## Abstract

Freeform optics have emerged as promising components in diverse applications due to the potential for superior optical performance. There are many research fields in the area ranging from fabrication to measurement, with metrology being one of the most challenging tasks. In this paper, we describe a new variant of lateral shearing interferometer with a tunable laser source that enables 3D surface profile measurements of freeform optics with high speed, high vertical resolution, large departure, and large field-of-view. We have verified the proposed technique by comparing our measurement result with that of an existing technique and measuring a representative freeform optic.

© 2014 Optical Society of America

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### Equations (5)

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(1)
$$\begin{array}{l}I\left(x,y;k\right)={I}_{0}\left(x,y;k\right)\left\{1+\mathrm{cos}\left[2\left(k-{k}_{0}\right)\Delta W\left(x,y\right)+2k\Lambda \right]\right\}\\ ={I}_{0}\left(x,y;k\right)\left[1+\mathrm{cos}\left(\Phi \left(x,y;k\right)+2k\Lambda \right)\right]\\ ={I}_{0}\left(x,y;k\right)+{I}_{1}\left(x,y;k\right){e}^{j2k\Lambda}+{I}_{1}{\left(x,y;k\right)}^{*}{e}^{-j2k\Lambda}.\end{array}$$
(2)
$$\text{FT}\left[I\left(x,y;k\right)\right]={\Gamma}_{0}\left(x,y;{f}_{k}\right)+{\Gamma}_{1}\left(x,y;{f}_{k}-\Lambda \right)+{\Gamma}_{1}{\left(x,y;{f}_{k}+\Lambda \right)}^{*}.$$
(3)
$$\begin{array}{l}{\text{FT}}^{-1}\left[{\Gamma}_{1}\left(x,y;{f}_{k}\right)\right]={\text{FT}}^{\text{-1}}\text{FT}\left[\frac{1}{2}{I}_{0}\left(x,y;k\right){e}^{j\Phi \left(x,y;k\right)}\right]\\ \text{=}\frac{1}{2}{I}_{0}\left(x,y;k\right){e}^{j\Phi \left(x,y;k\right)}.\end{array}$$
(4)
$$\Delta W=\frac{1}{2}\frac{\partial \Phi \left(x,y;k\right)}{\partial k}.$$
(5)
$$\Delta W=\frac{1}{2{k}_{0}}\mathrm{arg}\left[{\Gamma}_{1}\left(x,y;{f}_{k}\right)\right].$$