1.   The two problems are uneven illumination of the map and geometrical distortion introduced by the optical system.

2.   Three types of optical system are available, schlieren, interference, and UV absorption.

3.   Again there are various optical systems.

4.   The advantage over direct interferometry is that the demands on the quality of the optical system are less severe.

5.   Turbulence in lasers and other optical systems is a newly recognised rather than new phenomenon.

6.   And if the driver does take over, the optical system is automatically overridden.

7.   Another optical system, called a solar pump, will convert the light into a powerful laser beam.

8.   Because infrared light does not travel through walls as radio waves do, a wireless optical system in one room does not interfere with one in another room.

9.   Blacks were more likely than whites to live in districts that vote with old punch-card machines instead of the more modern and reliable optical scanning system.

10.   But the Veridicom chip, which was developed by scientists at Bell Labs, is smaller and cheaper than optical systems.