Abstract: A drift-adjusted interferometer and optical trap are disclosed that employ two reference beams with an optical property that allows them to be separated from the two trapping beams. The reference and trapping beams are combined collinearly and optically inverted so that each reference beam overlays with the opposite trapping beam. Each pair of beams is then focused on a microsphere and the resulting four back-focal plane interferometry signals are monitored such that the relative motion between a given trapping beam with its overlaid reference beam provides a direct measurement of the physical drift occurring due to mechanical drift of the differential path components.

Abstract: A drift-adjusted interferometer and optical trap are disclosed that employ two reference beams with an optical property that allows them to be separated from the two trapping beams. The reference and trapping beams are combined collinearly and optically inverted so that each reference beam overlays with the opposite trapping beam. Each pair of beams is then focused on a microsphere and the resulting four back-focal plane interferometry signals are monitored such that the relative motion between a given trapping beam with its overlaid reference beam provides a direct measurement of the physical drift occurring due to mechanical drift of the differential path components.

Abstract: An optical trap (and alignment device) having a light source for generating first and second light beams, and a pair of lenses for focusing the light beams to a trap region in a counter-propagating manner for trapping a particle in the trap region. A light source illuminates the trap region with a third beam of light, and a camera is positioned for capturing a portion of each of the first, second and third light beams. Actuators exert forces on generally rigid portions of optical fiber used to deliver the first and second light beams to the trap region, such that the generally rigid portions pivot about pivot points located at supported members from which the optical fibers extend. Position sensitive detectors measure the position of the beams leaving the optical fibers, and feed position signals back to the actuator drivers to ensure proper positioning of the beams.

Abstract: An alignment device and method for delivering a light beam to an optical application, such as an optical trap having a pair of lenses with overlapping focal regions for trapping a particle therein. The alignment device includes a light source for generating a beam of light, a support member, an optical fiber, a collimating lens, and actuators. The optical fiber includes an input end for receiving the beam of light, and a generally rigid portion extending from the support member and terminating in a delivery end for emitting the beam of light. The collimating lens collimates the emitted beam of light. The actuators exert forces on the generally rigid portion such that it pivots about a pivot point of the optical fiber at the support member. The collimated beam of light pivots about an optical pivot point as the optical fiber pivots about the pivot point.

Abstract: An optical trap and method for measuring both transverse and longitudinal forces on a trapped particle. Laser light sources generate first and second light beams that are focused to the trap region in a counter-propagating manner for trapping the particle. Detectors measure changes in power deflections of the light beams leaving the trap region, and changes in power concentrations of the light beams leaving the trap region. A processor calculates the transverse forces on the particle based upon the measured changes in the power deflections of the light beams, and calculates the longitudinal forces on the particle based upon the measured changes in the power concentrations of the light beams. A single beam optical trap and method are also disclosed, where the second optical beam is generated by a reflection of the first optical beam off of the trapped particle.