Papers Published by Optical Perspectives Group

In this paper we step back from complex CGH patterns used to test aspheric and freeform optics to ask what can be done with the simplest CGH patterns and the high precision of pattern location on a photomask substrate4. We first describe the use of patterns of equally spaced concentric circles to create an axis in space perpendicular to the CGH plane, and the Fresnel zone patterns that produce points in space when illuminated with a point source of light.

Optical aspherical surfaces have become more widely used as they offer advantages such as improved image quality, compact design, increased light gathering, and reduced distortion. However, measuring aspherical surfaces presents challenges due to their non-spherical shapes. The primary difficulties include the complexity of surface geometries and the need for specialized metrology equipment. These challenges require advanced measurement techniques to ensure accurate characterization and quality control of aspherical surfaces in various applications. This paper introduces an innovative, AI-driven solution for the measurement of aspherical surfaces within the image space, offering a flexible optical metrology tool for measuring aspherical surfaces. This approach is characterized by its ability to deliver rapid and cost-effective integration without the need for custom, complex optics.

Optical aspherical surfaces have become more widely used as they offer advantages such as improved image quality, compact design, increased light gathering, and reduced distortion. However, measuring aspherical surfaces presents challenges due to their non-spherical shapes. The primary difficulties include the complexity of surface geometries and the need for specialized metrology equipment. These challenges require advanced measurement techniques to ensure accurate characterization and quality control of aspherical surfaces in various applications. This paper introduces an innovative, AI-driven solution for the measurement of aspherical surfaces within the image space, offering a flexible optical metrology tool for measuring aspherical surfaces. This approach is characterized by its ability to deliver rapid and cost-effective integration without the need for custom, complex optics.

Bessel beams have found use in the alignment of transmissive optics for some time. They are also used for the alignment of reflecting optics when used in the imaging mode, that is, when the wavefront is near spherical. However, there are cases where it would be useful to use the Bessel beam for alignment of far-off axis aspheres to order to get the asphere aligned close enough to its final position that light will go through the system in the imaging mode. In another mode, the Bessel beam is used to determine the normal to a free form surface.

The use of artificial intelligence (AI) software for wavefront sensing has been demonstrated in previous studies [1], [3]. In this work, we have developed a novel approach to wavefront sensing by coupling an AI software with an Autostigmatic Microscope (AM). The resulting system offers optical component and system testing capabilities similar to those of an interferometer used in double pass, but with several advantages. The AM is smaller, lighter, and less expensive than commercially available interferometers, while the AI software is capable of reading out Zernike coefficients, providing real-time feedback for alignment.

The Point Source Microscope (PSM) is used to find five aberrations related to the symmetries of the autostigmatic image viewed when aligning aspheric mirrors to a point along an axis. These five aberrations exactly match in number the five degrees of mechanical freedom required to align the mirror to an axis and thus provide an exact solution to a unique focus and alignment to an axis. We show how the PSM is used to capture and analyze a set of images as the PSM is moved through focus using the symmetry properties of the image.