CN101738664B - Method for precise control of grating constant in process of manufacturing plane grating - Google Patents

Abstract

The invention provides a method for precise control of a grating constant in a process of manufacturing a plane grating. An adopted device comprises a light source, a space filter, a concave mirror, a third reflector, a fourth reflector, a convex lens and a receiving screen, wherein the space filter, the concave mirror, the third reflector and the fourth reflector are positioned on a light path of the light source in sequence; the convex lens is positioned at an exposure position; and the receiving screen is positioned on a back focus plane of the convex lens. The method comprises the steps of: making two parallel light beams which generate interference fringes pass through the convex lens by the third and fourth reflectors; generating two focusing light spots on the receiving screen which is arranged at the position of the focal distance of the convex lens; measuring a distance L between the two focusing light spots; calculating the required grating constant d according to a following formula; and adjusting an angle alpha of two parallel light beams which are formed by the third and fourth reflectors to change the distance L between the two light spots on the receiving screen so as to obtain different grating constants d. The method for the precise control of the grating constant in the process of manufacturing the plane grating ensures convenient adjustment in the manufacturing of the gratings in different periods and high grating period control precision.

Description

In plane grating manufacturing process, accurately control the method for grating constant

Technical field

The invention belongs to the spectral technique field, particularly a kind of method of in plane grating manufacturing process, accurately controlling grating constant.

Background technology

One of very important technical indicator of diffraction grating---the grating cycle is determining the dispersive power and the resolution of grating.For spectral instrument, the change of grating constant will cause the change at optical grating diffraction angle, make the spectral instrument position of spectral line produce skew, and therefore, the accuracy of grating constant directly influences the wavelength accuracy of spectral instrument, must strict control in manufacturing process.

In the manufacturing process of holographic grating, the technological process of a key is exactly the grating substrate that scribbles photoresist to be placed in the interference field, by the interference fringe in the photoresist record interference field.When exposure wavelength one timing, unique angle that is decided by two bundle directional lights of cycle.The method in conventional sense cycle generally all is after finishing preparing grating, calculate the grating cycle by the angle of measuring 0 grade on grating and 1 order diffraction light, measuring error is bigger, the light path adjustment process does not have fixing benchmark to comply with, only adjust by rule of thumb, often to pass through a plurality of preparing grating bouts, and be difficult to meet the requirements of precision.

In addition, aspect relevant patent documentation formerly, as Chinese invention patent case (publication number CN 1544994 A), by in the holographic grating exposure device, inserting standard machine engraving grating and half-reflecting mirror, from the collimating mirror light path, tell light path again, make it produce interference fringe, this can cause the needed grating cycle to depend on the standard machine engraving grating of being inserted fully, implements in the control grating cycle to have inconvenience.

Summary of the invention

The objective of the invention is to, a kind of simple and easy to do method of accurately controlling grating constant in plane grating manufacturing process is provided.

The present invention adopts following technical scheme:

The present invention also provides a kind of method of accurately controlling grating constant in plane grating manufacturing process, adopts as lower device:

Light source and being positioned at successively on the light path of described light source:

Spatial filter;

Concave mirror, described spatial filter are positioned at place, described concave mirror focal position;

The 3rd catoptron and the 4th catoptron;

Convex lens are positioned at the exposure position place;

Receiving screen is positioned on the back focal plane of described convex lens;

Wherein, described the 3rd catoptron and the 4th catoptron are used for interference fringe directional light that reflects one respectively reflects by described concave mirror in described convex lens;

May further comprise the steps:

Step 1), make generation by the 3rd catoptron and the 4th catoptron two bundle directional lights of interference fringe by described convex lens, on the receiving screen that is positioned at described focal length of convex lens place, produce two and converge focus spot;

Step 2), measure the distance L of these two focus spot, calculate required grating constant d according to following formula:

$d=\frac{\mathrm{\λ}\sqrt{4f^2+L^2}}{2L}$

Wherein, f is the focal length of convex lens, and λ is the optical maser wavelength that light source sends, and L is the distance between two hot spots;

The angle [alpha] of the formed two bundle parallel beams of step 3), described the 3rd catoptron of adjustment and the 4th catoptron obtains different grating constant d to change the distance L of two hot spots on the receiving screen.

Further, after described step 3), also comprise:

Step 4), taking-up convex lens are placed the grating substrate that scribbles photoresist in the position of former convex lens, and by photoresist recording interference fringe number, this number of interference fringes is the cycle of the plane grating of made.

Further, described light source is the helium cadmium laser of 441.6nm wavelength.

Further, on the light path between described light source and the spatial filter, also comprise first catoptron and second catoptron, the light that described light source sends successively after described first catoptron and second mirror reflects to described spatial filter.

The method of in plane grating manufacturing process, accurately controlling grating constant provided by the invention, easy to adjust for the grating of making different cycles, and control grating cycle precision height.

Below in conjunction with drawings and Examples the present invention is described in detail.

Description of drawings

Fig. 1 is the structural representation of the device that adopts among the inventive method embodiment;

Fig. 2 is the structural representation of the holographic grating exposure device light path among the inventive method embodiment.

Label declaration:

1 light source 5 the 3rd catoptron

2 first catoptrons 6 the 4th catoptron

3 second catoptrons, 7 concave mirrors

4 spatial filters 8 scribble the grating substrate of photoresist

9 convex lens 10 are accepted screen

Embodiment

A kind of method of accurately controlling grating constant in plane grating manufacturing process, adopt following device as shown in Figure 1 and Figure 2:

Light source 1 and being positioned at successively on the light path of described light source 1:

Spatial filter 4 comprises microcobjective and pin hole;

Concave mirror 7, described spatial filter 4 are positioned at place, described concave mirror 7 focal positions;

The 3rd catoptron 5 and the 4th catoptron 6;

Convex lens 9 are positioned at the exposure position place; Promptly scribble the place, grating substrate 8 positions of photoresist;

Receiving screen 10 is positioned on the back focal plane of described convex lens 9;

Wherein, described the 3rd catoptron 5 and the 4th catoptron 6 are used for interference fringe directional light that reflects one respectively reflects by described concave mirror 7 in described convex lens 9; After shining on the described convex lens 9 through two bundle directional lights of the 3rd catoptron 5 and the reflection of the 4th catoptron 6, on described receiving screen 10, form two hot spot A and B;

May further comprise the steps:

Step 1), make generation by the 3rd catoptron 5 and the 4th catoptron 6 two bundle directional lights of interference fringe by described convex lens 9, on the receiving screen 10 that is positioned at described convex lens 9 focal length places, produce two and converge focus spot;

Step 2), measure the distance L of these two focus spot, calculate required grating constant d according to following formula:

$d=\frac{\mathrm{\λ}\sqrt{4f^2+L^2}}{2L}$

Wherein, f is the focal length of convex lens 9, and λ is the optical maser wavelength that light source 1 sends, and L is the distance of hot spot A and B;

The angle [alpha] of step 3), described the 3rd catoptron 5 of adjustment and the 4th catoptron 6 formed two bundle parallel beams obtains different grating constant d with the distance L of hot spot A and B on the change receiving screen 10.

Further, after described step 3), also comprise:

Step 4), taking-up convex lens 9 are placed the grating substrate 8 that scribbles photoresist in the position of former convex lens 9, and by photoresist recording interference fringe number, this number of interference fringes is the cycle of the plane grating of made.

So just can conveniently regulate and make the different grating cycles, and can accurately control the grating constant d of the hologram plane grating of made.

Wherein, described light source 1 employing wavelength is the helium cadmium laser of 441.6nm.

Wherein, also comprise first catoptron 2 and second catoptron 3 on the light path between described light source 1 and the spatial filter 4, the light that described light source 1 sends enters described spatial filter 4 after described first catoptron 2 and 3 reflections of second catoptron.First catoptron 2 described in the present embodiment and second catoptron 3 adopt the substrate of glass aluminum reflector.

Wherein, described receiving screen 10 adopts common frosted glass, makes the holographic grating substrate and adopts K9 optical glass, the APR3120 type photoresist that the photoresist that applies on the K9 optical glass is produced for Germany.

In the above-mentioned steps, the calculating derivation of grating constant d is as follows:

At first, measure the distance L of hot spot A and B,, can obtain according to the frequency characteristic of optical imaging system because described receiving screen 10 is positioned on the back focal plane of described convex lens 9:

$x_1=\mathrm{\λ}{\mathrm{ff}}_{x1}=\frac{\mathrm{\λf}}{\cos {\mathrm{\θ}}_1}---\left(1\right)$

$x_2=\mathrm{\λ}{\mathrm{ff}}_{x2}=\frac{\mathrm{\λf}}{\cos {\mathrm{\θ}}_2}---\left(2\right)$

Wherein, f is the focal length of convex lens 9, and λ is the optical maser wavelength that light source 1 sends, f _X1, f _X2Be the spatial frequency of plane wave, as shown in Figure 1, x ₁, x ₂Be respectively the length of BC, CA, α is the angle (α=θ of the two light beams of generation interference fringe ₁+ θ ₂), according to △ BOC, the triangle relation of △ AOC has:

$\cos {\mathrm{\θ}}_1=\frac{f}{\sqrt{f^2+x_1^2}}---\left(3\right)$

$\cos {\mathrm{\θ}}_2=\frac{f}{\sqrt{f^2+x_2^2}}---\left(4\right)$

Solve by formula (1), (2), (3), (4):

Because λ and f are definite value, obtain x ₁=x ₂, x again ₁+ x ₂=L, that is:

$\sin \frac{\mathrm{\α}}{2}=\frac{L}{\sqrt{4f^2+L^2}}---\left(5\right)$

Again according to grating equation:

Can get grating constant d:

$d=\frac{\mathrm{\λ}\sqrt{4f^2+L^2}}{2L}---\left(6\right)$

In said apparatus,, can change the distance L of hot spot A and B on the receiving screen 10, thereby obtain different grating constant d by adjusting the angle [alpha] of the formed two bundle parallel beams of described the 3rd catoptron 5 and the 4th catoptron 6.

Claims (4)

1. accurate method of control grating constant in plane grating manufacturing process is characterized in that: adopt as lower device:

Light source (1) and being positioned at successively on the light path of described light source (1):

Spatial filter (4);

Concave mirror (7), described spatial filter (4) are positioned at place, described concave mirror (7) focal position;

The 3rd catoptron (5) and the 4th catoptron (6);

Convex lens (9) are positioned at the exposure position place;

Receiving screen (10) is positioned on the back focal plane of described convex lens (9);

Wherein, described the 3rd catoptron (5) and the 4th catoptron (6) are used for interference fringe directional light that reflects one respectively reflects by described concave mirror (7) in described convex lens (9);

May further comprise the steps:

Step 1), make generation by the 3rd catoptron (5) and the 4th catoptron (6) two bundle directional lights of interference fringe by described convex lens (9), go up at the receiving screen (10) that is positioned at described convex lens (9) focal length place and to produce two and converge focus spot;

Step 2), measure the distance L of these two focus spot, calculate required grating constant d according to following formula:

$d=\frac{\mathrm{\λ}\sqrt{4f^2+L^2}}{2L}$

Wherein, f is the focal length of convex lens (9), and λ is the optical maser wavelength that light source (1) sends, and L is the distance between two hot spots;

The angle [alpha] of the formed two bundle parallel beams of step 3), adjustment described the 3rd catoptron (5) and the 4th catoptron (6) obtains different grating constant d to change the distance L of last two hot spots of receiving screen (10).

2. the method for accurately controlling grating constant in plane grating manufacturing process according to claim 1 is characterized in that:

After described step 3), also comprise:

Step 4), taking-up convex lens (9) are placed the grating substrate (8) that scribbles photoresist in the position of former convex lens (9), and by photoresist recording interference fringe number, this number of interference fringes is the cycle of the plane grating of made.

3. the method for accurately controlling grating constant in plane grating manufacturing process according to claim 1 is characterized in that:

Described light source (1) is the helium cadmium laser of 441.6nm wavelength.

4. the method for accurately controlling grating constant in plane grating manufacturing process according to claim 2 is characterized in that:

Also comprise first catoptron (2) and second catoptron (3) on the light path between described light source (1) and the spatial filter (4), the light that described light source (1) sends is the described spatial filter (4) extremely through described first catoptron (2) and second catoptron (3) reflection back successively.

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