Optical mouse using VCSELs
View Patent ↗An optical mouse for controlling a cursor on a display. The mouse emits a light beam that interacts with a target surface and receives reflected light therefrom to detect movement of the mouse. The mouse includes a housing, a single-mode VCSEL disposed within the housing for emitting the light beam through a surface of the housing, the emitted light interacting with the target surface, a photodetector disposed within the housing that receives the light reflected from the target surface and that provides an electrical output and a processor that receives the electrical output and calculates a value that is indicative of the amount and direction of movement of the optical mouse relative to the target surface.
1. An optical mouse that interacts with a control surface to detect movement comprising:
a housing;
a single-mode VCSEL disposed within said housing that emits light through a bottom surface of the housing, the emitted light interacting with a set of reference features of the control surface that reflect and modulate the emitted light; and
a first photodetector disposed within the housing proximate the VCSEL that receives the modulated light reflected from the control surface; and
a second photodetector disposed within the housing proximate the VCSEL and offset laterally from the first photodetector by a distance equal to an integer multiple of one-fourth of a distance between respective reference features of the control surface, said first and second photodetectors providing an electrical output that is indicative of the amount and direction of movement of the optical mouse relative to the control surface.
2. The optical mouse as in claim 1 wherein the single-mode VCSEL further comprises a substrate with top and bottom surfaces, a first stack of mirror layers of alternating indices of refraction located upon the top surface of the substrate, an active layer disposed over the first stack and a second stack of mirror layers of alternating indices of refraction disposed over the active layer, said second stack of mirror layers having a first diameter adjacent the active layer and a step change to a second reduced diameter on a distal end.
3. The surface emitting laser as in claim 2 further comprising an annular contact disposed around the second stack of mirror layers on a surface of the step change from the first diameter to the second diameter.
4. The surface emitting laser as in claim 2 wherein mirror layers within the second reduced diameter further comprises an undoped distributed Bragg reflector.
5. The surface emitting laser as in claim 2 wherein mirror layers within the second reduced diameter further comprises a dielectric distributed Bragg reflector.
6. The surface emitting laser as in claim 2 wherein the second reduced diameter further comprises 4 to 5 micrometers.
7. The surface emitting laser as in claim 2 wherein the mirror layers within the second reduced diameter further comprises a height of approximately 0.2 to 1.5 micrometers.
8. An optical mouse that interacts with a control surface to detect movement comprising:
a housing;
an array having a single-mode VCSEL disposed within said housing where said VCSEL emits light through a bottom surface of the housing, the emitted light interacting with a set of reference features of the control surface that reflect and modulate the emitted light; and
first and second photodetectors of the array proximate the VCSEL that receive the modulated light reflected from the control surface, the second photodetector offset laterally from the first photodetector by a distance equal to an integer multiple of one-fourth of a distance between respective reference features of the control surface, said first and second photodetectors providing an electrical output that is indicative of the amount and direction of movement of the optical mouse relative to the control surface.
9. The optical mouse as in claim 8 further comprising a processor that determines a distance and direction of movement of the mouse from the electrical outputs of the first and second photodetectors.