503A - Diffraction grating - Google Patents

Abstract

PURPOSE:To improve the correction of aberration by using astigmatic light for recording light and forming a grating pattern by changing the distances from the light source points in the directions horizontal and vertical to a diffraction grating up to a grating substrate in the direction of a recording beam. CONSTITUTION:The spherical diffraction grating substrate 7, a spherical mirror 8 having 0.6132 radius of curvature, a troidal mirror 9 having 0.6132 radius of curvature in a horizontal direction and 0.5852 radius of curvature in a vertical direction and laser light sources 10, 11 which emit spherical waves are provided. Marks ''circled X, marks ''circled dot'' are respectively the focuses by the concave mirrors 8, 9 of the laser light source points 10, 11 in the horizontal and vertical directions. The recording by the astigmatic light; i.e., the recording of the grating pattern by substantially changing the distances from the points 10, 11 in the horizontal and vertical direction of the diffraction grating up to the substrate in the beam direction of the recording light is thereby executed.

Description

DETAILED DESCRIPTION OF THE INVENTION 0) Industrial Application Field The present invention relates to an nf'C diffraction grating produced by holography.

(b) Conventional concave diffraction grating? In a spectrometer, aberrations appear in the imaging performance of the concave diffraction grating, but in order to correct such aberrations, a special pattern is created as the grating pattern of the concave diffraction grating using holography. Things are being implemented. However, in the past, a spherical wave was used for recording light to form a grating pattern on a grating substrate, so the grating pattern was limited to the intersection group of the rotational hyperbola group and the grating substrate.
, it was not possible to sufficiently correct aberrations. In particular, in spectrometers that use photographic plates or array detector sounds, correction of aberrations in the dispersion direction, making the imaging surface closer to a flat surface, and ensuring that the center of the imaging surface is roughly between the centers of the diffraction gratings and the like, etc. It is necessary to create a corrector with better imaging characteristics that meet the requirements for use. 9. For example, astigmatism, although the effective efficiency decreases, correction of aberrations in this direction is not performed. is the actual situation.

In addition, in the conventional planar diffraction grating, the grating grooves are made by cutting grooves, and the grating pattern is an evenly spaced 100-kachi grating. In a spectrometer that uses a concave 07] section as a premeter element, a spherical ill is used as the concave surface and is used in an off-axis state, so aberrations are caused by these concave mirrors. The ninth step to correcting this aberration is to make the grating pattern of the plane diffraction grating special and generate an aberration in the second diffraction grating that cancels the aberration caused by the collimator mirror and camera mirror.
However, even in this case, such a special lattice pattern can be created by using holography. However, since a spherical wave was still used for the recording light, aberration correction was insufficient.

(c) Problems to be Solved by the Invention The present invention attempts to improve the formation of a grating pattern of a diffraction grating using holography to enable more complete aberration correction.

(b) Means for Solving the Problem The diffraction grating of the present invention uses nine horizontal directions of the diffraction grating on the nine-line direction of recording light for recording a diffraction grating pattern on a diffraction grating substrate by holography.

The entire feature is that the distance from the vertical diverging light source point to the grating substrate is substantially changed.

(E) The method for creating a diffraction grating pattern using action holography is to project the elements of binary fluxes that can interfere with each other onto a nine-diffraction grating substrate to form the entire diffraction grating pattern, and record this interference pattern by printing on the substrate surface. The above-mentioned binary flux is called recording light, and its light source is called a recording light source. Conventionally, a plane wave region or a spherical wave has been used as the above two recording lights. On the other hand, in the present invention, the distance from the diverging light source point of the diffraction grating in the horizontal and vertical directions to the diffraction grating substrate is substantially changed in the direction of the recording light beam, so that the beam direction of the recording light beam ( Astigmatic original, astigmatic party) was used as the recording light.

Since the parameters of the recording conditions for forming the interference pattern have increased from this nK, the resulting interference pattern is also rich in variation, and the degree of freedom in selecting the interference pattern has increased, so by selecting the conditions described above, aberration correction can be improved compared to the conventional method. became more complete.

The reason why the parameters of recording conditions increase is that when using a spherical wave, the only parameter is data on the position of the point light source, but when Astigmatic 51f is used, the position of the point light source in the horizontal and vertical directions increases. The parameters of the recording conditions, especially those related to the vertical imaging conditions, will be substantially different from the intensifier, thereby reducing the effects of aberrations, especially astigmatism, in the optical system of the spectrometer as a whole. This means that it can be corrected.

(f) Example (Using a spherical diffraction grating substrate) Fig. 2 is a diagram showing the layout of a conventional spherical diffraction grating when recording a grating pattern, and 4 is a hologram 4'') to produce interference fringes. A spherical diffraction grating substrate coated with a photosensitizer to be recorded and made into a 9-diffraction grating, 5 and 6 are laser light source points that generate a spherical wave t.In this case, a rotational hyperbola group with one source point 5.6 as the focal point. A stripe is generated at the intersection line between the laser beam and the substrate.The specific recording conditions in this case are one using a laser beam with a wavelength of 441.6 nm.

rc”=0.9896, I=−4,7
64rD: 0.9908 + δ= 10.101
'Figure 1 has the same horizontal (dispersion) focal line as the conventional refraction grating shown in Figure 2 (8), and in order to correct astigmatism, the vertical focal line becomes the horizontal focal line. The next section shows the arrangement of the grating patterns of the diffraction gratings of the present invention, which form a grating pattern of the diffraction gratings (see FIG. 3) that intersect approximately at the center of the gratings. 7 is a spherical diffraction grating substrate, 8 is a 61320 spherical mirror with a radius of curvature of 0°, and 9 is a horizontal radius of curvature of 0.6.
132° is a toroidal mirror with a radius of curvature of 0.5852 in the vertical direction, and 10.11 is a laser light source point that emits a spherical wave. The specific recording conditions in this case are that the laser wavelength is 44
When using a 1.6 nm laser source, pc = 1.5819
, qc=0.5923, rc=15
．． 000'ri D=1.5831 t qD depth 0.5
923, τo = 15.000°. ■ and ■ marks in the figure are the laser light source points 1 in the horizontal and vertical directions, respectively.
This is the focal point of the concave mirrors 8 and 9 with a diameter of 0.11, and this allows recording based on the stigmatized source, that is, the σJ trace from the source point in the horizontal and vertical directions of the diffraction grating to the grating substrate in the same direction as the recording light beam. In this humiliating appearance, Kueva I-So's imperial edict can be performed.

An example of a spectroscopic system using the diffraction grating of the above embodiment is shown in Fig. kM3. 1 is an artificial slit, 2 is a diffraction grating according to the present invention,
3 is the photographic plate or array detector surface, wavelength range 350
It is installed at a position where the deviation from the focal line in the horizontal (dispersion) direction is minimized in the range from nm to 750 nm. The arrangement of the spectroscopic system is the third one.
In the figure, r=0.9514, α=19.2
681'+=1.0035, ! +=-7.1
64°rz=1.0104, /2=6.
At 309 degrees, the horizontal radius of curvature of the diffraction grating 2 is 1
It is ゜000.

(When fc is used using a toroidal diffraction grating substrate) FIG. 4 is a diagram showing arrangement 2 of a grating pattern of a diffraction grating according to another embodiment of the present invention used in the same spectroscopic system as that shown in FIG. 3. The horizontal focal line and the vertical focal line are placed on the horizontal focal line of the conventional diffraction grating shown in Figure 2 (see Figure 3). In the figure, 12 is a toroidal diffraction grating substrate, 13 is a spherical mirror with a radius of curvature of 1.000, and 14.15 is a wavelength of 441.6.
This is a laser light source point that emits a nm spherical wave. The specific recording conditions are pc=1.9854, qc=0.9957
, τc=5.2889ro=0.9908,
I=-4,764°, δ=10.134°. In the figure, ■, O mark is A (horizontal by 'A laser beam focus 14,
With the vertical focal point, the distance from the horizontal and vertical light source point of the diffraction grating to the grating substrate can be substantially changed depending on the recording by the astigmatism, that is, the direction of the recording beam. This will allow you to record a grid pattern.

(When a Planar Diffraction Grating Substrate is Used) FIG. 5 is a diagram showing the arrangement of a diffraction grating according to still another embodiment of the present invention when recording a grating pattern.

24 is a plane-opening grating substrate, and 20.22 is a recording light source point.

21 is a spherical mirror with a radius of curvature of 1.0000, 23 is a radius of curvature in the horizontal direction of 1.0000 and a radius of curvature in the vertical direction of 0.938.
8 toroid/l' mirror. The specific recording conditions in this case are when a laser beam with a laser wavelength of 441.6 nm is used.

pc=1.9724, qc=0.9767
, τc=5.1211)D=2.0799 1
qD=0.9879, τo=4,9
56'1 = 33.438 δ= 1.
210'. In the diagram, laser light source points 20
It is a focal point in the horizontal and vertical directions due to the concave surface m 21123 of ゜22, and from this n, recording by the stigmatic element, that is, the distance from the light source point of the diffraction grating in the horizontal and vertical directions to the grating substrate in the direction of the recording light beam is the same as above. This means that the grid pattern can be recorded with virtually all changes.

FIG. 6 is a diagram showing an example of a spectroscopic system using the diffraction grating of the above embodiment, in which 16 is an entrance slit, 17 is a concave mirror, 18 is a diffraction grating according to the present invention, and 19 is an exit slit. The diffraction grating 18Iri is installed at a position where the deviation from the horizontal (dispersion evening parfocal) is minimized in the wavelength range of 300 to 900 nm. , the 1m folded grating 18 has a lattice constant "/1200 mm l usage r = 0.775
5, D=0.6204, r=0.70
64θ=10° 1 2 = 20°.

A. In the above embodiment, both of the two recording beams use a stigmatic source, but due to the design, only one of the two recording beams is used as a stigmatic source, that is, a stigmatic source from the light source point. In many cases, it is sufficient to change the distance to the slave board.

(G) Effect 4 Using a 4-point nine, a grating pattern was formed by substantially altering the distance from the light source point of the diffraction grating in the horizontal and vertical directions to the grating substrate in the direction of the recording beam. ) The correction of aberrations that occur is better than that of conventional reholographic diffraction gratings. In particular, it has a remarkable effect on correcting astigmatism. Figure 7 shows this effect.

Spacing old I h amount Kuji 4g) 1 to 21 ma open θ) Convex ≦-
This figure shows the spread due to aberrations when monochromatic light having several wavelengths is incident from the center of the entrance slit 1 at the dry plate surface 3 shown in FIG.

The area of the diffraction grating was 40×40 mrn. (a
) Figure shows (b) when a conventional diffraction grating (Figure 2) is used.
The figure shows the case where the diffraction grating of the embodiment of the present invention shown in FIG. 1 is used, and the figure (C) shows the case where the diffraction grating of the other embodiment of the present invention shown in FIG. 4 is used. It can be seen that vertical aberrations, that is, astigmatism, are significantly corrected in FIGS. 1B and 2E according to the present invention as compared to FIG. 1A.

[Brief explanation of the drawing]

1 is a plan view showing the arrangement of a diffraction grating according to the present invention at the time of grating pattern recording, FIG. A fourth plan view of a spectrometer using a diffraction grating according to an embodiment of the present invention.
9 is a plan view showing the arrangement of another diffraction grating according to the present invention when recording a grating pattern; FIG. 5 is a plan view showing the arrangement when recording a grating pattern of still another diffraction grating according to the present invention;
6 is a plan view of a spectrometer using the diffraction grating sound of the embodiment shown in FIG. 5, and FIG. 7 shows the performance of the diffraction grating according to the present invention. This is a graph showing the effect. 1.16...Input loss filter) 2.18...Diffraction grating 3
... Dry plate (detector 2 side 4, 7.12.24... Diffraction grating substrate 5, 6.10.
11.14.15.20.22... Recording light source point 8.2
3...Troid/L' mirror 9.13.21...Spherical mirror 17...Concave mirror 19...Output loss slit fi: Buried fF-Buried E Ei Sentence:5.・. -;1- Figure 7 650hm 750nn-

Claims (1)

[Claims] (1) In a diffraction grating that has a grating pattern produced by projecting two interfering light beams onto the surface of a diffraction grating substrate and forming an interference pattern, this interference pattern is recorded on the substrate surface. A diffraction grating characterized in that the distance from the diverging light source point in the horizontal and vertical directions of the diffraction grating to the diffraction grating substrate is substantially changed in the principal ray direction.