JPH0319528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a slit light source used as a structural illumination device in three-dimensional measurement, distance image generation, etc. using a light cutting method.

[Prior art]

FIG. 2 is a diagram for explaining a first conventional slit light source.

In Fig. 2, 1 is a high-intensity lamp, 2 is a slit plate having a slit 2a in the center, and 3 is a lens for converting the slit light obtained by the slit plate 2 into a slit light 3 having a predetermined length l. be.

Note that the high-intensity lamp 1, slit plate 2, and lens 3 are arranged so that their respective centers coincide with the Z-axis direction.

FIG. 3 is a diagram for explaining a second conventional slit light source.

In FIG. 3, 4 is a laser diode, 5 is a collimating lens for converting the diverging light emitted from the laser diode 4 into circular parallel light, and 6
is a cylindrical lens for converting the parallel light made parallel by the collimating lens 5 into an elongated elliptical spot light 6a.

In addition, as in FIG. 2, the center of each member is Z.
It is arranged to match the axial direction.

[Problem that the invention seeks to solve]

Generally, in three-dimensional measurement and distance image generation using the optical cutting method, a slit light beam of sufficient length to traverse the screen is required.

However, in the conventional slit light source explained using FIGS. 2 and 3, the lens 3,
Since the length of the slit light is determined by the focal length of the cylindrical lens 6, in order to obtain a sufficiently long slit light, a lens system with a short focal length must be constructed, which reduces the cost of the device. There was a problem that caused the price to rise significantly.

In addition, the slit light emitted from a lens system with a short focal length reflects the brightness distribution of the light source directly in the slit light, so the brightness is extremely high near the optical axis, and the brightness decreases rapidly toward the periphery. There was a problem.

[Means for solving problems]

In view of the above-mentioned conventional drawbacks, the present invention provides a slit light source that can obtain a sufficiently long slit light without reducing brightness in the peripheral area with a simple and inexpensive configuration. a light emitting source that emits light of a certain wavelength; a collimating lens that converts the light from the light emitting source into parallel light; a cylindrical lens that converts the parallel light into elliptical spot light; a diffraction grating arranged in a direction perpendicular to the axial direction of the lens, and the diffraction grating receives parallel light incident on the cylindrical lens;
Alternatively, the slit light source is provided to diffract an elliptical spot light emitted from the lens.

[Effect]

In other words, the above-mentioned slit light source converts light of a single wavelength emitted from the light emitting source (otherwise, interference fringes will not occur due to the diffraction grating, and it does not necessarily have to be uniform) to be diffracted using a plurality of gratings. Taking advantage of the fact that when a grating is irradiated, the light diffracted by each grating interferes and is obtained as multiple spot lights on a straight line on the image plane, the light irradiated onto the diffraction grating is shaped into an elliptical shape by a cylindrical lens. spot light, pass it through a diffraction grating, and then overlap the tips of the plurality of obtained elliptical spot lights (the degree of overlap is set by appropriately setting the focal length of the cylindrical lens). As a result, one long slit of light is obtained as a whole.

In addition, after converting parallel light into multiple spot lights,
Each spot light may be made into an elliptical shape by a cylindrical lens and then formed into a single slit light.

〔Example〕

FIG. 1 is a diagram for explaining an embodiment of a slit light source according to the present invention.

In the figure, 7 is a laser diode (a light emitting diode may be used) that emits light of a single wavelength, 8 is a collimating lens that converts the diverging light of a single wavelength from the laser diode 7 into parallel light, and 9 is an elongated ellipse that converts the parallel light. A cylindrical lens converts the spot light _9a into a spot light 9a, and 10 is a plurality of optical fibers 10 to 1.
0 _-o is a fiber array arranged one-dimensionally in the y direction and constitutes a diffraction grating. Each member is arranged so that its center coincides with the Z-axis direction. The arrangement direction of each optical fiber in the fiber array 10 is a direction perpendicular to the axial direction of the cylindrical lens 9 (x direction in the figure).

As the fiber array 10, there is a fiber grating (trade name: Machida Seisakusho).

Further, the fiber array 10 is arranged at any position other than the focal length f of the cylindrical lens 9 such that the elliptical spot light _9a is irradiated onto each of the fibers _10-1 to 10 _-o .

In the configuration described above, the single wavelength light from the laser diode 7 is converted into parallel light by the collimating lens 8 and then enters the cylindrical lens 9. The cylindrical lens 9 into which the parallel light is incident is parallel in the x-axis direction (same width) and forms an elongated elliptical spot light 9 _a extending only in the y-axis direction, and makes it incident on the fiber array 10 . As mentioned above, the fiber array 10
is provided so that the arrangement direction of each fiber 10 _-1 to 10 _-o is perpendicular to the axial direction (x direction) of the cylindrical lens 9, so that the length direction (y direction) of the spot light _9a is aligned with each fiber. 10 _-1 to 10 _-o and become a plurality of straight spot lights 9 ₁ to 9 _a in the y-axis direction, and an elongated slit light 10 _a
can be obtained.

Furthermore, by adjusting the degree of overlap (area) of the slit lights _10a in the y-axis direction, the slit lights _10a can have uniform brightness in the length direction. In addition, in the embodiment, the fiber array 1
0, but a diffraction grating in which a plurality of slits (gratings) are formed on a single plate may also be used.

In the embodiment described above, the fiber array 10 is arranged after the cylindrical lens 9, but the same slit light can be obtained even if the arrangement is reversed. However, if the distance between the two is increased, the top and bottom of the slit will be the cylindrical lens 9.
Since the parts will break depending on the size of the parts, it is necessary to place them sufficiently close to each other.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to generate slit light having a sufficient length without being out of focus in the depth direction with a very simple and inexpensive configuration.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining an embodiment of a slit light source according to the present invention, and FIGS. 2 and 3 are diagrams for explaining a conventional slit light source. In the figure, 7 is a laser diode, 8 is a collimating lens, 9 is a cylindrical lens, 9 _a ,
9 ₁ to 9 _o are spot lights, 10 is a fiber array,
_10a is a slit light.

Claims (1)

[Claims] 1. A light emitting source that emits light of a single wavelength, a collimating lens that converts the light from the light source into parallel light, a cylindrical lens that converts the parallel light into elliptical spot light, and an array of multiple gratings. A diffraction grating whose direction is perpendicular to the axial direction of the cylindrical lens, and the diffraction grating receives parallel light incident on the cylindrical lens or elliptical spot light emitted from the lens. A slit light source characterized in that it is provided to diffract light.