Vesselin Shaoulov

A mobile head-worn projection display.

A recent advancement was achieved in the integration and miniaturization of a binocular head-worn projection display (HWPD) conceived for fully mobile users. The devised display, referred to as Mobile HWPD (M-HWPD), offers see-through capability through custom-designed, light-weight projection optics and an integrated commercial-off-the-shelf (COTS) retro-reflective screen to display full color stereoscopic rendered images augmenting the real world. Moreover, the light-weight optical device (i.e., approximately 8g per eye) has the ability to project clear images at three different locations within near- or far-field observation depths without loss of image quality. In this paper, we first demonstrate the miniaturization of the optics, the optical performance, and the integration of these components with the retro-reflective screen to produce an M-HWPD prototype. We then show results that demonstrate the feasibility of superimposing computer-generated images on a real outdoor scene with the M-HWPD.

Design and assessment of microlenslet-array relay optics

Recent progress in micro-optics fabrication and optical modeling software opens the opportunity to investigate how microlenslet-array-based compact relay systems can be designed and assessed. We present various optical configurations that include an appropriate baffle computation to eliminate ghost images, followed by an analysis of image quality. The investigation shows the existing trade-off between compactness of the system and a tiling effect observed in the corresponding image, an effect we refer to as lensletization. To yield meaningful optical modeling results, we provide insight into ray-tracing optimization while ensuring a sufficient signal-to-noise ratio. The results show that, given no discernable lensletization, the most compact configuration to image gray-scale images is the 5f-based system. Finally, simulations of the imaging of gray scale and color bitmaps through microlenslet arrays are demonstrated for the first time to our knowledge.

Projection-based head-mounted displays for wearable computers

The projection based head-mounted display (HMD) constitutes a new paradigm in the field of wearable computers. Expanding on our previous projection based HMD, we developed a wearable computer consisting of a pair of miniature projection lenses combined with a beam splitter and miniature displays. Such wearable computer utilizes a novel conceptual design encompassing the integration of phase conjugate material (PCM) packaged inside the HMD. Some of the applications benefiting from this innovative wearable HMD are for government agencies and consumers requiring mobility with a large field-of-view (FOV), and an ultra-light weight headset. The key contribution of this paper is the compact design and mechanical assembly of the mobile HMD.

Compact relay lenses using microlenslet arrays

In an investigation of approaches to compact relay lenses for special effect photography, the potential of microlenslet arrays in image formation is investigated. In this paper, various arrangements of microlenslet arrays and associated baffles are considered and their role on image quality presented. Findings through software simulations clearly demonstrate the trade-offs between image quality and compactness.

Compact microlenslet-array-based magnifier

An ultracompact optical imaging system allowing various magnifications or demagnifications and based on microlenslet arrays is presented for the first time to our knowledge. This research generalizes recent findings regarding microlenslet-array-based 1:1 relay systems [Appl. Opt. 42, 6838 (2003)]. Through optical ray tracing, the feasibility of magnifying gray-scale images through a stack of two dissimilar microlenslet arrays is demonstrated for the first time to our knowledge. Results presented specifically demonstrate that a compact imaging system operating at a magnification of 2 is feasible with an overall length of approximately 9 mm. Optical aberrations of the most basic configuration are evaluated, and optimization is discussed.

Model of wide-angle optical field propagation using scalar diffraction theory

A generalized nonparaxial theoretical framework based on the scalar diffraction theory is developed to describe the propagation of an optical field through a linear optical system with quasi-monochromatic spatially incoherent illumination. Software implementation of this theoretical framework on single and multiple processor platforms was developed and simulated results of the imaging process through optical aberration-corrected optics are presented for both in-focus and out-of-focus imaging, validating the first-order nonparaxial model.

Magnifying miniature displays with microlenslet arrays

Current technology trends are focused on miniaturizing displays, although for specific applications such as the use of head-mounted displays (HMD) this limits the advancements for a wider field-of-view (FOV) and a negligible overall weight of the optics. Due to the advancements of electronics that benefit from smaller miniature displays, universities and companies are focused on developing this technology to meet the growing demand of this global market. Higher resolution displays with added brightness are being developed, but these displays are decreasing in their viewable area. HMDs can benefit from these higher resolution and brighter displays but they will undergo an increased optical weight to compensate for the smaller display size. To overcome this hindrance in HMDs, we demonstrate in this paper how to incorporate microlenslet arrays as an optical relay system to magnify miniature displays. Microlenslet arrays provide respectively shorter focal length which yields a smaller overall object to image distance and an incremental overall weight compared to an otherwise increased optical lens assembly. The contribution of this paper is a patented concept of magnifying/demagnifying miniature displays with microlenslet arrays that can be integrated in a spaced limited area.

Optical phase plates as a creative medium for special effects in images

A new paradigm and methods for special effects in images were recently proposed by artist and movie producer Steven Hylen. Based on these methods, images resembling painting may be formed using optical phase plates. The role of the mathematical and optical properties of the phase plates is studied in the development of these new art forms. Results of custom software as well as ASAP simulations are presented.

Imaging with microlenslet arrays

Recent investigation demonstrated the feasibility of using stacks of microlenslet arrays for optical imaging applications. Many applications driving our research require ultra-compact magnifying imaging systems. In this investigation we demonstrate that a magnifying system based on a stack of two dissimilar microlenslet arrays is feasible.

Investigation of Huygens wavelets in optical imaging

One of the most basic principles of optical wave propagation, Huygens’ principle, was applied to optical imaging of extended objects. Capitalizing on this basic principle, Scalar Diffraction Theory can be applied without the need for any paraxial approximations to describe the propagation of optical fields through an imaging system. In that framework the optical system is considered linear and locally shift-invariant, Furthermore, the object is considered as sum of point sources and the image is obtained as superimposition of the contributions of each point source through the optical system. Most of the current commercially available optical system analysis software is based on approximated models, such as Gaussian beam decomposition, finite-element field propagation, etc. that does not allow for analysis of the most general cases.