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

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

Manufacturers : PixArt

Image and pinout :

Some of the text within the PDF file :

Data Sheet ADNS-3090 High-Performance Optical Mouse Sensor Description The ADNS-3090 is a high performance addition to PixArt Imaging’ 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 60 inches per second and acceleration up to 20g – for increased user precision and smoothness. The ADNS-3090 along with the ADNS-2120-001 trim lens, ADNS-2220-001 assembly clip and HLMP-EG3E-xxxxx led 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 programmed [ ... ]

ADNS-3090 PDF Datasheet Download