Detection of targets can be difficult using thermal camera during thermal cross-over periods. Under these conditions, the target takes on the apparent temperature of objects in the foreground or background and becomes undetectable. It is commonly said that the thermal imagery is “washed-out”. When the thermal contrast of an object against its background is zero, many times a polarization contrast of the same object is non-zero. In this paper, we introduce a camera that measures thermal and polarization images in both the mid-wave infrared (MWIR) and long-wave infrared (LWIR). We also show example images and derive a simple equation that explains the conditions under which a polarization signature of an object can be expected.
A full sky imaging spectro-polarimeter has been developed that measures spectrally resolved (~2.5 nm resolution) radiance and polarization (𝑠0, 𝑠1, 𝑠2 Stokes Elements) of natural sky down-welling over approximately 2π sr between 400nm and 1000nm. The sensor is based on a scanning push broom hyperspectral imager configured with a continuously rotating polarizer (sequential measurement in time polarimeter). Sensor control and processing software (based on Polaris Sensor Technologies Grave’ camera control software) has a straight-forward and intuitive user interface that provides real-time updated sky down-welling spectral radiance/polarization maps and statistical analysis tools.
There is a strong need for the ability to terrestrially image resident space objects (RSOs) and other low earth orbit (LEO)
objects for Space Situational Awareness (SSA) applications. The Synthetic Aperture Imaging Polarimeter (SAIP)
investigates an alternative means for imaging an object in LEO illuminated by laser radiation. A prototype array
consisting of 36 division of amplitude polarimeters was built and tested. The design, assembly procedure, calibration
data and test results are presented. All 36 polarimeters were calibrated to a high degree of accuracy. Pupil plane
imaging tests were performed in by using cross-correlation image reconstruction algorithm to determine the prototype
Imaging polarimetry can be used to accurately measure wave slopes of ocean waves in
real time. An imaging polarimeter measures the polarization ellipse, and hence the
degree of polarization and its orientation, by acquiring a number of images each of which
analyzes a different polarization state. By knowing the geometry of the camera and its
relationship to the sea surface and the measured polarization quantities, the wave slope
can be extracted. We have developed and tested such an instrument with good results.
For this talk, the four camera imaging polarimeter operating in the visible at 60 frames
per second will be presented. The polarimeter design, calibration procedures, and the
data from several data acquisition programs using the instrument will be presented.
A four camera Stokes imaging polarimeter operating in the visible at 60 frames
per second will be presented. The polarimeter makes use of a beam splitter design which
allows the measurement of a full Stokes vector image (S0, S1, S2, and S3). The system
measures four images of a scene simultaneously. The polarimeter design, calibration
procedures, and initial data from the instrument are presented.
This paper presents the design of a visible band imaging polarimeter that can also function as a low light level intensity
imager. The polarimeter is based on the division of aperture approach, acquiring four subimages simultaneously on a
single CCD array. The system is currently designed to measure the first three normalized components of the Stokes
vector through polarization filtering on three of the four available channels. The fourth channel remains unfiltered for
radiometric sensing in low power situations. The opto-mechanical design allows for ease of assembly without requiring
active alignment techniques, while maintaining a modular system. The modular nature provides a robust, flexible sensor
that can be tailored to multiple applications.