This multi-touch interface displays microscope video images in real-time and allows the users to intuitively trap and control objects within the microscope using optical traps.
Optical tweezers are a micromanipulation technology in which the gradient forces associated with tightly focussed laser light are exploited to exert forces on dielectric particles. By using a high numerical aperture objective lens, a laser beam is brought to a focus in a liquid sample chamber, forming a trap for micron-sized particles (see image below). These traps make an ideal environment for the investigation of systems such as dielectric colloidal particles and single cells.
Multiple optical traps can be generated and controlled by imposing a diffractive optical element (DOE) in a plane optically conjugate with the back-aperture of the objective lens. We use liquid crystal spatial light modulators (LCSLMs) for this purpose, with a 'gratings and lenses' algorithm running on a graphics card generating the necessary patterns to produce arbitrary arrays of laser focii in the microscope's image plane.