Optically, the operation of the liquid crystal layer of the Forth Dimension Displays microdisplay (ForthDD) can be described as an electrically reconfigurable wave plate which rotates the polarization of the incoming light. The birefringence of the liquid crystal material can also be used to introduce a phase delay, allowing the FLCoS to be employed as a Spatial Light Modulator (SLM) operating as a high speed binary (0 or π ) phase modulator.
Amongst the varied and interesting applications of a binary phase modulator are structured illumination microscopy (SIM), holographic light projection (HLP), holographic optical tweezers (HOT) and holographic data storage.
Structured Illumination Microscopy
Structured Illumination Microscopy (SIM) is a measurement technique which involves the projection of structured laser light onto a biological sample with fluorescent markers. The grating structure combines with the sample structure to produce Moiré patterns. Use of multiple grating patterns in different orientations, along with analysis algorithms, increases the resolution of the microscope beyond the standard diffraction limit.
ForthDD spatial light modulators are ideal for producing fully reconfigurable grating patterns which can be cycled through at high speed. This offers great flexibility to the measurement system and reduction of the sample measurement time.
Recognising the benefits of the increased resolution in leading edge imaging techniques, the first production shipment of a QXGA-3DM has been sent to its established customer Howard Hughes Medical Institute (HHMI) for use by Nobel Prize for Chemistry 2014 winner Dr. Eric Betzig’s team. Lattice light sheet microscopy, a new imaging platform developed at Janelia Farm, lets biologists see 3-D images of subcellular activity in real time.
Holographic Optical Tweezers
In holographic optical tweezers (HOT), one of the most important tasks is that of steering a laser beam, which corresponds to translating an optical trap. ForthDD’s spatial light modulators are capable of producing multiple traps and steering them in real time at up to 100Hz (driven by the graphics card video refresh rate). Further, the extremely fast response time of the ferroelectric liquid crystal means that the optical traps do not “dim” when moved, which is a common problem in many nematic based liquid crystal SLM devices.
Holographic data storage combines the technologies of volume data recording and holography. When information is stored throughout the volume of the recording medium, a far greater storage density can be achieved compared to traditional surface recording technologies. In addition, the holographic approach allows very fast data transfer rates as information is stored a “page” at a time instead of one bit at a time. The ForthDD all-digital, ferroelectric spatial light modulator technology enables the lossless high-speed data transfer that is required for this demanding application.