Pattern recognizing optical apparatus

• US 3,905,019 A
• Filed: 11/01/1973
• Issued: 09/09/1975
• Est. Priority Date: 11/02/1972
• Status: Expired due to Term

• Current Assignee: Harumi Aoki, Harumi Kawasaki, Masahide Inoue
• Original Assignee: Harumi Aoki, Harumi Kawasaki, Masahide Inoue
• Inventors: Aoki, Harumi, Inoue, Masahide, Kawasaki, Harumi
• Primary Examiner(s): Thesz, Jr., Joseph M.
• Application Number:
  US05/411,673
• Time in Patent Office: 677 Days
• Field of Search: 340/146.3P
• US Class Current: 382/210
• CPC Class Codes: G02B 27/46 Systems using spatial filters
• CPC Class Codes: G06V 10/88 Image or video recognition using optical means, e.g. reference filters, holographic masks, frequency domain filters or spatial domain filters

Abstract

A pattern recognizing apparatus having a spatial filter manufactured by exposing a surface of a hologram dry plate to a pair of light beams simultaneously directed to a point on the hologram dry plate surface with one of the light beams extending along an optical axis which is perpendicular to the surface while the other of the light beams makes a predetermined angle with respect to the optical axis. These light beams are directed through a mask which contacts the dry plate surface during exposure thereof to the light beams, this mask having a transmission function which will determine the function of the spatial filter formed by the hologram after it is developed subsequent to exposure thereof. A series of these masks which are respectively of different transmission functions are sequentially used during sequential exposures to the light beams where the light beam which makes an angle with the optical axis has different angles for the different exposures, so that in this way a multiple-point hologram is achieved. This spatial filter is then used in an optical reader where a photoelectric detecting structure is arranged along each of the axes along which the light beams which make an angle with the optical axis were directed during exposure of the dry plate.

Claims

1. In an optical reader, optical means for directing light through an input pattern extending across an optical axis of said optical means and for providing an input pattern spectrum of the input pattern at a given plane, spatial filter means situated at said plane for providing a diffraction image corresponding to the input pattern, said spatial filter means being in the form of a hologram which has been exposed at a point which receives the input pattern spectrum to a pair of intersecting light beams one of which extends along the optical axis and the other of which is at a predetermined angle with respect to said axis with the light beams passing through a mask contacting the surface of the hologram prior to development thereof and having a transmission function which determines the transmission function of the spatial filter means formed by the hologram, and photosensitive detecting means situated at the side of said spatial filter means opposite from said optical means along an axis extending at said predetermined angle through the point of the hologram exposed to said light beams for responding to the diffraction image to provide a signal capable of identifying the input pattern, said hologram which forms the spatial filter means having been exposed at said point sequentially not only to a light beam extending along the optical axis but also to a plurality of light beams respectively extending at different angles with different masks being used to provide different transmission functions so that the spatial filter means has a plurality of different transmission functions respectively extending along a plurality of axes corresponding to the angles of the light beams which extend across the optical axis at a point of the hologram which is exposed prior to development thereof, and a plurality of said photosensitive means respectiveLy situated along said axes at said different angles for responding to diffraction images extending along said axes to identify the input pattern.

2. The combination of claim 1 and wherein the spatial filter means has a plurality of points where the hologram forming the spatial filter means has been preliminarily exposed to light beams at different angles and masks with different transmission functions, a plurality of said photosensitive means being situated along of the axes corresponding to the light beams which extend at an angle to the optical axis at the several points for detecting a plurality of diffraction images and responding thereto to identify a pattern, and said optical means including means situated along the optical axis for dividing the input pattern into a plurality of elements to achieve multiple images directed to the several points of the hologram.

3. The combination of claim 2 and wherein said means for dividing the input pattern includes a plurality of microlenses.

4. The combination of claim 3 and wherein a plurality of the means for dividing the image up into elements are situated along the optical axis with lenses situated therebetween and with the last two of the means for dividing up the image which are situated before the spatial filter means defining a space along the optical axis between themselves, and a mask situated in said space for forming images of the input pattern.

5. The combination of claim 4 and wherein each of said plurality of means for dividing the image up into elements is in the form of a plurality of microlenses situated in side-by-side relation in a common plane.

6. The combination of claim 1 and wherein said spatial filter means carries out an orthogonal transformation processing of the input pattern.

7. The combination of claim 1 and wherein said spatial filter means is in the form of a hologram initially exposed to light which travels through a diffuser along the optical axis.