DISTANCE SENSOR, ALIGNMENT SYSTEM AND METHOD
FIG5B schematically illustrates a fourth embodiment of an alignment system including an approach stage
FIG5B schematically illustrates a fourth embodiment of an alignment system 100 comprising an approach stage 160 configured to position the first object 101 with respect to the second object 102. In one embodiment, a plurality of object stage actuators 121a,121b are disposed between the object stage 111a, 111b and the approach stage 160.
embodiment
160
approach stage
100
alignment system
180
controller
102
second object
101
object objects
['1. A distance sensor (1) for estimating a distance to a surface (Os) of an object (O), the distance sensor including a micro electric mechanical system , MEMS, (5) comprising a MEMS device (10) having a surface (12), denoted as MEMS sensor surface, to be arranged opposite the surface (Os) of said object (O) and a MEMS driver (20) for generating an ac driving signal to cause the MEMS sensor surface to vibrate,  characterized in that  it comprises a detection means (30) to determine a value of a property of a dynamic behavior of the MEMS (5) and a processing device (40) to estimate an average distance (h) from a measurement of the dampening of the MEMS sensor surface, as a measured distance (D 2 ) between the MEMS sensor surface (12) and the surface (O s ) of the object (O) based on the determined value for said property.', '7. An alignment system (100) for positioning and/or keeping a first object (101) at a controlled distance (D1) with respect to a second object (102), the alignment system (100) comprising a distance sensor (1) according to one of the previous claims and further comprising an object stage (111) configured to hold the first object (101) or the second (102) object, wherein a surface (101a) of the first object (101) is at a distance (D1) over a surface (102a) of the second object (102); an object stage actuator (121) configured to actuate the object stage (111) to vary the distance (D1) between the surfaces (101a, 102a) of the first and second objects (101,102); a controller (180) configured to control the object stage actuator (121) as a function of the estimated average distance (h) indicated by said distance sensor to position and/or keep the first object (101) at the controlled distance (D1) with respect to a second object (102).', '12. The alignment system according to any of the claims 7-11, comprising an approach stage (160) configured to position the first object (101) with respect to the second object (102), wherein a plurality of object stage actuators (121a,121b) are disposed between the object stage (111) and the approach stage (160).']