similar optical design can be used in adaptive optics in astrophysics. Mitsubishi Electric Research Laboratories's (MERL) light field camera is based on the principle of optical heterodyning and uses a printed film (mask) placed close to the sensor. Any hand-held camera can be converted into a light field camera using this technology by simply inserting a low-cost film on top of the sensor. A mask-based design avoids the problem of loss of resolution, since a high-resolution photo can be generated for the focused parts of the scene. Pelican Imaging has thin multi-camera array systems intended for consumer electronics. Pelican's systems use from 4 to 16 closely spaced micro-cameras instead of a micro-lens array image sensor. Nokia invested in Pelican Imaging to produce a plenoptic camera system with 16-lens array that was expected to be implemented in Nokia smartphones in 2014. Pelican moved to designing supplementary cameras that add depth-sensing capabilities to a device's main camera, rather than stand-alone array cameras. A collaboration between University of Bedfordshire and ARRI resulted in a custom-made plenoptic camera with a ray model for the validation of light-field geometries and real object distances. In November 2021 the German-based company K|Lens announced the first light field lens available for any standard lens mount on Kickstarter. The project was canceled in January of 2022. The modification of standard digital cameras requires little more than suitable sheets of micro-lens material, hence a number of hobbyists have produced cameras whose images can be processed to give either selective depth of field or direction information. Applications In a 2017 study, researchers observed that incorporation of light field photographed images into an online anatomy module did not result in better learning outcomes compared to an identical module with traditional photographs of dissected cadavers. Plenoptic cameras are good for imaging fast-moving objects that outstrip autofocus capabilities, and for imaging objects where autofocus is not practical such as with security cameras. A recording from a security camera based upon plenoptic technology could be used to produce an accurate 3D model of a subject. Software Lytro Desktop is a cross-platform application to render light field photographs taken by Lytro cameras. It remains closed source and is not maintained since Google’s acquisition of Lytro. Several open-source tools have been released meanwhile. A Matlab tool for Lytro-type camera processing can be found. PlenoptiCam is a GUI-based application considering Lytro's and custom-built plenoptic cameras with cross-platform compatibility