Vibration visualization element including optical member

A vibration measurement system comprising:

• a first vibration visualization element and a second vibration visualization element that are fixed to a measurement object,
• a light source that emits light or electromagnetic wave to the first vibration visualization element and the second vibration visualization element, and
• an imaging device that captures an image including the measurement object, the first vibration visualization element and the second vibration visualization element, wherein
• each of the first and second vibration visualization elements comprises an optical member that retroreflects the light or the electromagnetic wave, the optical member including:
• a fixed section, relative positional relationship of which with respect to the measurement object is fixed;
• and
• a movable section movably supported by the fixed section to allow relative positional relationship with the fixed section to be changed by application of an acceleration to the fixed section in a predetermined direction, wherein
• the fixed section and the movable section are configured such that, according to the change in the relative positional relationship between the fixed section and the movable section, a reflection direction of the light or the electromagnetic wave is changed to change a luminance of reflected light in a retroreflection direction or an amount of reflected electromagnetic wave in the retroreflection direction.

A vibration measurement method using a vibration visualization element fixed to a measurement object, wherein

• the vibration visualization element retroreflects light or electromagnetic wave, and changes a reflection direction of the light or the electromagnetic wave to change a luminance of reflected light in a retroreflection direction or an amount of reflected electromagnetic wave in the retroreflection direction due to application of an acceleration to the visualization element in a predetermined direction, and
• the method comprises:
• emitting the light or the electromagnetic wave to the vibration visualization element;
• capturing an image including the measurement object and the vibration visualization element;
• and
• measuring vibration of the measurement object based on the change in a luminance of the reflected light or an amount of the reflected electromagnetic wave from the vibration visualization element in the image.