Practical tolerancing example

Tolerancing is a vital stage that comes after the design phase, critical enough to warrant a re-design. It is a statistical evaluation balancing quality, cost and end-user satisfaction. The purpose of tolerancing is to determine the maximum manufacturing errors, for both optical and optomechanical components, that still produce a system with acceptable performance. Here I discuss two tolerancing techniques, Inverse Limit and Sensitivity.

Published 23.9.2018 by Jani Achrén who would be crazy happy if you’d read the rest here.

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Achromatization over wide spectral range

The calibration unit of the ESO SOXS telescope which Incident Angle is developing for FINCA at the time of writing this, operates over a wide spectral range from VIS to NIR. In order to achromatize the collimating lenses, the indices of refraction had to be recalculated.

Published 17.9.2018 by Jani Achrén, who implores you to read more, including all the publications he was awarded co-authorship from working on this project.

Case study: Using an achromatic objective as its own focal reducer

Commercial telescopes are more often than not provided with a focal reducer, which enables the customer to use the telescope also for astrophotography. Here I introduce two cases where a second objective unit identical to the primary unit serves as the focal reducer to the first unit which reduces not only focal length but also design and manufacturing costs.

Published 6.9.2018 by Jani Achrén, who would love to tell you more here.

A folded Cassegrain telescope saves up space and a whole world of troubles

A folded Cassegrain type telescope objective is nothing new, but given present advancements in optical manufacturing, a worth reconsidering.

Cutting the optical tube length in half with a flat mirror and moving the secondary to the center of primary mirror hole is not a new idea and does nothing to help manufacture and assembly. Instead making a single mirror with a binary surface, i.e. one radius at inner zone and another in outer zone, a whole world of manufacture and assembly problems can be avoided. Assembly problems would eliminate themselves, and manufacturing would get easier by making traditional manufacturing near impossible and forcing more advanced techniques.

Published 30.10.2016 by Jani Achrén, who explains more here.

Improving telescope objective with N-BK7 accessories

Giving new life to an old telescope design is quite possible and not necessarily expensive either.

I designed a generic Fraunhofer doublet telescope in order to design two accessories for it using nothing but Schott N-BK7 glass. Both accessories address the astigmatism in a doublet, flattening the image plane for a wider field of view of the original doublet.

Published 25.9.2015 by Jani Achrén. More marvels here!