A frequency-response-optimized Shack-Hartmann zonal wavefront reconstructor based on Fan's model.

This paper introduces an optimized method for zonal wavefront reconstruction utilizing Fan's model, specifically tailored to enhance the frequency response. Analysis of the system frequency response demonstrates a 27% increase in bandwidth compared to the Southwell model. Examination of reconstruction errors at various frequency points reveals consistently smaller values when compared to the Southwell model. Validation through numerical simulations and real experiments underscores the superior performance of the proposed reconstructor, particularly noticeable at higher response levels within the mid- and high-frequency domains.

Distance and depth modulation of Talbot imaging via specified design of the grating structure.

For positioning Talbot encoder and Talbot lithography, etc., properties manipulation of Talbot imaging is highly expected. In this work, an investigation on the distance and depth modulation of Talbot imaging, which employs a specially designed grating structure, is presented. Compared with the current grating structure, the proposed grating structure is characterized by having the phase layers with uneven thicknesses. Such a specific structural design can cause the offset of Talbot image from its nominal position, which in turn generates the spatial distance modulation of self-imaging and imaging depth expansion. Theoretical analysis is performed to explain its operating principle, and simulations and experiments are carried out to demonstrate its effectiveness.

Optical transmittance measurement system for coated elements with low transmittance.

The low-transmittance elements required for a high power laser facility have stringent specifications about transmittance. To validate optic performance against specifications, a metrology system for transmittance is proposed. The system is composed of a laser source, an integrating sphere, a power meter, and four uncoated wedged glasses. A relative measurement method is adopted, which is that the surface reflectivity of uncoated glass is used as the reference to compare with the sample's transmittance. The systematic feature is that uncoated wedged glasses are applied to split and reflect beams, which not only avoid coating errors, but also make the two beam powers attenuate properly. Measurement results for a sample's transmittance are presented. Experiment and analysis show that the relative standard uncertainty (σ(T)/T) of measurement is 0.424%. This system is available for large-aperture elements.