Precision Angle Measurement on Rough Surfaces

・Issues

Is there a method to measure the angle of a rough, machined surface—not a mirror-like surface—using a laser autocollimator?

・Solutions

On unpolished metal surfaces, laser light is usually scattered, making accurate measurement with a laser autocollimator difficult. However, by applying a thin, lightweight glass plate, such as a cover glass, onto the metal surface with one side coated with water or oil—a technique known as “wetting”—an optically flat measurement surface can be formed, allowing measurement with a laser autocollimator.