Heliostat alignment techniques

The alignment of optical systems is crucial for proper operation. Heliostat mirror facet alignment entails two operations: focusing and canting. Mirror focusing is the slight bending of the facet surface into a concave shape. Heliostat canting consists of tilting each facet to direct the reflected sunlight at a single aimpoint. Two techniques have been developed.

In the flux map fitting procedure, canting errors are found by matching computed flux maps to the experimental ones. The video shows the evolution of the optimization algorithm applied to a heliostat.

The target reflection method compares actual and theoretical images of the reflection of a known target on the heliostat facets. A neighbor heliostat can be used as target. From the comparison with the camera pinhole model, both canting and focusing errors are determined.

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