Anywhere Light Goes™ Blog
A blog about optical design, build, test and more.
Opto-mechanical Design Challenges for High Performance Aerial Imaging
Optikos develops optical systems for a wide variety of applications and markets, from medical diagnostic and surgical, to augmented reality and gaming, to automotive, tactical and consumer products. The best aspects of engineering for our customers involve design of systems that perform “Anywhere Light Goes.” Aerial imaging is one of the more challenging of these design arenas, particularly regarding optical imaging performance and stability. Aerial imaging presents many optical and mechanical challenges for lens design. Earth mapping requires high resolution over the field of view. ISR applications may require exceptional color correction and co-boresighting for multispectral and hyperspectral imaging. Stray light mitigation for glare within the scene and sun near the aperture can be stressing for down-looking and side-looking systems. ...
Measuring at the Correct Conjugate
When evaluating lens performance it is critical for the test system to properly simulate the lens’s image and object conjugates. Testing off conjugate will produce results that can give a false sense of confidence and when it comes time to use the lens as intended you can get an unpleasant surprise. In that light, the two most common errors we have seen people make when measuring MTF are: Testing an infinite conjugate optic with a finite conjugate target. Simulating an infinitely distance object can be difficult. Often, the assumption is made that an infinite object can be approximated by a finite, but relatively large object distance, such as the hyper-focal distance. In many cases this can be shown to be...
Design for Test—Plan Your Metrology Early
Most of us have heard of “Design for Manufacture” or DFM. This is a core tenet of the Optikos design philosophy and it is critical for optical hardware where tolerances are measured in microns, assembly and alignments can be labor intensive, and serviceability is a necessity for long-life instruments. Less well known, but just as important is “Design for Test.” A critical and underappreciated component of DFM is making sure you can (and know how to) test key aspects of your manufactured product. The Design for Test process includes not only designing a test bench, but also designing appropriate features into the product to enable streamlined testing. Planning how to align and test your optical product can be time consuming...
Encircled and Ensquared Energy Explained (EEEE!!!)
Here at Optikos we spend a lot of time measuring the imaging quality of lens assemblies. In most cases, traditional measurements of Modulation Transfer Function (MTF) are well correlated with lens performance in its intended application. However, in some cases, characterization of encircled and/or ensquared energy serve as better indicators of lens performance. This is true for lenses designed to focus as much energy as possible into a circular or square area that corresponds to a critical dimension in the system detection sensor (detector active area, thermal array pixel, etc.). Maximizing resolution, or producing high contrast in the smallest image details is not required and, given the clear benefits for manufacturability and cost, it is beneficial to NOT design a...
Nearly 40 Years of MTF and Going Strong
Then and now: Roy holding a copy of the original OpTest manual from 2001, featuring his photo on the cover. Let’s take a trip down memory lane. In the mid-1990s when I was a young engineer at Optikos Corporation, I vividly remember CEO Stephen Fantone imploring my boss, Peter Carellas, to get back to work on a project Steve called, “that four-letter word!” The word in question was “book” and the book Peter was working on would become the booklet, published in 1999, “How to Measure MTF and Other Properties of Lenses,” a compilation of articles written by Optikos staff that described techniques for measuring Modulation Transfer Function (MTF) and several other lens characteristics. Even now, more than 20 years...
