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We report the simulation of an adaptive interferometric null test using a high-definition phase-only spatial light modulator (SLM) to measure form and mid spatial frequencies of a freeform mirror with a sag departure of 150 μm from its base sphere. A state-of-the-art commercial SLM is modeled as a reconfigurable phase computer generated hologram (CGH) that generates a nulling phase function with close to an order of magnitude higher amplitude than deformable mirrors. The theoretical uncertainty in form measurement arising from pixelation and phase quantization of the SLM is 50.62 nm RMS. The calibration requirements for hardware implementation are detailed. © 2019 Optical Society of America https://doi.org/10.1364/OL.44.002000 

Freeform optical components enable significant advances for optical systems. A major challenge for freeform optics is the current lack of metrology methods with measurement uncertainty on the order of tens of nanometers or less. Towards addressing this challenge, optical coherence tomography (OCT) is a viable technique. In the context of low uncertainty metrology, the design requirements pertaining to the sample arm of an OCT metrology system are explicitly addressed in this paper. Two telecentric, broadband, diffraction limited, custom objective lens designs are presented with their design strategies. One objective lens was fabricated and experimentally tested for wavefront performance and telecentricity. This lens demonstrates near diffraction limited performance and a maximum deviation from telecentricity of 8.7 arcseconds across the full field of view, correlating to measurement uncertainty of less than 12 nm in simulation. The telecentricity test method developed completes the loop with respect to the design requirements and strategies presented and provides further intuition for telecentric lens designs in general. © 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement 

Freeform optical surfaces offer significant design opportunities but pose new challenges in metrology and manufacturing. Evolution in optics manufacturing processes have changed the surface spatial frequencies that must be measured. Optical surface definition is expected to be with respect to fiducials and datums which must be realizable at all stages of manufacture; uncertainty in that realization becomes important in some cases. Concurrent engineering is required, but appropriate data has not been collated for use by optical designers. One approach to providing such data is described.