Apr 08

MIT Boosts Efficiency of Lensless Single Pixel Cameras by Factor 50

MIT Boosts Efficiency of Lensless Single Pixel Cameras by Factor 50. Original image (top), single-pixel camera image (50 and 2500 exposures, respectively; second row), and reconstructions from ultrafast sensing (third and fourth rows, 50 exposures using 100 and 20 picosecond sensing, respectively). Image: Satat et al., 2017. Today’s conventional cameras require a set of highly precise lenses and a large array of individual light sensors. This general blueprint limits the application of cameras for new uses, e.g. in ever-thinner smartphones, or in spectra outside the visible light range.
To overcome these limitations and completely rethink the basics of imaging, researchers from Rice University, Heriot Watt University and the University of Glasgow (among others) have recently developed a “compressive sensing” concept camera which uses only a single pixel and no lens whatsoever to record pictures using computational imaging. The trick here lies in the light source, which illuminates the scene using a series of defined black-and-white patterns (coded mask). Based on changes in the resulting light intensity across many exposures, the single pixel camera can then infer the position of objects and patterns in the scene.
Until recently such single-pixel systems required a large number of exposures in the range of 2000 or more. Now, Guy Satat and colleagues from MIT‘s Camera Culture lab have combined single-pixel camera with another cutting-edge technology, ultrafast femto- or picosecond light sensors. Looking not only at the intensity changes across masked illumination bursts, but also within individual bursts, the researchers are able to break up the signal into light reflected from different distances in the scene. This brings the number of required exposures down from 2500 to just 50 in the example outlined in the paper and video. Moving from a single pixel to several light-sensing pixels, placed in a defined sensor pattern, this number can be further reduced without losses in image qualilty. Continue reading

Jan 09

Paper: How to use a First-Generation Lytro Camera for Light Field Microscopy

Almost as soon as the original Lytro camera was released, enthusiasts tried to find an easy way to combine light field imaging with microscopes. However, due to the optical characteristics of a microscope (especially the strong f-number mismatch), those attempts had only limited success.

Paper: How to use a First-Generation Lytro Camera for Light Field Microscopy (picture: Mignard & Ihrke 2015)
Paper: How to use a First-Generation Lytro Camera for Light Field Microscopy (picture: Mignard & Ihrke 2015)

In a recent publication, Loïs Mignard-Debise and Ivo Ihrke from INRIA Bordeaux in France presented the findings of their experiments to use off-the-shelf hardware (i.e. a first-generation lytro camera and camera lenses or microscope objectives) for a working light field microscope. Continue reading

Aug 17

Ricoh Patents Dynamically Adjustable Multimode Lightfield Imaging System

Ricoh Patents Dynamically Adjustable Multimode Lightfield Imaging System (Fig. modified from Shroff & Berkner 2014) Ricoh researchers Sapna A. Shroff and Kathrin Berkner have lodged a patent application that describes a new way to dynamically adjust the recording parameters of a light field camera. The US Patent and Trademark Office has recently published patent application US20140192255, entitled “Dynamic Adjustment of Multimode Lightfield Imaging System Using Exposure Condition and Filter Position”, in which the authors use a non-homogeneous filter module at the pupil plane of a multimode imaging system, which can be moved and thus used to modify the imaging system’s exposure conditions. Continue reading

May 04

Light Field Microscope: New Imaging System Allows Real-Time 3D Microscopy

Light Field Microscopy: New Imaging System Allows Real-Time 3D Microscopy (image: Kim et al. 2014) One of the most exciting fields in science where light field imaging (or plenoptic imaging) has a great potential is microscopy: Not only is the depth of field very limited in microscopy, it also enables us to observe things much smaller than what the eye can see. Extended depth of field and 3D reconstruction would offer many opportunities, such as to better understand the three-dimensional internal structure of plant- or animal cells and tissues, to name just one example.
3D imaging using multi-camera approaches is very difficult in microscopy due to space limitations and the strong effects of parallax, but light field imaging can solve these problems. Until now, however, light field microscopy is still largely defined by resource-intensive post-processing, which limits real-time applications and observations.

In a recent publication in the journal Optics Express, researchers from Seoul National University and Harvard Medical School in Boston present a novel light field microscopy system that enables light field microscopy with real-time 3D display. Continue reading

Jul 07

Lightfield 3D Microscopy: Raytrix Showcases the R5µ

Lightfield 3D Microscopy: Raytrix Showcases the R5µ (picture: Raytrix) German Light field specialist Raytrix has just added another use case of their range of plenoptic cameras for scientific and industrial use: The new Lightfield 3D Microscopy webpage page makes a first mention of the R5μ light field camera setup, which is optimized specifically for microscopy applications.
In the picture, Raytrix’ R5 high-speed video lightfield camera (model number R5-M-E-GE-A260-GS-A) is shown in conjunction with a Solino 0.8x High Resolution Tube for Fixed Magnification (177 mm, C-mount camera interface, Art.No. 045-200162), an objective adapter and a Leica objective lens for 10x magnification.

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