Shape measurement apparatus and shape measurement method

1. A shape measurement apparatus comprising:

a light source configured to irradiate a surface of a moving strip-shaped body with linear light at a prescribed angle of incidence from an upstream side or a downstream side in a movement direction of the strip-shaped body;

a screen configured such that reflected light of the linear light on the surface of the strip-shaped body is projected on the screen;

an area camera configured to image the reflected light of the linear light projected on the screen; and

a central processing unit configured to acquire surface roughness distribution of the strip-shaped body to detect minute roughness irregularity on the basis of width distribution of a light strip of the reflected light of the linear light imaged by the area camera,

wherein the prescribed angle of incidence is set in accordance with target surface roughness of the surface of the strip-shaped body, and

wherein a width of the linear light is configured to be larger than the target surface roughness of the surface of the strip-shaped body.

2. The shape measurement apparatus according to claim 1 , wherein a spectral half-width of the light source is 20 nm or more.

3. The shape measurement apparatus according to claim 1 , wherein an angle of incidence of the light source is made larger for larger target surface roughness of the surface of the strip-shaped body.

4. The shape measurement apparatus according to claim 2 , wherein an angle of incidence of the light source is made larger for larger target surface roughness of the surface of the strip-shaped body.

5. The shape measurement apparatus according to claim 1 ,

wherein the central processing unit is further configured to:

acquire, from luminance distribution of a light strip of reflected light of the strip-shaped body included in a captured image acquired by the area camera, width distribution of the light strip, and

acquire the surface roughness distribution of the strip-shaped body on the basis of the width distribution of the light strip.

6. The shape measurement apparatus according to claim 5 ,

wherein the central processing unit is further configured to:

determine whether the surface of the strip-shaped body has the target surface roughness, on the basis of the surface roughness distribution.

7. The shape measurement apparatus according to claim 2 ,

wherein the central processing unit is further configured to:

acquire, from luminance distribution of a light strip of reflected light of the strip-shaped body included in a captured image acquired by the area camera, width distribution of the light strip, and

acquire the surface roughness distribution of the strip-shaped body on the basis of the width distribution of the light strip.

8. The shape measurement apparatus according to claim 7 ,

wherein the central processing unit is further configured to:

determine whether the surface of the strip-shaped body has the target surface roughness, on the basis of the surface roughness distribution.

9. The shape measurement apparatus according to claim 3 ,

wherein the central processing unit is further configured to:

acquire, from luminance distribution of a light strip of reflected light of the strip-shaped body included in a captured image acquired by the area camera, width distribution of the light strip, and

acquire the surface roughness distribution of the strip-shaped body on the basis of the width distribution of the light strip.

10. The shape measurement apparatus according to claim 9 ,

wherein the central processing unit is further configured to:

determine whether the surface of the strip-shaped body has the target surface roughness, on the basis of the surface roughness distribution.

11. The shape measurement apparatus according to claim 4 ,

wherein the central processing unit is further configured to:

acquire, from luminance distribution of a light strip of reflected light of the strip-shaped body included in a captured image acquired by the area camera, width distribution of the light strip, and

acquire the surface roughness distribution of the strip-shaped body on the basis of the width distribution of the light strip.

12. The shape measurement apparatus according to claim 11 ,

wherein the central processing unit is further configured to:

determine whether the surface of the strip-shaped body has the target surface roughness, on the basis of the surface roughness distribution.

13. A shape measurement method comprising:

a first step of using a light source to irradiate a surface of a moving strip-shaped body with linear light diagonally from an upstream side in a movement direction of the strip-shaped body, and using an area camera to image a screen on which reflected light of the linear light on the surface of the strip-shaped body is projected and acquiring a captured image in which a screen image that is reflected light of the strip-shaped body is included, the light source being installed to have an angle of incidence set in accordance with target surface roughness of the surface of the strip-shaped body so that a width of the linear light is larger than the target surface roughness of the surface of the strip-shaped body; and

a second step of acquiring surface roughness distribution of the strip-shaped body to detect minute roughness irregularity on the basis of width distribution of a light strip of the reflected light of the linear light projected on the screen.