JPS61121024A - Hologram scanner - Google Patents

Abstract

PURPOSE:To make a hologram scanner small-sized by adding the refocused light condensing function of a holotop to a conventional bottom slope to use the side face also. CONSTITUTION:Though holograms 22 and 23 are provided on lower faces of a top type rotating body holotop 20 and a reflective Fresnel lens 24 is provided on the inside upper face similarly to a conventional example, holograms 25 and 26 are formed on side faces of the holotop to give the refocused light condensing function. A refocused light 30 is diffracted by holograms 22 and 23 and is condensed onto a photodetector 28 by the reflective Fresnel lens 24 and a concave lens 27. A refocused light 21 returned to side faces of the holotop is diffracted and condensed by holograms 25 and 26 provided on side faces of the holotop and is condensed on the photodetector 28 through the concave lens 27.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hologram scanner that performs optical scanning using a hologram.

Recently, in order to save labor at registers in supermarkets and the like, barcode reading devices that read barcodes printed on the exterior of products and input them into computers have come into use.

A hologram scanner using a hologram is suitable for the optical scanning section of this barcode reading device, and therefore, this hologram scanner is often used. Such hologram scanners are required to be miniaturized and modularized to facilitate manufacturing.

[Conventional technology]

FIG. 4 is a sectional view of a main part of a conventional hologram scanner. A hologram 2.3 is provided on the bottom slope of a hollow spinning top-shaped rotating body 1, and a reflective Fresnel lens 4 is provided on the internal upper surface to form a hologram rotating body (hereinafter referred to as "holotop") 5. This holotop 5 is connected to a motor. 6, a laser beam 7 enters through a slit 9 via a mirror 8, is alternately diffracted by a hologram 2.3, and is emitted as a scanning beam 10. Re-imaging light (scattered signal light) 11 from the barcode enters the holograms 2 and 3 and is diffracted, and then is focused by a reflective Fresnel lens 4 onto a photodetector 12, where the barcode is read.

[Problem that the invention seeks to solve]

With the above configuration, it is necessary to reliably read the very weak signal light from the bar code and - code, but in order to obtain the necessary amount of light, the focusing area of the hologram 2゜3 must be reduced to the minimum necessary. It is necessary to secure it.

For this reason, a problem arises in that it is difficult to downsize the holotop in response to the demand for downsizing of hologram scanners.

[Means for solving problems]

The present invention provides a hologram scanner that solves the above-mentioned problems, and the present invention provides a hologram scanner including a hologram having a hologram for scanning and condensing a laser beam on the bottom slope of a top-shaped rotating body. This is achieved by a hologram scanner characterized in that the side surface of the image forming apparatus also has a condensing function for re-imaging light.

[For production]

Since the hologram scanner has a re-imaging light focusing function on the bottom and side surfaces of the holotop, its light focusing area is expanded compared to the conventional case where only the bottom surface is opened. Therefore, it is possible to downsize the holotop.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a main part of an embodiment of the present invention as a sectional view.

In the same figure, 2o is a holotop, 21 is a rotation axis, and 22
．． 23 is a hologram, 24 is a reflective Fresnel lens, 2
5.26 is a hologram on the side surface of the holotop, 27 is a concave lens, 28 is a photodetector, 29 is a scanning light, and 30.31 is a reimaging light.

In this embodiment, as shown in the figure, the holotop 2 is a top-shaped rotating body.
Similar to the conventional example shown in FIG. 4, holograms 22 and 23 are provided on the lower surface of the lens 0, and a reflective Fresnel lens 24 is provided on the inner upper surface. The key point of this embodiment is that holograms 25 and 26 are formed on the side surface of the holotop to provide a focusing function for re-imaging light.

In this embodiment configured in this way, as shown in FIG.
The light is focused on. Further, the re-imaging light 31 returning directly to the holotop side is diffracted and focused by holograms 25 and 26 provided on the side of the holotop, passes through a concave lens 27, and is focused on a photodetector 28.

As described above, according to this embodiment, by using the side surface of the holotop, which has not been particularly used in the past, for condensing re-imaging light, the light condensing efficiency is increased, and therefore the holotop can be made smaller. Become.

Next, a method for creating a hologram of the above-mentioned holotop will be explained with reference to FIG. First, mask the side of the holo top as shown in figure a.
0, and using an object beam 41 consisting of a diverging spherical wave and a reference beam 42 consisting of a parallel wave, the hologram 2 is
2 is created, and a hologram 23 is also created in the same way. Next, as shown in figure b (cover the hologram 22 with a mask 43, use the same object beam 41 of a diverging spherical wave as in figure a and the reference beam 44 of a convergent spherical wave, create a hologram 25 by their interference, and do the same. In this way, holograms 22, 23 and 25, 26 can also be created. Also, without using a mask, the three beams of object beam 41 and reference beam 42, 44 can be applied to the holotop at once. It can also be created by applying.

The shape of the holotop of the present invention includes a cylindrical shape as shown in FIG. 3a and a quadrangular prism shape as shown in FIG. 3S. It is easier to create a square hologram than a cylindrical hologram, but
A cylindrical shape is more suitable for rotating the holotop.

〔Effect of the invention〕

As explained above, according to the present invention, the re-imaging light focusing function of the holotop can be expanded by using the side surface in addition to the conventional bottom slope, thereby increasing the light focusing area compared to the conventional method. This makes it possible to miniaturize the holotop and realize miniaturization of the hologram scanner.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a sectional view of essential parts showing an embodiment of the hologram scanner of the present invention, Fig. 2 is a diagram for explaining the hologram creation method, and Fig. 3 is a hologram scanner of the present invention. FIG. 4 is a sectional view of a main part for explaining a conventional hologram scanner. In the figure, 20 is a holotop, 22, 23, 25, and 26 are holograms, 24 is a reflective Fresnel lens, 27 is a concave lens, 28 is a photodetector, 29 is a scanning light, and 30.31 is a reimaging light. .

Claims (1)

[Claims] 1. A hologram scanner equipped with a holotop having a hologram for laser beam scanning and condensing on the bottom slope of a top-shaped rotating body, characterized in that the side surface of the holotop also has a condensing function for reimaging light. A hologram scanner.