Wen-Shing Sun

Simulating the illuminance and the efficiency of the LED and fluorescent lights used in indoor lighting design

In this study we simulate the illuminance and efficiency of four different types of reflector LED and fluorescent light sources for interior illumination. According to our calculation results of the examination of simulations and real situations, we find that the LEDs do perform better than fluorescent lights. We also consider the problems of glare with LED lights by utilizing a diffuser to protect the eyes. We are assured of the potential advantages of LED lighting in the future.

Hybrid sunlight/LED illumination and renewable solar energy saving concepts for indoor lighting

A hybrid method for using sunlight and light-emitting diode (LED) illumination powered by renewable solar energy for indoor lighting is simulated and presented in this study. We can illuminate an indoor space and collect the solar energy using an optical switching system. When the system is turned off, the full spectrum of the sunlight is concentrated by a concentrator, to be absorbed by solar photovoltaic devices that provide the electricity to power the LEDs. When the system is turned on, the sunlight collected by the concentrator is split into visible and non-visible rays by a beam splitter. The visible rays pass through the light guide into a light box where it is mixed with LED light to ultimately provide uniform illumination by a diffuser. The non-visible rays are absorbed by the solar photovoltaic devices to provide electrical power for the LEDs. Simulation results show that the efficiency of the hybrid sunlight/LED illumination with the renewable solar energy saving design is better than that of LED and traditional lighting systems.

Portable digital micromirror device projector using a prism

A newly designed ultrasmall total internal reflection prism with a size of 29 mm x 22 mm x 24 mm and weight of 19.5 g is proposed for use in a pocket-sized Digital Micromirror Device projector. The entire projector, including an arc lamp illumination, relay, and projection system, has a height of 48 mm and a footprint of 80 mm x 132 mm. By using an overdriving f/2.0 projection lens, the geometric efficiency of the projection system, eta(geo-pro), can be enhanced from 80% to 92%. Although, at the same time, the contrast decreased from 1200:1 to 500:1, this can be enhanced using an off-axis stop. By tuning the position of the stop, the contrast can be as high as 3700:1 for a eta(geo-pro) equal to 90%. Using what we believe to be a novel prism design, we can get a very compact optical system with a high efficiency and good contrast ratio.

Integration of Non-Lambertian LED and Reflective Optical Element as Efficient Street Lamp

A cost effective, high throughput, and high yield method for the increase of street lamp potency was proposed in this paper. We integrated the imprinting technology and the reflective optical element to obtain a street lamp with high illumination efficiency and without glare effect. The imprinting technique can increase the light extraction efficiency and modulate the intensity distribution in the chip level. The non-Lambertian light source was achieved by using imprinting technique. The compact reflective optical element was added to efficiently suppress the emitting light intensity with small emitting angle for the uniform of illumination intensity and excluded the light with high emitting angle for the prevention of glare. Compared to the conventional street lamp, the novel design has 40% enhancement in illumination intensity, the uniform illumination and the glare effect elimination.

Determination of the mechanical properties of thin films by digital phase shifting interferometry

A new method for the measurement of internal stress and coefficient of thermal expansion of thin oxide films is presented and investigated experimentally, that combines digital phase shifting interferometry with image-processing technique to improve the accuracy of the conventional interferometric method. The change of the deflection (or curvature) of the coated substrates by the deposited film can be obtained by the phase maps. Using the Zernike polynomial fitting algorithm, a 3-D contour plot is generated from the polynomial coefficients to visualize the deformation of the thin film. Four oxide films prepared by ion beam sputter deposition with a Kaufman-type ion source are investigated for their mechanical properties. The contribution of the proposed method is to increase the sensitivity and accuracy of the temperature-dependence stress measurements.

Ophthalmic lens design with the optimization of the aspherical coefficients

An efficient approach for the designing of ophthalmic lenses, based on the optimization of the aspherical surface coefficients is presented. We show that five optimization constraints are enough to both reduce the aberrations and prevent the development of inflection points along the aspherical surface. In particular, we solve the inflection point problem by counting the second derivative of the sag with respect to the height of the aspherical surface as one of the constraints. The design data indicate that nonconicoidal aspheric lenses can be made thinner and flatter than the equivalent spherical or conicoidal lenses. The traditional damped least-squares methods are used and design results are given for both aspherical negative lenses and aspherical positive lenses.

Dual view capsule endoscopic lens design

A dual view capsule endoscopic (DVCE) lens is proposed with front view and back view functions. This is a hybrid lens with a catadioptric mirror and an aspherical surface to support both view functions. The field of view (FOV) for the front view function is 90 degrees. The FOV for the back view function is 260 to 290 degrees. The TV distortion for the front view and back view function is under 30% and 25%. The corner relative illuminations for the two view functions are above 0.53. The Modulation Transfer Function (MTF) performance at the Nyquist Frequency for the two view functions can be kept above 0.35, even under tolerance they can remain above 0.2. Moreover, the telecentric conditions at the image plane of the DVCE system can support constant magnification through focusing. This condition can reduce the measurement error by slightly defocusing of the lens. Thus, the two view functions can offer physicians a wide viewing angle to deal with lesions over the fold.

Laser expander design of highly efficient Blu-ray disc pickup head

We present a collimator design with a horizontal beam expander for a Blu-ray Disc pickup head. The design transforms the shape of a laser diode beam from an elliptical into circular which achieves higher efficiency in the pickup head system. In this research, we suggest two ways to do the beam expander. One way is to use two cylindrical lenses, and the other is to use two prisms.

Design of miniature HD–DVD optical pick-up head using a Penta prism

A novel design of HD–DVD optical pick-up head is proposed. The geometrical size of the pick-up head is reduced by using a combined system of a Penta prism and an aspherical lens. Such a combined system can replace the mirror and collimating lens in a conventional pick-up head, to achieve a miniature HD–DVD pick-up head.

Simulation design of a wearable see-through retinal projector

This study proposes a new simulation design for a wearable see-through retinal projector combined with a compact camera. The see-through retinal projector is composed of an illumination system and eyepiece system. In this eyeglass-mounted design, all the information is projected directly into the users eyes using a see-through retinal projector. The retinal projector forms a 20 in. (50.8 cm) upright virtual image located 2 m in front of the human eye, and the illumination system provides uniform illumination for liquid crystal on silicon (LCoS) panels. Moreover, an RGB LED array is used as the light source to generate color images with color sequences. The compact camera has a lens with an aperture of F/2.8, a half field-of-view (FOV) of 30°, and 2 million pixels. This optical system design with the combination of a see-through retinal projector and a compact camera has a volume of about 5.83 cm(3) and a weight of 6.02 g.