We present an experimental demonstration of a method using optical tweezers proposed by Fischer and Berg-Sorensen
for measuring viscoelasticity using optical tweezers. It is based on a sinusoidal oscillation of the liquid in combination
with force measurements using optical tweezers. We verify the method by applying it to measurements in water, glycerol
and polyethylene oxide (PEO).
We are exploring a biological application of optical tweezers with fluorescence imaging for microrheometry.
Measurement of the power spectrum of Brownian motion of a trapped probe particle or vesicle provides information on
the viscoelastic properties of the surrounding medium which can change in response to cellular processes or the effect of
We report the observation of Mathieu-Gauss modes generated in a stable CO<sub>2</sub> laser resonator composed by an axicon
and a plane mirror. Several low order even and odd Mathieu-Gauss modes were obtained by slightly breaking the
symmetry of the cavity. Intracavity elements were used for obtaining odd Mathieu modes. The nondiffracting nature of
the Mathieu-Gauss modes is measured indirectly by recording their annular spectra at the focal plane of a converging
external lens. The experimental results are corroborated with theoretical predictions.
Proc. SPIE. 6090, Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing XIII
KEYWORDS: 3D image enhancement, 3D image reconstruction, Visualization, Image processing, Digital imaging, Image enhancement, Reconstruction algorithms, Imaging arrays, Integral imaging, 3D image processing
In this work, we are proposing the use of digital image enhancement in three dimensional (3D) Integral Imaging (InI) applying in small objects visualization. We used a well known image filter algorithm for enhance the edges and detail information of the 3D reconstruction InI image via unsharp masking. Small objects as bugs were recorded in an elemental image array, image processed and digital reconstructed as 3D objects. We implemented the algorithm over the elemental image array as usual and using an innovative technique that involves a simple digital reconstruction algorithm by quadruple pixel extraction. Digital results show an improvement in details visualization, which have potential application in 3D microscopy.
We report the generation of Bessel-Gauss beams using a CO<sub>2</sub> laser resonator. The cavity is composed by a plane output mirror and a total reflective axicon, this configuration had been studied previously by Gutierrez-Vega et al [J.Opt.Soc.Am.A <b>20</b>, 2113-22 (2003)]. Bessel-Gauss beams are produced directly from the cavity. The use of a reflective axicon instead of a refractive one results in reduction of surface-induced aberrations, minimizing absorption and increasing the non-diffracting distance. This results in a higher power non-diffracting laser beam with potential scientific and industrial applications. In order to characterize the resonator, we have obtained its output transverse intensity distribution. Additionally, we have numerically and experimentally studied the
effects of mirror tilt on the output transverse mode structure. We have made numerical simulations of the misaligned resonator modes based on Bowers’s method [Appl. Opt. <b>31</b>, 1185-98 (1992)]. Direct comparison of numerical and experimental results allow us to estimate the diffractive losses of the modes on the misaligned cavity and their dependence on the aligned bare cavity eigenmodes, thus providing valuable information of the output power dependence on mirror misalignment. Relevant experimental parameters and numerical procedure are fully described.