What type of handheld tachometer requires reflective strips for operation?

A photo tachometer operates by detecting the reflection of light off a surface or a reflective strip. This type of tachometer utilizes a light source and a sensor; when the reflective strip passes by the sensor, it reflects the light back, allowing the tachometer to calculate the rotational speed of the object being measured. The requirement for reflective strips is crucial for the photo tachometer's functionality, as it relies on this reflective characteristic to accurately capture the speed of rotation.

In contrast, other types of tachometers, such as digital, mechanical, and inductive tachometers, measure speed through different means that do not necessitate the use of reflective surfaces. Digital tachometers may use internal sensors or electronic signals, mechanical tachometers often operate via direct physical connection or gear mechanisms, and inductive tachometers typically measure changes in inductance without needing reflective materials. Therefore, the use of reflective strips is specifically a characteristic feature of photo tachometers.