Fast F/1 reflective Maksutov microscope objective

20150206_2Originally suggested by Maksutov, a Maksutov microscope objective (or eyepiece) is a reverse Gregorian type reflective objective. It has high numerical aperture and has corrected spherical, coma and color aberrations. It requires a field flattener to correct the field curvature, but for on-axis observations, it has a long working distance and short total track.

Originally published 6.2.2015 by Jani Achrén. Read the rest from here.


Ways to trip by using stock optical components

20141107_1Stock optical components are very attractive option for a developer. You get parts ASAP, keep prototyping costs down and one gets fitting optomechanical parts to go, and you can do all by yourself as well. Then again, there are whole factories spewing out same parts to your competitor, with same instructions and howto’s. So it comes down to this: what SPECIAL can you do with stock optical parts? Turns out, quite a lot. However, they might need an optical engineer to pull them off. I’ll go through some examples of common tripping points of stock optical components, and a short description on how an optical designer can overcome them.

Published 7.11.2014 by Jani Achrén, and he invites you to read the rest here.

Designing Cassegrain type telescopes with spreadsheet


Designing a reflective telescope system with paraxial optics is really easy, since there is no refraction involved. Pre-design calculations offer final solutions in most cases. Here I will demonstrate use of spreadsheet for designing a Cassegrain type reflective telescope.

Originally published 22.2.2013 by Jani Achrén. You can know more in here and here‘s the xls compatible spreadsheet.

Low-cost interferometric testing for conical surfaces

A two-slit interferometric wavefront error measuring technique combines high sensitivity and low-cost components.

Testing of conical surfaces for mirrors or lenses most often require interferometry and with it, expensive devices to detect wavefront aberrations.

A two-slit Interferometric wavefront error measuring technique, first deviced by Yrjö Väisälä of Tuorla Observatory, combines high sensitivity (much higher than with traditional Foucault or Ronchi tests) with few layout components most probably already in posession of ATM mirror manufacturers. The principles of this test have been developed into an interferometric Hartmann test.

Originally published 14.2.2013. You can read more about it here.