There is provided a sensor device, a sensor module, and methods for determining a position of a light source. The sensor device comprises a plurality of sensor units, each sensor unit having a respective sensor area. The sensor device also comprises a mask disposed above the plurality of sensor units and arranged such that incident light from the light source will illuminate different regions of the sensor area of each one of the sensor units depending on the position of the light source relative to the sensor device. The position of the light source may therefore be determined based on which regions of the sensor area of the sensor units are illuminated. Further, each sensor unit is arranged to be controlled by a respective unit controller to determine the position of the light source.

The invention provides in one aspect a fast digital light source tracker aboard a moving ground-based or airborne platform. The tracker consists of two rotating mirrors, a lens, an imaging camera, and a motion compensation system that provides the Euler angles of the mobile platform in real time. The tracker can be simultaneously coupled to UV-Vis and FTIR spectrometers, making it a versatile tool to measure the absorption of trace gases using the light source's incoming radiation.

An instrument (20) determines the attitude of a spacecraft (3) on which it is mounted, by interacting incident light (11) from the Sun with one or more light conditioning elements (12) and thereby forming a diffraction pattern at a photo-sensitive detector (13). The intensity distribution of light on the detector (13) is dependent on the angle of incidence of the light (11). An on-board computer (16) determines a direction vector to the Sun based on the light diffraction pattern detected by the detector (13).

Methods and apparatus for tracking movement over the ground or other surfaces of a buried utility locator during a utility locate operation are disclosed.

Described are systems and methods for direct sun imaging by a star tracker. Disclosed in a certain example is a direct sun imaging star tracker that includes an imaging sensor and a baffle. The baffle includes a star port, a sun port, and a beam splitter. The star port is configured to image first viewing environment while the sun port is configured to image a second viewing environment that includes the sun. The beam splitter is configured to combine electromagnetic radiation from the star port and the sun port into a combined image. In various examples, the systems and techniques described herein allow a star tracker to simultaneously view both the sun and the stars.

A solar monitoring system for measuring solar radiation intensity comprising a tracking unit having two-axis movement comprising, an image capturing head mounted with first and second irradiation measuring units, and a controller. The first irradiation measuring unit comprises a direct normal irradiance (DNI) sensor and the second irradiation measuring unit includes a diffuse horizontal irradiance (DHI) sensor and a global horizontal irradiance (GHI) sensor. The controller receives inputs from the sensors or a software program configured to control orientation of the image capturing head so that the DNI sensor is always exposed to the sun, and the shading disc is always directly between the DHI sensor and the sun.

A method is provided. The method comprises: receiving incident light, from an object surface, on a top surface of a holographic optical field flattener (HOFF); transforming direction of light, with a hologram, if the light is incident on a portion of the HOFF at an angle equal to a non-zero field angle of the portion; and emitting transformed light from a bottom surface of the HOFF.

In a method for determining orientation of an object, raw image data of the sky is recorded using a sky polarimeter. One or more of Stokes parameters (S0, S1, S2), degree of linear polarization (DoLP), and angle of polarization (AoP) are calculated from the image data to produce a set of processed images. Last known position and time data of the object are obtained, and a known Sun azimuth and elevation are calculated using the last known position and time data. Roll and pitch of the object are found, and the roll and pitch data are used to find a zenith in the processed images. The yaw/heading of the object is determined using the difference between a polarization angle at the zenith and a calculated Sun azimuth.

A system for determining a new orientation and/or position of an object comprises a sky polarimeter configured to record image data of the sky, a signal processing unit, and logic configured to receive and store in memory the image data received from the sky polarimeter. The logic calculates the Stokes parameters (S.sub.0, S.sub.1, S.sub.2,), DoLP, and AoP from the image data, detects obscurants and filters the obscurants (such as clouds and trees) from the image data to produce a filtered image. The logic is further configured to find the Sun and zenith in the filtered image, and to determine the roll, pitch, yaw, latitude and longitude of the object using the filtered image. A method for determining a new position/orientation of an object comprises recording raw image data using a sky polarimeter, calculating S.sub.0, S.sub.1, S.sub.2, DoLP, and AoP from the image data, detecting obscurants and filtering the obscurants from the image data to produce a filtered image, obtaining last known position/orientation data of the object, finding the Sun and zenith in the filtered image, and determining the roll, pitch, yaw, latitude and longitude of the object using the filtered image.

The invention provides in one aspect a fast digital light source tracker aboard a moving ground-based or airborne platform. The tracker consists of two rotating mirrors, a lens, an imaging camera, and a motion compensation system that provides the Euler angles of the mobile platform in real time. The tracker can be simultaneously coupled to UV-Vis and FTIR spectrometers, making it a versatile tool to measure the absorption of trace gases using the light source's incoming radiation.