Electronic interface for high-frame-rate electrically addressed spatial light modulators

The digital micromirror device DMD is widely used in visible light projection, special-purpose spatial light modulation, and infrared scene simulation, due to its high resolution, uniformity and energy concentration. In some applications that require high frame rate scene image display, it is necessary to ensure that the DMD displays high gray level images at a high frame rate. However, the display frame rate of the pulse width modulation (PWM) method is limited by the minimum time required for DMD loading data, unable to achieve high frame rate display. Although the DMD binary display mode can meet the requirements of high frame rate display, it cannot meet the requirements of high gray level. The paper proposes an image display method that uses light source and DMD to synchronize modulation. Decompose the high-order gray image into bit planes according to the gray threshold, and the DMD displays each bit plane in binary mode under the trigger of an sync pulse. The intensity of the illumination laser source is modulated by an acousto-optic modulator to match the bit plane and the radiated laser power. This method makes use of the function of high frame rate display in DMD binary mode cooperate with light intensity modulation of illumination laser source, and realizes high frame rate and high dynamic range image display. With this method, the maximum frame rate of 8-bit gray level image with 1920 ×1080 resolution can reach 2KHz. The experimental system has realized 200Hz frame rate display of 8-bit gray level image with 1920 ×1080 resolution.

Surface-stabilized antiferroelectric liquid crystals (AFLCs) and V-shape smectics share the spontaneous generation of intermediate transmission states, i.e. analogue grayscale. On the other hand, liquid crystal on silicon (LCOS) appears to be a promising alternative to thin-film transistors (TFTs) in the preparation of reflective microdisplays and spatial light modulators (SLMs). The feasibility of preparing LCOS SLMs using AFLC and V-shaped LCs has been analyzed. A comparative study of a number of AFLC and V-shape materials as candidates for LCOS SLMs has been carried out. Test cells below 1 µm have been prepared using an ITO-coated transparent glass plate and an aluminized silicon back plate mimicking the actual LCOS device. AFLC waveforms compatible to low-voltage operation of the silicon backplane have been demonstrated. V-shape waveforms have been designed and demonstrated as well. The results show that both LC families may be employed in this specific application. Dynamic behavior, with frame rates over 200 Hz, is especially remarkable.

This paper presents our implementation of a multi-view autostereoscopic 3D display system by using time-multiplexing approach, digital micro-mirror devices (DMD), and the optical Wedgereg. The whole system consists of three major parts: high frame rate DMD projector, an active shutter, and an optical Wedgereg. This research investigates and develops the approaches to interface and control DMDs at very high bit rates and ultra-high frame rates to drive a novel flicker-free 3D flat panel device, with a wide viewing area and without need of special viewing glasses or head-tracking system. It needs to design a digital interface circuit capable of receiving video image data in a conventional format and translating it into a form appropriate for display on a DMD light modulator. This approach differs from existing ones in that it facilitates the modulation of the DMD to achieve much high frame rates, though with a trade-off in greyscale resolution. The outcomes of this research will have the great potential for commercialising the autostereoscopic display systems

The speed of most parallel-aligned liquid-crystal-on-silicon (LCoS) spatial light modulators (SLMs) is limited to the video rate of their drivers, which is a limitation for high-speed applications. However, the LCoS SLM presented here has a driver allowing a frequency range of up to 1011 Hz. Using the static phase modulation characterization and the static lookup table (LUT), the phase modulation characterization versus frequency shows that the SLM can operate at around 130 Hz or even higher for small phase changes and at 32 Hz for extreme phase changes. A dynamic calibration is carried out, and we propose a method allowing an increase of the frame rate while maintaining a maximum phase modulation of 2pi. Experimental results of dynamic diffractive optical elements displayed on the SLM at a frame rate of 205 Hz show that the dynamic LUT improves the reconstruction quality.

The use of flat panel detectors in computed tomography (CT) systems can improve resolution, reduce system cost, and add operational flexibility by combining fluoroscopy and radiography applications within CT systems. However, some prior studies have suggested that flat panel detectors would not perform well in CT applications due to their lack of high dynamic range, lag artifacts, and inadequate frame rate. The purpose of this study was to perform a physical evaluation of a prototype flat panel detector capable of high frame rates and extended dynamic range. The flat panel detector used had a pixel size of 194 microns and a matrix size of 2048x1536. The detector could be configured for several combinations of frame rate and matrix size up to 750 frames per second for a 512x16 matrix size with 4x4 binning. The evaluation was performed in terms of the MTF and DQE as a function of frame rate and exposure at the IEC RQA5 (~75 kVp, 21 mm Al) beam quality. The image lag was evaluated in terms of temporal-frequency dependent transfer function. Offset shift were also evaluated. Preliminary results indicate 0.1 MTF at 0.92 cycles/mm and DQE(0) of approximately 0.8, 0.6, 0.4, and 0.22 at 0.144, 0.065, 0.035, and 0.008 mR per frame exposures. The temporal MTF exhibited a low-frequency drop and a value of 0.5 at the Nyquist frequency. Offset shift was negligible. Considering high frame rate capabilities of the new detector, the results suggest that the detector has potential for use in real-time CT applications including CT angiography.

Structured light illumination has been used for several decades to extract three-dimensional information from surface topology. Most of the research and development has been in the light structuring methodology and the electronic processing while a unified theoretical description has been lacking. With the advent of programmable spatial light modulators having high frame rates, structured light illumination methods using spatial and temporal patterns are practical. We present structured light systems using spatial light modulation as communication systems and use communications theory in their description. This theory is applied to the specific method of successive binary light striping and the tradeoffs between surface encoding quality and processing speeds are discussed. Shannon's theorem of channel capacity provides an objective measure to evaluate some of these tradeoffs and compare a variety of different approaches to structured light illumination. Another result of our analysis is the unification of structured light projection with pattern recognition. Methods of image recognition using Fourier expansion via orthogonal pattern projection are presented. The results of this analysis establish some physical limitations which guide us to effectively utilize both the methodology and the technology applicable to both 3-D data acquisition as well as pattern recognition. Both numerical and experimental results are presented to demonstrate concepts.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We have developed a spatial light modulator (SLM) based microscope that uses diffraction to shape the incoming twophoton laser source to any arbitrary light pattern. This allows the simultaneous imaging or photostimulation of different regions of a sample with three-dimensional precision at high frame rates. Additionally, we have combined this microscope with a new class of two photon active neuromodulators with Ruthenium BiPyridine (RuBi) based cages that offer great flexibility for neuronal control.

The purpose of this study was to assess whether or not high frame rate (HFR) videos recorded using high-speed digital imaging (HSDI) improve the visual recognition of the motions of the laryngopharyngeal structures during pharyngeal swallow in fiberoptic endoscopic evaluation of swallowing (FEES). Five healthy subjects were asked to swallow 0.5ml water under fiberoptic nasolaryngoscopy. The endoscope was connected to a high-speed camera, which recorded the laryngopharyngeal view throughout the swallowing process at 4000 frames/s (fps). Each HFR video was then copied and downsampled into a standard frame rate (SFR) video version (30 fps). Fifteen otorhinolaryngologists observed all of the HFR/SFR videos in random order and rated the four-point ordinal scale reflecting the degree of visual recognition of the rapid laryngopharyngeal structure motions just before the 'white-out' phenomenon. Significantly higher scores, reflecting better visibility, were seen for the HFR videos compared with the SFR videos for the following laryngopharyngeal structures: the posterior pharyngeal wall (p=0.001), left pharyngeal wall (p=0.015), right lateral pharyngeal wall (p=0.035), tongue base (p=0.005), and epiglottis tilting (p=0.005). However, when visualized with HFR and SFR, 'certainly clear observation' of the laryngeal structures was achieved in <50% of cases, because all the motions were not necessarily captured in each video. These results demonstrate the use of HSDI in FEES makes the motion perception of the laryngopharyngeal structures during pharyngeal swallow easier in comparison to SFR videos with equivalent image quality due to the ability of HSDI to depict the laryngopharyngeal motions in a continuous manner.

The digital revolution changed film production and its aesthetics in many ways. Although motion is a defining feature of moving images, it is also one of their most problematic aspects because of blurred images or other signal processing artifacts. An artistic research project was conducted to test the effects of high frame rates (HFR) on visual perception. Typical camera movements were recorded in different frame rates (24 / 48 / 96 fps) to generate test sequences for a cinema experiment. 69 participants were measured with an SMI eye tracking device and a questionnaire in a within subjects design. The results show that the participants valued the higher image quality of HFR, but rated the standard frame rate as more realistic and indicated more presence. Moreover, HFR produced a higher number of fixations than the standard frame rate. Open questions for future research projects on HFR will be discussed.

High-order statistical properties of wavefield had been proven to have great influences in the realm of optics. For example, the speckle pattern induced by multi-interference of a coherent light source could be utilized to reconstruct the speckle flowgraphy either in ocular or cerebral blood flow. Such speckle pattern could also be used in depth estimation or optical positioning system. Recently, Kondakci et al. proposed a far-field lensless identification system based on measuring the complex coherence factor (the second-order phenomenon of light) of the field scattering off an obstructive object, which developed another possibility in optical imaging. However, their measurement was based on digital micro-mirror device, which restricted the flexibility of such optical system. Therefore, in this work, we designed an optical system to dynamically measure the complex coherence factor of a Schell-model and quasi-homogeneous beam via spatial light modulator. By analyzing the pixelated structure in theoretically and numerically, it was found that the fill factor of spatial light modulator would not affect the second-order characteristics of incident field even if its first-order characteristics were different. Our experimental results showed this system indeed had a good performance in the measurement of complex coherence factor. We believe the proposed optical system can help the lensless identification. Moreover, this system can be further improved by replacing the reflective-type spatial light modulator with transmitted-type, which will significantly increase the flexibility of optical instrument and will definitely have a great impact on other optical technologies.

We demonstrate a binocular holographic display with an amplitude‐only spatial light modulator (SLM), which enables us to display a 3D scene with much higher frame rate than the case of a conventional stereoscopic 3D. Instead of dividing either frames or pixels for assigning the left and right images, we divide the space near pupils by modulating the phase of a computer generated hologram.

High-speed in-line holography is used to visualize the trajectories fibers which are drawn out in a turbulent flame. In order to improve the SNR, the images are not observed by a conventional reconstruction setup. In our case, the holographic plate is directly placed on the input plane of a wavelet-transform optical system. This processing system is based on a VanderLugt correlator including an Electrically Addressed Spatial Light Modulator (EASLM). The shape of matched filters is deduced by successive rotation and dilatation operations of wavelet functions in the Fourier domain. The 3-D location of a fiber element and its orientation are estimated by searching the daughter wavelet which yields the maximum intensity on the output plane of the correlator, which also contains the reconstructed image. The results are compared with those obtained by a conventional optical reconstruction. The SNR of the images observed on the output plane is improved. Moreover, it is shown that the axis coordinate accuracy is improved to (Delta) z equals plus or minus 50 micrometer, instead of plus or minus 0,5 mm for holographic reconstruction.

Current proposals for Advanced Television for the United States are based upon the premise that temporal and resolution layering are inefficient. These proposals therefore only provide a menu of individual formats from which to select, but each format only encodes and decodes a single resolution and frame rate. In addition, it is being suggested by some people that interlace is required, due to their claimed need to have one thousand lines at high frame rates, but based upon the notion that such images cannot be compressed within the available 18mbits/second. — This paper discusses an approach to image compression which demonstrably achieves thousand line image compression at high frame rates with high quality. It also achieves both temporal and spatial scalability at this resolution at high frame rates within the available 18mbits/second. This technique efficiently encodes 2 MegaPixel images at 72 frames per second, achieving over twice the compression ratio being proposed by ACATS for advanced television. Further, this proposed technique is more robust than the current unlayered ACATS format proposal for advanced television, since all of the bits may be allocated to the lower resolution base layer when stressful image material is encountered. — Thus, a number of key technical attributes are provided by this proposal, allowing substantial improvement over the ACATS proposal. These improvements include: the replacement of numerous resolutions and frame rates with a single layered resolution and frame rate; no need for interlace in order to achieve a thousand lines of two million pixels at high frame rates: and compatibility with computer displays through the use of 72 frames per second.

Charge coupled device(CCD) is one kind of photoelectric solid-state imaging device with excellent performance. It has the features of large array and good image quality. Working under very complex driving timing, it usually has low frame frequency and can not meet the demand of high imaging frame rate. The method of equivalent high frame rate imaging technique is introduced based on normal CCD in this paper. Some CCDs can be drived via electrodes separately. To meet the imaging demands of high frame rate, high resolution and high quality of two frame imaging technique for pulse light images, the right kind of CCDs should be adopted. The most important is that the CCD electrodes must be controlled directly and respectively. The charge transfer period is a key point while designing CCD driving timing for separate pulse light integration, charge package transfer and readout for two pulse light images. The validation experiments for the principle of equivalent high frame rate exposure of two pulse light images has been accomplished. It is shown that two pulse light images with interval of about 2 μs can be distinguished while all CCD’s inherent excellent performance are retained. A kind of two framing camera system with simple structure can be developed based on this principle.

In this paper, we report recent progress that has been made in the development of a high frame rate duplex HF ultrasound system with both B-scan imaging and Doppler flow measurements. A 32-channel HF analog beamformer module with transmitting focusing and dynamic focusing on reception was implemented. High-speed timing circuits were used to achieve high imaging frame rate by reducing the acquisition overhead. Therefore, the frame rate of the system relies only on the field of view. The system also included a 64-channel analog front-end pulser/receiver, a HF pulsed-wave (PW) Doppler module, a PC with a 200MS/s 14-bit PCI A/D card and real-time Labview software for data acquisition and image display. A wire phantom used to evaluate the resolution of the system. High frame rate B-scan images of mouse hearts have been obtained, as well as the PW Doppler blood flow velocity profiles at the specified location. The system is able to acquire real-time B-mode images at a rate greater than 400 frames per second in a 4.8 × 13 mm field of view. In vivo mouse experiment results show a promising future of this system in small animal research. The system will be expanded to support future arrays with more elements.