Integrated micro-displacement sensor that measures tilting angle and linear movement of an external mirror

An integrated optical micro-displacement sensor was developed that uses the beam diverging from a vertical cavity surface emitting laser (VCSEL). The sensor consists of a VCSEL (1.5 mm x 1.5 mm x 1.2 mm) that is surrounded by three photodiodes and can measure the linear distance traveled and the tilting angle of an external mirror. The resolution is 20 nm for a measurement range up to 0.4 mm, or less than 40 mn for a wider measurement range of 1.8 mm. The full range of the measurable tilting angle is 5 degrees. This sensor can be incorporated into devices with micro-mirrors, such as integrated scanning microscopes. (C) 2007 Elsevier B.V. All rights reserved.