Illumination plays an important role in optical microscopy. Köhler illumination, introduced more than a century ago, has been the backbone of optical microscopes. The last few decades have seen evolution of new illumination techniques meant to improve certain imaging capabilities of the microscope. Most of them are however not amenable for wide-field observation and hence have restricted use in microscopy applications like cell biology and micro-scale profile measurements. The method of structured illumination microscopy has developed as wide-field technique for achieving higher performance. Additionally, it is also compatible with existing microscopes. This method consists of modifying the illumination by superposing a well-defined pattern, either on the sample itself or on its image. Computational techniques are applied on the resultant images to remove the effect of the structure and to obtain the desired performance enhancement. This method has evolved over the last two decades and has emerged as a key illumination technique for optical sectioning, super-resolution imaging, surface profiling and quantitative phase imaging of micro-scale objects in cell biology and engineering. In this review, we describe various structured illumination methods in optical microscopy, and explain the principles and technologies involved therein.
The structured illumination microscopy (SIM) is also a technique that utilizes illumination pattern for various purposes such as super-resolution, surface profiling, and phase imaging REF .
Structured illumination microscopy
Advances in Optics and Photonics
Physics