A compact holographic optical tweezers instrument

Abstract

Visual and dynamical measurement of Rayleigh-Benard convection by using fiber-based digital holographic interferometry J. Appl. Phys. 112, 113113 (2012) Guide-star-based computational adaptive optics for broadband interferometric tomography Appl. Phys. Lett. 101, 221117 (2012) Limits of elemental contrast by low energy electron point source holography J. Appl. Phys. 110, 094305 (2011) Cantilever biosensor reader using a common-path, holographic optical interferometer Appl. Phys. Lett. 97, 221110 (2010) Extended depth of focus in a particle field measurement using a single-shot digital hologram Appl. Phys. Lett. 95, 201103 (2009) Additional information on Rev. Sci. Instrum. Holographic optical tweezers have found many applications including the construction of complex micron-scale 3D structures and the control of tools and probes for position, force, and viscosity measurement. We have developed a compact, stable, holographic optical tweezers instrument which can be easily transported and is compatible with a wide range of microscopy techniques, making it a valuable tool for collaborative research. The instrument measures approximately 30×30×35 cm and is designed around a custom inverted microscope, incorporating a fibre laser operating at 1070 nm. We designed the control software to be easily accessible for the non-specialist, and have further improved its ease of use with a multi-touch iPad interface. A high-speed camera allows multiple trapped objects to be tracked simultaneously. We demonstrate that the compact instrument is stable to 0.5 nm for a 10 s measurement time by plotting the Allan variance of the measured position of a trapped 2 μm silica bead. We also present a range of objects that have been successfully manipulated.

A multi-modal stereo microscope based on a spatial light modulator

“…1 and 2, is similar to that of our recent work developing a compact optical tweezer system [20]. Focussing is achieved by moving the objective lens on a motorised stage (LS-50-M, ASI) which is mounted vertically within the aluminium frame of the microscope.…”

Spatial light modulation for improved microscope stereo vision and 3D tracking

“…2 and 3, is similar to the compact optical tweezer system. 20 The inverted microscope objective is focussed by a motorised stage (LS-50-M, ASI) that is mounted vertically inside an aluminium frame of the microscope. Positioning of the sample is achieved by moving a motorised X-Y stage (MS-2000, ASI).…”

Holographic tracking and sizing of optically trapped microprobes in diamond anvil cells

“…Stable 3D trapping is impossible at such a low NA when using a single trapping beam. To overcome this problem, we have modified our portable holographic optical tweezers instrument [5] (see Fig. 1(a)) to produce two counter propagating beams [12,13].…”

“…The possibility of precisely sizing a colloidal probe particle is crucial for retrieving absolute viscosity measurements from the center of mass dynamics of the probe bead [2]. Holographic optical tweezers (HOT) [3][4][5] offer a powerful tool for microrheological studies [6][7][8] and, when combined with DHM, allow for a full 3D and multipoint particle tracking for viscosity measurements [2]. The need for a high numerical aperture for stable axial trapping has confined HOT to situations where samples could be accessed using short working distance objectives.…”