Marine Biological Laboratory

Cambridge Research Instrumentation, Inc.

Rudolf Oldenbourg

Mykhailo Shribak

Clifford C Hoyt

Peter J Miller

Paul John Cronin

Peter Török

In an apparatus and method for measuring parameters related to retardance and slow axis azimuth in sample specimens, a sample is illuminated by circularly polarized monochromatic light which is then analyzed by an elliptical analyzer at different settings. In another embodiment, light conditioned by an elliptical polarizer at various settings illuminates a specimen and the beam exiting the sample is analyzed by a circular analyzer. Background images obtained with selected settings of the elliptical analyzer/polarizer, but without the sample present. Algorithms are described which employ two specimen images with elliptical settings and three or two background images; or which employ three specimen images with elliptical settings; or which employ four specimen images with elliptical settings without an extinction setting; or which employ five specimen images with four elliptical settings and one extinction setting. These algorithms allow one to variously optimize measurements for speed, sensitivity, and accuracy.

Retardance measurement system and method

In an apparatus and method for measuring retardance and slow axis azimuth in sample specimens, a sample is illuminated by circularly polarized monochromatic light which is then analyzed by an elliptical analyzer at different settings. In another embodiment, light conditioned by an elliptical polarizer at various settings illuminates a specimen and the beam exiting the sample is analyzed by a circular analyzer. The elliptical analyzer/polarizer may have selectable ellipticity and azimuth angle, including in some cases a setting of circular polarization. Background images obtained with selected settings of the elliptical analyzer/polarizer, but without the sample present, are used in some embodiments to improve the measurement.

The invention provides a highly sensitive measurement of retardance and slow axis orientation, accurately and instantaneously, across a full two-dimensional image. There are no moving parts and there need not be any electro-optic tuning as part of the measurement. It is ideally adapted to real-time imaging and is well-suited to use with biological and medical samples, including visualizing structures in oocytes. The invention splits a light beam into several beams, which are analyzed using elliptical polarizers and the resultant intensity is measured. It can be constructed using a single pixilated detector, or several detectors, to achieve high spatial resolution when this is desired.

Instantaneous polarization measurement system and method

A microscope system for determining optical properties of a specimen includes a source of polarized light, a detector for detecting the intensity of light incident thereon, an optical path extending from the source to the detector, a condenser for providing light from the source to the specimen, an objective for receiving light from the specimen, a support for mounting the specimen, a sectored variable retarder mounted in the optical path, and a polarized light analyzer mounted in the path between the sectored variable retarder and the detector. The variable retarder has a multiple sectors. Each sector is individually addressable by a control signal that affects the light retardation characteristics of the sector.

Enhancing polarized light microscopy

A method for measuring sample retardance in the presence of spurious background retardance contributed by optical components such as strained lenses in the measurement system, which is accurate where there is a retardance in excess of 15 degrees in the sample, the background, or the combination thereof. The method can be applied to imaging systems that record polarized light intensities for obtaining retardance magnitude and angular orientation values at all points in a scene simultaneously. The system first takes images that record the apparent slow axis orientation and the apparent retardance of the sample at all image points. Then the sample is removed and images are taken that record the background retardance alone. Algorithms for minimizing the effect of the background retardance on the measured sample retardance make use of the separately measured polarized light intensities of sample with background and of the background alone. The algorithms can be applied to each picture element simultaneously and do not make use of spatial relationships or distributions within the sample.

Growing community of inventors

Falmouth, MA, United States of America

Rudolf Oldenbourg