In three dimensional display technologies, studies on measuring accommodation and convergence responses to reconstructed images have been reported. However, the physiological characteristics of responses to reconstructed electro-holographic images are not clearly known. In this research, static responses to holographic images and real targets were measured. In addition to measuring responses, tests were conducted to evaluate the depths of reconstructed images in comparison with those of real targets, subjectively. A measurement system consisting of an electro-holographic display, real targets, and an auto refractometer was fabricated to measure accommodation and convergence responses. The display for reconstructing holographic images was a binocular eyepiece - type electro-holographic display based on a Fourier transform optical system. It was confirmed by a camera in which images were located at correct depth and had correct parallax. The target was shaped like a Maltese cross and presented in positions that were 0.5, 1.0, 1.5 and 2.0 diopters from the subjects’ eyes. To avoid the influence of objects except targets, all experimentations were done in a dark room. Regarding the results of the measurements, it was confirmed that accommodation and convergence responses to holographic images varied depending on the position of the targets, and the behaviors of holographic images were similar to those of real targets. In addition, results of subjective evaluation showed that holographic images were recognized at nearly the same positions as real targets. Therefore, subjects were able to perceive holographic images at nearly the same positions as real objects in stereoscopic vision.
Head-mounted type 3-D displays are expected to be useful with Augmented Reality techniques to provide visual
information. However, because these displays use the stereoscopic method to provide 3-D vision, observers
tend to experience eye discomfort when viewing 3-D images due to the disparity between accommodation and
convergence. Electro-holography is a rival technique that displays holograms on electrical devices such as a spatial
light modulator and enables observers to view ideal 3-D images in comfort for many hours. In the current study,
we applied the holography technique to an eyepiece-type display in order to solve the disparity problem. Our
system can represent 3-D images at arbitrary depths and displays large reconstructed images by using a Fourier
transform optical system. We also adopted the time division color method to reconstruct full-color images. In
computer generated holography, holograms for each color are calculated considering with the distance between
their wavelength. In this paper, we describe our calculation algorithm and report the fabrication of an eyepiecetype
full color electro-holographic display for binocular vision. To confirm the effectiveness of the proposed
system, the reconstructed images were evaluated both objectively and subjectively. Results of experiments show
that reconstructed full-color images are located at the correct depth.
In this paper, we propose a method of enlarging the visual field for displaying 3-D images of larger objects at
wide angles. We also theoretically derived a maximum border for the visual field. Because its viewing zone is
close to the lens, we called our method eyepiece-type electro holography. By placing a real image within the
focal point of a convex lens, we obtain a 3-D image of the object as a virtual image behind the lens. The range
of visual field in this case starts on the lens, continues to infinity on the z-axis, and shapes a truncated cone.
There are a lot of three-dimensional (3D) displaying methods such as stereoscopy, integral photography, holography,
etc. These technologies have different 3D vision properties and 3D image qualities. Conventionally,
biological responsiveness is measured by using an actual 3D display in order to evaluate image qualities of 3D
displaying method. It is required quantitative quality measure for 3D images for quantitative evaluation, which
are useful for comparing 3D image quality and a design of a new display system. In this paper, we propose
quality measures for 3D images named volume signal to noise ratio (VSNR), which is a three-dimensionally
extended signal to noise ratio (SNR). A 3D display produces light wave distributions in 3D space, which makes
observers view 3D image illusions. The VSNR measures error of light wave distributions between generated by
actual objects and produced by a 3D display. The light wave distribution is including various factors for 3D
perception of human such as resolution of reconstructed images, visual fields, motion parallax, and depth of field.
The VSNR evaluates these 3D perception factors totally. We were carried out the experiments to certificate the
efficiency of the VSNR. 3D images represented electro-holographic display and integral photographic displays
were evaluated by the VSNR. The results indicated that the electro-holographic display has better quality than
integral photographic display, but speckle noise deteriorates the 3D image quality.
The computerization of the clinical record and the realization of the multimedia have brought improvement of the medical service in medical facilities. It is very important for the patients to obtain comprehensible informed consent. Therefore, the doctor should plainly explain the purpose and the content of the diagnoses and treatments for the patient. We propose and design a Telemedicine Imaging Collaboration System which presents a three dimensional medical image as X-ray CT, MRI with stereoscopic image by using virtual common information space and operating the image from a remote location. This system is composed of two personal computers, two 15 inches stereoscopic parallax barrier type LCD display (LL-151D, Sharp), one 1Gbps router and 1000base LAN cables. The software is composed of a DICOM format data transfer program, an operation program of the images, the communication program between two personal computers and a real time rendering program. Two identical images of 512×768 pixcels are displayed on two stereoscopic LCD display, and both images show an expansion, reduction by mouse operation. This system can offer a comprehensible three-dimensional image of the diseased part. Therefore, the doctor and the patient can easily understand it, depending on their needs.
The influence of binocular stereoscopic (3D) television display on the human eye were compared with one of a 2D display, using human visual function testing and interviews. A 40- inch double lenticular display was used for 2D/3D comparison experiments. Subjects observed the display for 30 minutes at a distance 1.0 m, with a combination of 2D material and one of 3D material. The participants were twelve young adults. Main optometric test with visual function measured were visual acuity, refraction, phoria, near vision point, accommodation etc. The interview consisted of 17 questions. Testing procedures were performed just before watching, just after watching, and forty-five minutes after watching. Changes in visual function are characterized as prolongation of near vision point, decrease of accommodation and increase in phoria. 3D viewing interview results show much more visual fatigue in comparison with 2D results. The conclusions are: 1) change in visual function is larger and visual fatigue is more intense when viewing 3D images. 2) The evaluation method with visual function and interview proved to be very satisfactory for analyzing the influence of stereoscopic display on human eye.