CN101718884B - Zero-level light optical locating method of optical grating substrate in manufacturing of plane holographic grating - Google Patents

Abstract

The invention relates to a zero-level light optical locating method of an optical grating substrate in manufacturing of a plane holographic grating, belonging to a locating method of the optical grating substrate in the spectroscopy field; the solved technical problem is that the zero-level light optical locating method of the optical grating substrate in manufacturing of the plane holographic grating is provided; the technical proposal is that: step I, a set of plane holographic grating exposure unit is allocated, and the unit is completely consistent to a holographic grating exposure unit in the prior art; step II, a monitoring laser and a reticle are additionally arranged in the plane holographic grating exposure unit, and the position of a standard optical grating is recorded on the reticle; step III, another reticle is additionally arranged, the position of a monitoring laser beam is recorded on the two reticles; step IV, the optical grating substrate is installed and regulated to lead the reflected light of the monitoring laser beam to return to the center of the reticles, at the moment, exposure is carried out to manufacture the plane holographic grating with standard grating constant. The method can rapidly and accurately locate the optical grating substrate and improve the manufacturing efficiency.

Description

Zero-order light positioning method for grating substrate in the fabrication of planar holographic gratings

technical field

The invention belongs to the field of spectrum technology and relates to a method for positioning a grating substrate in the production of a plane holographic grating. the

Background technique

In the manufacture of planar holographic gratings, the positioning accuracy of the grating substrate will directly affect the accuracy of the grating constants, and the use of zero-order light to position the grating substrate can ensure the accuracy of the grating constants. the

The planar holographic grating is made by recording the interference fringes of two coherent light beams through photoresist and then developed. The grating constant is determined by the period of the interference fringes. The period of the interference fringes when making a planar holographic grating is very small, and it is difficult to measure it directly and accurately in practice. The conventional detection method is to calculate the grating constant by measuring the angle between the 0th order and the 1st order diffracted light of the grating after the grating is manufactured. The measurement error is relatively large. There is no fixed benchmark for the optical path adjustment process, and it is only based on experience. Adjustments often have to go through multiple grating production rounds, and it is difficult to achieve the required accuracy. The existing technology closest to the present invention is Chinese Patent No. CN1544994, which proposes a method for precisely controlling the grating constant in the manufacture of a planar holographic grating. The schematic diagram of the planar holographic grating exposure device is shown in Figure 1. The light beam emitted by the laser light source 1 is reflected by the first plane mirror 2 and the second plane mirror 3, and then becomes a spherical wave after being expanded and filtered by the spatial filter 4, and the spherical wave becomes parallel light after being collimated by the collimating mirror 5 , place the fifth flat reflector 8 in the parallel light path to draw a bunch of parallel light, then reach the half mirror 10 after being reflected by the sixth plane reflector 9, adjust the sixth plane reflector 9 to pass through the half mirror Both the reflected light and the transmitted light of 10 are incident on the standard machine-engraved reflective grating 11 at the self-collimation diffraction angle. The direction goes back the same way, and after passing through the half mirror 10, the reflected light of -1 level and the transmitted light of +1 level overlap on the other side of the half mirror 10, forming interference fringes on the receiving screen 12. At this time, the fifth plane reflector 8 and the sixth plane reflector 9 and the standard machine-engraved reflective grating 11 are withdrawn and the positions of the half mirror 10 and the receiving screen 12 are kept unchanged, and the third plane reflector is placed in the parallel light beam. The mirror 6 and the fourth plane reflector 7 adjust the direction of the two beams of reflected light so that they form the same interference fringes on the receiving screen as before. Like this, the fringe period of the interference field formed by the intersection of the reflected light beams of the third plane reflector 6 and the fourth plane reflector 7 in the area where the standard engraved reflective grating 11 is placed is the same as the grating constant of the standard engraved reflective grating 11, A planar holographic grating with a standard grating constant can be produced by placing the grating substrate coated with photoresist at the position of the standard engraved reflective grating 11 for exposure and development. the

The main problem of this method is: after removing the standard machine-engraved reflective grating 11 in actual operation, it is difficult to restore the grating substrate to be exposed to the original position of the standard machine-engraved reflective grating 11. If the normal line of the grating substrate to be exposed deviates from The normal direction of the standard machine engraved reflective grating 11 will inevitably cause errors in the grating constant of the fabricated grating. The more the normal line of the grating substrate to be exposed deviates from the normal direction of the standard machine-engraved reflective grating 11, the greater the error of the grating constant of the fabricated grating. the

Contents of the invention

In order to overcome the problems existing in the prior art, the object of the present invention is to establish a simple and feasible method for precise positioning of the grating substrate using zero-order light in the manufacture of planar holographic gratings. the

The technical problem to be solved by the present invention is to provide a zero-order light positioning method for the grating substrate in the manufacture of the planar holographic grating. The technical solution to solve the technical problem is: step 1, equip a set of planar holographic grating exposure device, which is completely consistent with the holographic grating exposure device in the background technology, as shown in Figure 2, including laser light source 1, first plane reflector 2. The second plane mirror 3, the spatial filter 4, the collimation mirror 5, the third plane mirror 6, the fourth plane mirror 7, the fifth plane mirror 8, the sixth plane mirror 9, half mirror Semi-mirror 10, standard machine-engraved reflective grating 11 and receiving screen 12; the optical path structure and adjustment are completely consistent with the description in the background technology, and vertical and clearly visible interference fringes can be observed on the receiving screen 12; Step 2, in In the planar holographic grating exposure device, a monitoring laser 13 is placed on the side facing the standard engraved reflective grating 11, and a first reticle 14 is placed in front of the exit light path of the monitoring laser 13, as shown in Figure 2, the monitoring The outgoing beam of the laser 13 passes through the center of the first reticle 14 and is incident on the standard engraved reflective grating 11, and the zero-order diffracted light returns to the center of the first reticle 14 in the original path; Step 3, as shown in Figure 3, takes The standard engraved reflective grating 11, the fifth plane reflector 8 and the sixth plane reflector 9 in the following figure 2, and ensure that the positions of the half mirror 10, the receiving screen 12, the monitoring laser 13 and the first reticle 14 are consistent. At this time, the reflected light of the third plane reflector 6 and the fourth plane reflector 7 is adjusted to be superimposed after being transmitted and reflected by the half mirror 10 respectively, so that the direction and quantity of the interference fringes on the receiving screen 12 are respectively different from those of the standard machine The interference fringes produced by engraved reflective grating 11 are the same, and the second reticle 15 is placed far away on the other side of half mirror 10 in the propagation direction of the outgoing light beam of monitoring laser 13, so that the outgoing light beam of monitoring laser 13 passes through At the center of the second reticle 15, at this moment, the monitoring laser 13 is moved to the second reticle 15 rear and its outgoing light beam passes through the center of the second reticle 15 and the first reticle 14 successively; Step 4, As shown in Figure 4, take off the half mirror 10 shown in Figure 3, the receiving screen 12 and the first reticle 14, the grating substrate 16 to be made that is coated with photoresist is placed on the position of the standard machine engraving reflective grating 11 The mounting fixture of the grating base 16 is installed on a precision adjustment platform capable of adjusting rotation and pitch, and the grating base 16 is adjusted so that the outgoing light beam of the monitoring laser 13 returns to the center of the second reticle 15 through the original path of the reflected light of the grating base 16 , then exposure can produce a planar holographic grating with a standard grating constant. the

Description of the working principle of the present invention: take the machine-engraved grating with standard grating constants as a reference, make the interference fringe period consistent with the grating constant of the machine-engraved grating with standard grating constants, and adjust the grating substrate to be made to be perpendicular to the interference fringes, thereby The grating constant of the prepared planar holographic grating is the same as that of the machine-engraved grating with the standard grating constant. Step 1, adjust the sixth flat reflector 9 so that its reflected light is divided into two beams after passing through the half mirror 10, one beam is reflected light, and the other beam is transmitted light. The reflected light of the half-mirror 10 is incident on the standard machine-engraved reflective grating 11 with the +1-level self-collimation direction, and according to the principle of self-collimation, the diffracted light returns to the half-mirror 10 according to the original path of its incident direction, and half of them Pass through the half-mirror 10 to reach the receiving screen 12; the transmitted light of the half-mirror 10 is incident on the standard engraved reflective grating 11 in the -1st order self-collimation direction, and the diffracted light returns to the half-reflective grating according to its original path of incidence. Half of the lens 10 is reflected by the half mirror 10 to reach the receiving screen 12, and the two beams of coherent light beams arriving at the receiving screen 12 are superimposed to form interference fringes. Step 2: Place the monitoring laser 13 on the side facing the standard machine-engraved reflective grating 11, so that the outgoing light is incident on the standard machine-engraved reflective grating 11 through the center of the first reticle 14, and the zero-order diffracted light passes through the original path Return to the center of the first reticle 14 . Step 3, remove the standard machine-engraved reflective grating 11, the fifth plane reflector 8 and the sixth plane reflector 9, and replace the standard machine-engraved reflective grating 11 with the reflected light of the third plane reflector 6 and the fourth plane reflector 7 +1 order and -1 order diffracted light under the self-collimation state, the reflected light of the 3rd plane reflector 6 reaches the receiving screen 12 through the half mirror 10, the reflected light of the 4th plane reflector 7 passes through the half mirror half mirror 10 is reflected and reaches the receiving screen 12, and the two beams of light interfere to form interference fringes. The coherent light obtained by step 1 and step 3 has the same propagation direction and optical path difference, and must have the same interference fringes. Place the second reticle 15 far away on the other side of the semi-mirror 10 in the outgoing light beam propagation direction of the monitoring laser 13, so that the outgoing light beam of the monitoring laser 13 passes through the center of the second reticle 15, so that the first The direction of the connecting line between the centers of the reticle 14 and the second reticle 15 is the normal direction of the standard machine-engraved reflective grating 11, and the monitoring laser 13 is moved to the rear of the second reticle 15 so that its outgoing light beam passes through the second reticle successively. The center of the second reticle 15 and the first reticle 14. Step 4, remove the half mirror 10, the receiving screen 12 and the first reticle 14, place the grating substrate 16 coated with photoresist to the position of the standard machine-engraved reflective grating 11, adjust the rotation of the grating substrate 16, The pitch makes the reflected light of the laser beam incident on the grating substrate 16 by the monitoring laser 13 return to the center of the second reticle 15, so that the normal of the grating substrate 16 is in the same direction as the normal of the standard machine-engraved reflective grating 11, thereby producing The grating constant of the planar holographic grating is the same as that of the standard machine-engraved reflective grating 11. the

The positive effect of the present invention: the interference fringe period of the interference field in the planar holographic grating exposure device can be adjusted quickly and accurately, and the interference fringe period can be accurately transferred to the grating substrate coated with photoresist, thereby greatly improving the performance of the planar holographic grating The precision of the grating constant. the

Description of drawings

Figure 1 is a schematic diagram of the optical path structure and interference fringe adjustment of a planar holographic grating exposure device in the prior art;

Fig. 2 is a schematic diagram of the optical path structure of the planar holographic grating exposure device and the zero-order light positioning device in the present invention;

Fig. 3 is from the optical path shown in Fig. 2 and removes the interference optical path and the zero-order light positioning device schematic diagram formed after the fifth plane reflector 8, the sixth plane reflector 9 and the standard machine-engraved reflective grating 11;

FIG. 4 is a schematic diagram of removing the half-mirror 10, the receiving screen 12 and the first reticle 14 in the optical path shown in FIG. 3, placing the grating substrate 16 to be fabricated into the interference field and performing zero-order light positioning. the

Detailed ways

The present invention is implemented according to the optical path structure shown in Figures 1, 2, 3, and 4 and by the method steps of the above-mentioned steps 1, 2, 3, and 4. The laser light source 1 adopts a krypton ion laser with a wavelength of 413.1 nm, and the first plane reflection The mirror 2, the second plane mirror 3, the third plane mirror 6, the fourth plane mirror 7, the fifth plane mirror 8 and the sixth plane mirror 9 are all aluminum-plated mirrors on glass substrates, and the spatial filter 4 Composed of a microscopic objective lens and a pinhole, the diameter of the collimating mirror 5 is φ320mm, the focal length is 1.2m, the semi-reflective half-mirror 10 is a thin semi-reflective and semi-transmissive beam-splitting lens, and the standard machine-engraved reflective grating 11 has a groove density The receiving screen 12 is made of ordinary white frosted glass, the monitoring laser 13 is made of He-Ne laser, the output wavelength is 632.8nm, the first reticle 14 and the second reticle 15 are transparent circles marked with a cross Plate, the grating substrate 16 adopts K9 optical glass, and the photoresist coated on the K9 optical glass is Shipley 1805 type photoresist produced in Japan. the

Claims (1)

1. The zero-order light positioning method of the grating substrate in the production of a planar holographic grating, which is realized by using a planar holographic grating exposure device, and is characterized in that: step 1, a set of planar holographic grating exposure devices is equipped, including a laser light source (1) , the first plane mirror (2), the second plane mirror (3), the spatial filter (4), the collimating mirror (5), the third plane mirror (6), the fourth plane mirror (7 ), the fifth plane reflector (8), the sixth plane reflector (9), half mirror (10), standard machine-engraved reflective grating (11) and receiving screen (12); the laser light source (1) sends The light beam is reflected by the first plane mirror (2) and the second plane mirror (3), and then beam expanded and filtered by the spatial filter (4) to become a spherical wave, and the spherical wave is collimated by the collimating mirror (5) Become parallel light, place the fifth plane reflector (8) in the parallel light path to draw a bunch of parallel light, then reach the half-mirror half mirror (10) after being reflected by the sixth plane reflector (9), adjust the sixth plane reflection The mirror (9) makes the reflected light and the transmitted light through the half-mirror (10) incident on the standard machine-engraved reflective grating (11) at a self-collimated diffraction angle, and the two beams of light pass through the standard machine-engraved reflective grating (11 ) after the ±1-order self-collimation diffraction, respectively return by their original path of incident direction, and then through the half mirror (10), the reflected light of -1 order and the transmitted light of +1 order are in the half mirror The other side of (10) overlaps, and can observe vertical and clearly visible interference fringes on the receiving screen (12); Step 2, in the planar holographic grating exposure device, engrave the reflective grating (11) on the standard machine One side of the monitoring laser (13) is equipped with a monitoring laser (13), and the first reticle (14) is placed in front of the exit light path of the monitoring laser (13), and the outgoing light beam of the monitoring laser (13) passes through the first reticle (14) ) center is incident on the standard engraved reflective grating (11), and the zero-order diffracted light returns to the center of the first reticle (14) in the original path; Step 3, from the optical path structure of the planar holographic grating exposure device and the zero-order light positioning device Remove the standard machine-engraved reflective grating (11), the fifth flat mirror (8) and the sixth flat mirror (9), and ensure that the half mirror (10), receiving screen (12), monitoring laser (13) And the position of the first reticle (14) is constant, at this moment adjust the reflected light of the 3rd plane reflector (6) and the 4th plane reflector (7) that is placed in the parallel light path through the semi-reflection half mirror respectively (10) superposition after transmission and reflection, so that the direction and quantity of the interference fringes on the receiving screen (12) are identical with the interference fringes produced by the standard machine-engraved reflective grating (11) respectively, and the output beam of the monitoring laser (13) Place the second reticle (15) far away on the other side of the semi-anti-half mirror (10) in the propagation direction, so that the outgoing light beam of the monitoring laser (13) passes through the center of the second reticle (15), at this time Move the monitoring laser (13) to the second reticle (15) rear and make its outgoing light beam pass through the center of the second reticle (15) and the first reticle (14) successively; Step 4, Take off the half mirror (10), receiving screen (12) and the first reticle (14), the grating base (16) to be made that is coated with photoresist is placed on the position of the standard machine engraved reflective grating (11), The mounting fixture of the grating base (16) is installed on a precision adjustment platform capable of adjusting rotation and pitch, and the grating base (16) is adjusted so that the outgoing light beam of the monitoring laser (13) returns to the first path through the reflected light of the grating base (16). The center of the reticle (15) is exposed at this time to produce a planar holographic grating with a standard grating constant.

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