Freeform surface selection based on parametric fitness function using modal wavefront fitting.

We present an analytic methodology to guide the selection of a surface within an optical design to apply freeform optimization. The methodology is discussed in the context of other means currently available, such as human intuition, aberration theory, and other direct surface construction methods. We describe the selection criteria for our proposed method and provide the form of the parametric fitness function used to combine the criterion. Finally, a case study comparing a design optimization procedure guided by the proposed methodology to human intuition is presented based on a real instrument designed for a millimeter-wave astronomy application. The methodology is shown to be effective even in the case of an optical system with a large number of freeform/optical surfaces. The proposed approach provides an objective and scalable solution to guide freeform optical system design by aiding a human's design intuition.

Simultaneous multi-segmented mirror orientation test system using a digital aperture based on sheared Fourier analysis.

This paper presents a simultaneous multi-segmented mirror orientation test system (SMOTS) using localized sheared images. A CMOS camera captures images of reflected 2D sinusoidal patterns from the test mirrors as their orientation changes. Surface orientation is measured to within 0.8 µrad (0.16 arcseconds) for a flat mirror. In addition, we measure the variation of seven mirror segments simultaneously. Furthermore, SMOTS is applied to measure the orientation of two concave mirrors with an accuracy of 2.7 µrad (0.56 arcseconds). The measurement time for seven segments is 0.07 s. This technique can monitor the mirror segment orientation in an open/closed-loop for various optical setups.

Instantaneous phase shifting deflectometry.

An instantaneous phase shifting deflectometry measurement method is presented and implemented by measuring a time varying deformable mirror with an iPhone ® 6. The instantaneous method is based on multiplexing phase shifted fringe patterns with color, and decomposing them in x and y using Fourier techniques. Along with experimental data showing the capabilities of the instantaneous deflectometry system, a quantitative comparison with the Fourier transform profilometry method, which is a distinct phase measuring method from the phase shifting approach, is presented. Sources of error, nonlinear color-multiplexing induced error correction, and hardware limitations are discussed.