This part is a kind of semiconductor called ADNS-3090.

Function of this product has High-Performance Optical Mouse Sensor.

Manufacturers : Avago

Image and pinout :

Some of the text within the PDF file :

ADNS-3090 High-Performance Optical Mouse Sensor Data Sheet Description The ADNS-3090 is a high performance addition to Avago Technologies’ popular ADNS family of optical mouse sensors. The ADNS-3090 is based on a new, faster architecture with improved navigation. The sensor is capable of sensing high speed mouse motion - up to 6 0 inches per second and acceleration up to 2 0g – for increased user precision and smoothness. The ADNS-3090 along with the ADNS-2120-001 trim lens, ADNS-2220-001 assembly clip and HLMP-ED80-XX000 form a complete, compact optical mouse tracking system. There are no moving parts, which means high reliability and less maintenance for the end user. In addition, precision optical alignment is not required, facilitating high volume assembly. The sensor is programm [ ... ]

ADNS-3090 PDF Datasheet Download