The incorporation of polarization control on the illumination beam in a laser scanning confocal microscope allows extraction of the orientational information of submicroscopic features of a sample being studied. In this paper, we present the implementation of an optical arrangement that generates homogeneous as well as non-homogeneous user define polarization profiles over the cross-sectional area of a laser beam. A confocal system is built with this optical arrangement to obtain images of the same target with different polarized illumination beams such that there is considerable reduction in the time gap between two consecutive illuminations of each location of the sample.
A polarized light scanning optical microscopy is an important imaging technique popular for its ability to determine the information on molecular orientation of the sample being studied. The determination of the molecular orientation directly depends on the electric field orientation around the focus of a lens, which is used to focus the light to illuminate the sample. In this paper, we present the effect on the electric field orientation at the focal plane of the lens due to the presence of a few primary optical aberration present in the light beam.
The high resolution applications of a laser scanning imaging system very much demand the accurate positioning of the illumination beam. The galvanometer scanner based beam scanning imaging systems, on the other hand, suffer from both short term and long term beam instability issues. Fortunately Computer generated holography based beam scanning offers extremely accurate beam steering, which can be very useful for imaging in high-resolution applications in confocal microscopy. The holographic beam scanning can be achieved by writing a sequence of holograms onto a spatial light modulator and utilizing one of the diffracted orders as the illumination beam. This paper highlights relative advantages of such a holographic beam scanning based confocal system and presents some of preliminary experimental results.
The estimation of the Point Spread Function (PSF) of an imaging system is important for various post acquisition processes. The PSF can be estimated by knowing the optical arrangement of the imaging system or can be obtained by using a point object. Both the techniques have their own limitations. In this paper we propose a new PSF estimation technique based on a target that can be reconfigured programmably. We will show that a target with different illumination areas can be imaged to establish a relation between the image plane and the object plane via a PSF. The relation thus allows one to estimate the PSF of the imaging system.
In confocal microscopy the polarization of the illumination beam plays an important role in determining the orientation of the fluorescent molecules being illuminated. The efficiency of the excitation depends on the angle between the excitation electric field and the direction of the molecular dipole. In order to determine the orientation of the fluorescent molecules in the focal plane the molecules are to be excited using two mutually orthogonal electric fields. In this paper we show how a computer generated holography technique can be implemented using a ferroelectric liquid crystal spatial light modulator to conveniently obtain two images of the same target once with an X polarized illumination beam and another with a Y polarized illumination beam.