1. Field of the Invention
The present invention relates in general to a distance measurement using a light beam, and more particularly to an apparatus and a method for measuring a distance optically using a phase variation in which a distance to an object can be measured with no contact using a light beam, so that they are applicable to various distance measurements including a distance measurement of a car collision prevention system.
2. Description of the Prior Art
Conventional distance measurement equipments are mostly adapted to measure distances to objects relatively using standard measurement devices with corresponding lengths.
Such a conventional distance measurement equipment utilizes trigonometry to measure a distance. For this reason, the conventional distance measurement equipment needs a relative measurement device with a length corresponding to the distance to be measured, or many measurement devices to calculate the distance. As a result, the conventional distance measurement equipment is complex in construction. In particular, it is impossible to install the conventional distance measurement equipment in a car for the purpose of measuring continuously the distance in traveling of the car.
For the purpose of being installed in a desired car to measure continuously distances to the front and rear cars in the traveling, so as to prevent a car collision, distance measurement equipments using a laser beam and an ultrasonic wave have been researched and developed. However, the distance measurement equipment using the ultrasonic wave has a disadvantage in that it cannot perform a long-distance measurement due to a natural characteristic of the ultrasonic wave. Also, the distance measurement equipment using the ultrasonic wave cannot perform the distance measurement at a high speed. On the other hand, the distance measurement equipment using the laser beam may not be able to perform the distance measurement precisely.