Characterization of a 10” Schmidt-Cassegrain telescope using HASO R-Flex™ Imagine Optic’s HASO™ wavefront sensors, based on patented Shack-Hartmann technology, are excellent tools for the precision metrology of optical systems. Easy to use and integrate, HASO’s wide dynamic range and exceptional precision allow users to characterise a wide range of dioptrical and catadioptrical systems. This document explains how using HASO R-Flex 32 enabled us to precisely characterize the wide-aperture optical system found in a SchmidtCassegrain telescope. The data acquired provided the information necessary to asses the effects of the secondary mirror’s misalignment and to use that information to correct its alignment.

Configuring the test The diagram below shows an easy to configure method for measuring the wavefront error (WFE) of a SchmidtCassegrain telescope using an Imagine Optic HASO R-Flex 32 on a standard optical workbench. In this example, the source was adapted to the numerical aperture of the telescope by using a standard f/10 objective. Laser Diode (included with all models) being attached to a HASO R-Flex 32 with an f/10 objective. autocollimation mirror primary mirror HASO R-Flex secondary mirror source Schmidt plate Measuring the telescope’s WFE The first step in measuring the telescope is choosing...

2) Aligned HASO R-Flex in-line with the telescope's aperture (rotation of the autocollimation mirror) 3) Measured the telescope's WFE in referenced mode using the data file acquired in step 1. Before alignment - The wavefront display windows below shows us that there was a significant field aberration. When HASO R-Flex was aligned to the telescope's mechanical axis we discovered that the secondary mirror orientation had introduced coma aberrations into the optical system. After alignment - HASO's real-time measurement features enabled us to correct the telescope's alignment and observe the effects...