Abstract

A new detection method for the reference position (zero position) of an optical encoder by using a diffraction grating with variable pitch is proposed. Movement of the diffraction grating changes the position of the grating relative to the radiating laser spot, altering the grating pitch that is illuminated by the laser and causing a change in the diffraction angle of the beam. The change is detected by two photodiodes. Our experiment shows that the method can provide highly accurate detection of the reference point in the submicrometer range.

© 1993 Optical Society of America

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References

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  1. M. Kajitani, “High resolution linear scale,” J. Jpn. Soc. Prec. Eng. 57, 1943–1947 (1991).
    [CrossRef]
  2. J. Akedo, H. Kobayashi, H. Machida, “Study of laser encoder by using a point source diffraction,” J. Soc. Inst. Cont. Eng. Jpn. 25, 1148–1155 (1989).
  3. J. Akedo, H. Machida, H. Koybayashi, Y. Shirai, H. Ema, “Point source diffraction and its use in an encoder,” Appl. Opt. 27, 4777–4781 (1988).
    [CrossRef] [PubMed]
  4. S. Kataoka, Y. Shibata, K. Takahashi, H. Yamazaki, eds., Sensor Handbook (Baifukan, Tokyo, 1986), pp. 430–435.
  5. J. Akedo, R. Iino, F. Koyama, H. Kobayashi, “Formation of a diffractional grating by magnetic Iithography,” IEEE Trans. Magn. Jpn. 5, 683–689 (1990).
    [CrossRef]
  6. J. Akedo, H. Machida, H. Kobayashi, “Development of laser encoder using a point source diffraction (No. 2),” presented at the 1990 Spring Annual Meeting of the Japanese Society for Precision Engineering, Tokyo.

1991 (1)

M. Kajitani, “High resolution linear scale,” J. Jpn. Soc. Prec. Eng. 57, 1943–1947 (1991).
[CrossRef]

1990 (1)

J. Akedo, R. Iino, F. Koyama, H. Kobayashi, “Formation of a diffractional grating by magnetic Iithography,” IEEE Trans. Magn. Jpn. 5, 683–689 (1990).
[CrossRef]

1989 (1)

J. Akedo, H. Kobayashi, H. Machida, “Study of laser encoder by using a point source diffraction,” J. Soc. Inst. Cont. Eng. Jpn. 25, 1148–1155 (1989).

1988 (1)

Akedo, J.

J. Akedo, R. Iino, F. Koyama, H. Kobayashi, “Formation of a diffractional grating by magnetic Iithography,” IEEE Trans. Magn. Jpn. 5, 683–689 (1990).
[CrossRef]

J. Akedo, H. Kobayashi, H. Machida, “Study of laser encoder by using a point source diffraction,” J. Soc. Inst. Cont. Eng. Jpn. 25, 1148–1155 (1989).

J. Akedo, H. Machida, H. Koybayashi, Y. Shirai, H. Ema, “Point source diffraction and its use in an encoder,” Appl. Opt. 27, 4777–4781 (1988).
[CrossRef] [PubMed]

J. Akedo, H. Machida, H. Kobayashi, “Development of laser encoder using a point source diffraction (No. 2),” presented at the 1990 Spring Annual Meeting of the Japanese Society for Precision Engineering, Tokyo.

Ema, H.

Iino, R.

J. Akedo, R. Iino, F. Koyama, H. Kobayashi, “Formation of a diffractional grating by magnetic Iithography,” IEEE Trans. Magn. Jpn. 5, 683–689 (1990).
[CrossRef]

Kajitani, M.

M. Kajitani, “High resolution linear scale,” J. Jpn. Soc. Prec. Eng. 57, 1943–1947 (1991).
[CrossRef]

Kobayashi, H.

J. Akedo, R. Iino, F. Koyama, H. Kobayashi, “Formation of a diffractional grating by magnetic Iithography,” IEEE Trans. Magn. Jpn. 5, 683–689 (1990).
[CrossRef]

J. Akedo, H. Kobayashi, H. Machida, “Study of laser encoder by using a point source diffraction,” J. Soc. Inst. Cont. Eng. Jpn. 25, 1148–1155 (1989).

J. Akedo, H. Machida, H. Kobayashi, “Development of laser encoder using a point source diffraction (No. 2),” presented at the 1990 Spring Annual Meeting of the Japanese Society for Precision Engineering, Tokyo.

Koyama, F.

J. Akedo, R. Iino, F. Koyama, H. Kobayashi, “Formation of a diffractional grating by magnetic Iithography,” IEEE Trans. Magn. Jpn. 5, 683–689 (1990).
[CrossRef]

Koybayashi, H.

Machida, H.

J. Akedo, H. Kobayashi, H. Machida, “Study of laser encoder by using a point source diffraction,” J. Soc. Inst. Cont. Eng. Jpn. 25, 1148–1155 (1989).

J. Akedo, H. Machida, H. Koybayashi, Y. Shirai, H. Ema, “Point source diffraction and its use in an encoder,” Appl. Opt. 27, 4777–4781 (1988).
[CrossRef] [PubMed]

J. Akedo, H. Machida, H. Kobayashi, “Development of laser encoder using a point source diffraction (No. 2),” presented at the 1990 Spring Annual Meeting of the Japanese Society for Precision Engineering, Tokyo.

Shirai, Y.

Appl. Opt. (1)

IEEE Trans. Magn. Jpn. (1)

J. Akedo, R. Iino, F. Koyama, H. Kobayashi, “Formation of a diffractional grating by magnetic Iithography,” IEEE Trans. Magn. Jpn. 5, 683–689 (1990).
[CrossRef]

J. Jpn. Soc. Prec. Eng. (1)

M. Kajitani, “High resolution linear scale,” J. Jpn. Soc. Prec. Eng. 57, 1943–1947 (1991).
[CrossRef]

J. Soc. Inst. Cont. Eng. Jpn. (1)

J. Akedo, H. Kobayashi, H. Machida, “Study of laser encoder by using a point source diffraction,” J. Soc. Inst. Cont. Eng. Jpn. 25, 1148–1155 (1989).

Other (2)

S. Kataoka, Y. Shibata, K. Takahashi, H. Yamazaki, eds., Sensor Handbook (Baifukan, Tokyo, 1986), pp. 430–435.

J. Akedo, H. Machida, H. Kobayashi, “Development of laser encoder using a point source diffraction (No. 2),” presented at the 1990 Spring Annual Meeting of the Japanese Society for Precision Engineering, Tokyo.

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Figures (9)

Fig. 1
Fig. 1

Schematic of the conventional method that detects the light intensity that passes through a slit from a small focused light spot.

Fig. 2
Fig. 2

Schematic of the conventional method that uses two half-knife-edges.

Fig. 3
Fig. 3

Principle of Z-phase signal detection.

Fig. 4
Fig. 4

Method to get 1 edge Z-phase signal at a rotary encoder.

Fig. 5
Fig. 5

(a) Procedure used for making a grating, (b) Fraunhofer diffraction images of each grating pitch in diffraction grating G1 for Z-phase detection.

Fig. 6
Fig. 6

Microphotograph of grating G1 showing a stepwise change in pitch of the grating.

Fig. 7
Fig. 7

(a) Experimental setup, (b) Relationship between lateral displacement and photodetector (PD3) output (X-axis input).

Fig. 8
Fig. 8

(a) Relationship between the movement of a stepwise grating (G1) and the intensity of primary diffraction beams, (b) Comparator output obtained by using an X–Y recorder, (c) Comparator output obtained by using a storage scope.

Fig. 9
Fig. 9

Relationship between the light source intensity and fluctuation of the reference position.

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