US3622411A - Method of manufacturing an elongated composite diffraction grating - Google Patents

Method of manufacturing an elongated composite diffraction grating Download PDF

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Publication number
US3622411A
US3622411A US662433A US3622411DA US3622411A US 3622411 A US3622411 A US 3622411A US 662433 A US662433 A US 662433A US 3622411D A US3622411D A US 3622411DA US 3622411 A US3622411 A US 3622411A
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grating
gratings
replica
diffraction grating
substrate
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Kiyozo Koshiishi
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1847—Manufacturing methods

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  • An economical method of manufacturing an elongated composite diffraction grating in mass production with the aid of a combination of a plurality of steps comprises replicating from a master diffraction grating a number of replica difi'raction gratings, clamping the replica diffraction gratings in a jig with one of them being made stationary while the other is made adjustable so as to bring it into coincidence with the stationary one in direction and phase, and mechanically securing or cementing the gratings together,
  • the invention relates to a method of manufacturing an elongated composite diffraction grating comprising at least two replica diffraction gratings.
  • An object of the invention is to obviate the above disadvantages and provide an improved method of manufacturing a composite diffraction grating, and which is particularly adapted to be applied in mass production in a less expensive manner.
  • Another object of the invention is to provide a method of manufacturing an elongated diffraction grating adapted to be utilized for accurate measurement which makes use of a moire fringe and for automatically controlling machine tools etc.
  • a feature of the invention is the provision of such an improved method of manufacturing an elongated composite diffraction grating which comprises in combination replicating from a master diffraction grating a number of replica diffraction gratings, clamping these replica diffraction gratings side by side in a spaced relation in a jig and making one of the gratings stationary while the other is adjustable so as to bring the other grating into coincidence with the stationary grating in direction and phase, and mechanically securing or cementing these replica gratings together to form an elongated composite diffraction grating.
  • FIG. 1 is a perspective view showing a master diffraction grating to be used in the method according to the invention
  • FIG. 2a is a diagrammatic plan view of a substrate of a replica diffraction grating and FIG. 2b is its longitudinal section;
  • FIG. 3a is a diagrammatic plan view of a modified form of the substrate of the replica diffraction grating and FIG. 3b is its longitudinal section;
  • FIG. 4 is a diagrammatic illustration of a step of the method according to the invention.
  • FIG. 5 is a longitudinal section showing a replica diffraction grating obtained by the step of the method according to the invention as illustrated in FIG. 4;
  • FIG. 6 is a longitudinal section showing a modified form of the replica diffraction grating shown in FIG. 5;
  • FIG. 7 is a diagrammatic illustration of another step of the method according to the invention.
  • FIG. 8 shows a moire fringe produced at the junction of two laminated gratings in enlarged scale
  • FIG. 9 illustrates the phases of light ray diffracted by two gratings
  • FIG. 10 shows a composite diffraction grating obtained by the method according to the invention with the joint being shown in section;
  • FIG. 11 shows a modified composite diffraction grating obtained by the method according to the invention with the joint being shown in section;
  • FIG. 12 is a longitudinal section of an elongated composite diffraction grating obtained by the method according to the invention.
  • FIG. 13 shows a diffraction grating whose gratings are inclined by an angle from the vertical
  • FIG. 14 is a diagrammatic illustration of a method of testing the accuracy at the junction of a composite diffraction grating with the aid ofa moire fringe;
  • FIGS. 15 and 16 show moire fringes produced at the junction in different states
  • FIG. 17 is a curve illustrating a buildup pitch error in a conventional composite diffraction grating
  • FIGS. l8, l9 and 20 illustrate a method of manufacturing a composite diffraction grating having substantially no built-up pitch error according to the invention.
  • FIG. 21 shows a curve illustrating a builbup pitch error of a composite diffraction grating obtained by the method illustrated in FIGS. 18, 19 and 20.
  • 1 designates a grating surface of a diffraction grating formed on its substrate 2 and having a length L
  • diffraction grating 1, 2 as a master from which a number of replica diffraction gratings are replicated.
  • substrates 3 and 4 shown in FIGS. 2 and 3 are used as substrates for supporting replica diffraction grating surfaces to be formed thereon.
  • the length L of these substrates 3 and 4 is made shorter than the length L of the grating surface I so as to form the replica grating surface throughout the surface of the substrates 3 and 4.
  • the substrates 3 and 4 are subjected to machining so as to make the substrate 3 rectangular and the substrate 4 a parallelogram in longitudinal section and make the angle between the side and end edges of each of those surfaces of the substrates 3 and 4 on which the replica is to be formed right angles.
  • the invention makes use of an inverted L-shaped jig 5 having two vertical surfaces 5' and 5" at different levels as shown in FIG. 4. Then, the substrate 2 of the master diffraction grating is put on a horizontal base plate 6 on which the jig 5 is mounted with the two surfaces 5 and 5 thereof being directed vertically. The end surface of the substrate 2 abuts against the lower surface 5" of the jig 5. Subsequently, synthetic resin 7 is flowed over the master grating surface 1 and on the synthetic resin is placed the substrate 3 shown in FIG. 2 with its end surface being abutted against the upper surface 5 of the jig 5, thereby forming a resin replica grating 8 shown in FIG. 5. Then, the substrate 3 with its resin replica grating 8 is separated from the master grating surface I after the resin has been hardened.
  • the jig 5 shown in FIG. 4 is capable of obtaining a number of replica gratings whose gratings are inclined in the same direction as those of the master grating 1.
  • the gratings of the replica diffraction grating are inclined by the same angle from the end surface of its substrate.
  • FIG. 6 shows a replica grating 9 formed on the parallelogram-shaped substrate 4 shown in FIG. 3.
  • the thus obtained replica diffraction grating 3, 8 shown in FIG. 5 is clamped in a channel-shaped jig 10 through a razor blade 11 by means of a screw 12 in a manner such that one of the end and side surfaces of the replica grating 3, 8 abuts against the inner end and side surfaces of the jig 10.
  • another replica diffraction grating 3', 8' is adjustably clamped in the jig 10 by means of a pivot 13 projected from the inner surface of the jig 10, two screws 14 and 15 abutting against those parts of one side surface of the substrate 3 which are located across the pivot 13 and a micrometer 16 abutting against one end surface of another grating 3, 8' through a razor blade 17, the another end surface of the grating 3, 8 being spaced a short distance from the opposite end surface of the grating 3, 8 to form a gap g. 18 designates a place for holding the micrometer 16.
  • another diffraction grating 19 having a pitch which is the same as the pitches of the replica diffraction gratings 8, 8' is placed on the latter across the gap g to form a moire fringe.
  • the screws 14 and 15 are accurately adjusted so as to bring the pitch W of the moire fringe produced from the diffraction gratings l9 and 8' into coincidence with the pitch w of the moire fringe produced from the diffraction gratings l9 and 8 thus making the gratings of both gratings of diffraction gratings 8 and 8 parallel to each other.
  • the invention is capable of manufacturing a replica diffraction grating having gratings inclined by the same angle from the end surface of its substrate so that the above-mentioned difference of the pitches of the moire fringes becomes rather small.
  • it is simple to make the gratings 8 and 8 parallel to each other by adjusting the screws 14 and 15.
  • the thus adjusted gratings 8 and 8' are mechanically secured together or cemented together with the aid of the synthetic resin to form a composite diffraction grating.
  • An elongated diffraction grating having any desired length can be obtained by securing further replica diffraction gratings one by one in a similar manner to the diffraction gratings 8 and 8 secured or cemented together as above explained.
  • Another feature of the invention lies in that the composite diffraction grating obtained by the step explained with reference to FIG. 7 is used as a master, and a replica composite diffraction grating is formed on such master.
  • the thus replicated composite diffraction grating is shown in FIG. 12 in which 26 designates gratings and 27 shows a substrate common to a number of gratings 26.
  • the invention provides an economical way of manufacturing an elongated composite diffraction grating in mass production with the aid of a combination of a plurality of steps without incurring great expense and without using a specially designed ruling machine, and can be applied conveniently to the accurate measurement which makes use of the moire fringe and to automatic control of machine tools etc.
  • a further feature of the invention is that use is made of a zero-biassed diffraction grating, that is a diffraction grating whose gratings are all parallel with the line vertical to the side surface of the substrate, thus eliminating built-up pitch error to be explained hereinafter.
  • a diffraction grating adapted for use in measuring instruments which make use of the moire fringe must be accurate not only in its relative pitch, but also in its absolute pitch value.
  • the gratings 1 of such diffraction grating therefore, are inclined by a small angle 4, from a line 28 vertical to the side surface of the substrate 2 for the purpose of adjusting the absolute pitch value as shown in FIG. 13.
  • a desired grating constant w is given by the following formula
  • two diffraction gratings 29 and 30 each having a pitch constant w are arranged side by side with a gap g being formed therebetween and another diffraction grating 31 having also a pitch constant w is placed across the gap 3 to form a moire fringe as shown in FIG. 14.
  • the invention makes it possible to adjust the grating 30 with respect to the grating 29 and in the manner as explained with reference to FIG. 7, with the result that the gap g at the junction becomes a positive integer times larger than the grating constant w and that the gratings 29 and 30 become parallel to each other.
  • the displacement of the moire fringe at the junction g is eliminated and the pitches of the moire fringe become equal.
  • the detectable displacement of the moire fringe is W/ even when a magnifying optical lens system is used,
  • one of the moire pitches overlaps the other moire pitch by W/ ID as shown in FIG. 16.
  • the pitches of the moire fringe W and W are represented by the following formulas From the above formula (4)
  • the biasing angle becomes large
  • Ag also becomes large thus making the gratings at both sides of the junction not parallel.
  • the composite diffraction grating is much influenced by Aw.
  • a typical built-up pitch error produced in the above mentioned composite diffraction grating is shown in FIG. 17.
  • the invention makes use of a number of replica diffraction gratings 32, 33 each having no biassed gratings 32 and manufactured, for example, by the step explained with reference to FIG. 4. Then, a composite diffraction grating 32, 33, 32', 33, with zero biassed gratings are replicated onto a substrate 34 as shown in FIG. 19.
  • the composite replica diffraction grating thus manufactured has the advantages that even if the pitches at both sides of the junction g is different by W/ 10, for example, each, other A5 is smaller than that of the composite diffraction grating consisting of the biassed gratings as can be seen from the formula (8 and that Aw is less influenced since tang, is zero or substantially zero.
  • the composite diffraction grating 35, 36 manufactured by using the above mentioned zero biassed gratings and shown in FIG. 20 has substantially no built-up pitch error as shown in FIG. 21.
  • the method according to the invention renders it possible to manufacture a composite diffraction grating having an improved grating accuracy contrary to the conventional method of manufacturing a composite diffraction grating consisting of biassed gratings.
  • a method of manufacturing a composite diffraction grating comprising the steps of arranging a plurality of gratings replicated from a common master grating in edge to edge relation beside one another, superposing a further grating on the plurality of first gratings to produce moire fringes with the replicas, adjusting the relative position of the replicas until the moire fringes indicate that the grating lines of the replicas are parallel and in phase, and bonding the replicas in this relative position.
  • each replica grating has a substrate which is shorter in length than the length of the master grating.
  • each replica grating is formed with a substrate having a grating face which is rectangular.
  • each replica grating is formed with a substrate longitudinal cross section of parallelogram form.
  • each replica grating is formed with a substrate having a longitudinal cross section of rectangular form.
  • each replica grating is formed with grating lines extending across it from side to side and two such replica gratings are clamped in a jig edge to edge in spaced relation, one of the replica gratings being clamped stationary while the other is adjustably clamped, the relative position of the gratings then being adjusted and the gratings are bonded by being cemented together.
  • the common master grating is itself a composite diffraction grating prepared from a plurality of replica gratings replicated from a common master grating.
  • replica gratings are produced from the master grating by casting a resin on the master grating, securing a substrate to the thus cast resin and removing the substrate and cast resin from the master grating after hardening of the resin.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)
US662433A 1966-08-26 1967-08-22 Method of manufacturing an elongated composite diffraction grating Expired - Lifetime US3622411A (en)

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JP5579666A JPS4527426B1 (enrdf_load_stackoverflow) 1966-08-26 1966-08-26

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4160328A (en) * 1977-06-21 1979-07-10 Dr. Johannes Heidenhain Gmbh Segmented longitudinal measuring device
FR2532966A1 (fr) * 1982-09-15 1984-03-16 Rca Corp Dispositif perfectionne d'authentification par diffraction et reflexion
WO1995030179A1 (en) * 1994-05-02 1995-11-09 Instruments Sa, Inc. A method of forming a holographic diffraction grating
US20160167309A1 (en) * 2013-07-31 2016-06-16 Panowin Technologies Co., Ltd Closed-loop control fused deposition modeling high-speed 3d printer and closed-loop control method
CN112400100A (zh) * 2018-07-02 2021-02-23 京瓷株式会社 分光器、天体望远镜以及分光器的制造方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3113347A (en) * 1962-09-12 1963-12-10 Stephen S Kufrovich Safety panel laminating apparatus
US3166624A (en) * 1961-05-05 1965-01-19 Bausch & Lomb Moire fringe device having line grids of gradually changing pitch
US3245307A (en) * 1958-01-21 1966-04-12 Philips Corp Moire fringe apparatus for measuring small movements
US3488512A (en) * 1966-12-07 1970-01-06 Contraves Ag Shutter for increasing the contrast of moire patterns
US3496364A (en) * 1968-01-23 1970-02-17 Dynamics Res Corp Linear encoder having a fringe pattern produced by optical imaging

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3245307A (en) * 1958-01-21 1966-04-12 Philips Corp Moire fringe apparatus for measuring small movements
US3166624A (en) * 1961-05-05 1965-01-19 Bausch & Lomb Moire fringe device having line grids of gradually changing pitch
US3113347A (en) * 1962-09-12 1963-12-10 Stephen S Kufrovich Safety panel laminating apparatus
US3488512A (en) * 1966-12-07 1970-01-06 Contraves Ag Shutter for increasing the contrast of moire patterns
US3496364A (en) * 1968-01-23 1970-02-17 Dynamics Res Corp Linear encoder having a fringe pattern produced by optical imaging

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4160328A (en) * 1977-06-21 1979-07-10 Dr. Johannes Heidenhain Gmbh Segmented longitudinal measuring device
FR2532966A1 (fr) * 1982-09-15 1984-03-16 Rca Corp Dispositif perfectionne d'authentification par diffraction et reflexion
WO1995030179A1 (en) * 1994-05-02 1995-11-09 Instruments Sa, Inc. A method of forming a holographic diffraction grating
US20160167309A1 (en) * 2013-07-31 2016-06-16 Panowin Technologies Co., Ltd Closed-loop control fused deposition modeling high-speed 3d printer and closed-loop control method
CN112400100A (zh) * 2018-07-02 2021-02-23 京瓷株式会社 分光器、天体望远镜以及分光器的制造方法
EP3819614A4 (en) * 2018-07-02 2022-04-13 Kyocera Corporation SPECTROSCOPE, TELESCOPE AND SPECTROSCOPE MANUFACTURING METHOD

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