Optical micro encoder using a vertical-cavity surface-emitting laser

Performance of an optical encoder based on a nondiffractive beam implemented with a specific photodetection integrated circuit and a diffractive optical element

“…Optical encoders are rotation or linear displacement sensors that reach submicrometric resolution and are used in a wide variety of equipment such as printers, lathes, radars, robots, satellites, etc. There are several optical encoder designs, but all of them rely on the movement of an optical head with respect to a fixed scale [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The optical head includes one or more light sources that shed some kind of structured light beam, which is shaped by the scale.…”

“…However, steel tape gratings are used for measuring displacements longer than 3 m. The influence of the steel roughness on the encoder performance for the aforementioned grating configurations has been studied [6]. Besides these common optical encoders, there are others based on interferential diffractive [7][8][9] and alternative [10][11][12][13] designs.…”

Miniature Reflection-Type Optical Displacement Sensor Incorporating a Projected Beam

“…The photonic sensor, which involves a code scale, a light source, a receiver based on photodetectors (PDs), and a signal processing circuit, is preferably required to satisfy compact size and low cost [1], [2], [10]- [12]. Depending on the arrangement of the constituent components, the sensor is classified into reflection [1]- [7] or transmission [13]- [17] types. Previously, compact reflectiontype sensors resorting to an index grating structure in combination with a beam shaper were reported, drawing upon a collimated beam [4].…”