Total Internal Reflection Prism Research Articles

High contrast ratio optimized total internal reflection prism for compact medium-wave IR target simulation system

The existing infrared target simulation system with a total internal reflection (TIR) prism has the problem of low imaging contrast ratio, which will seriously affect the quality of the simulated image. This study proposes a design method of optimized TIR prism (OTIR) based on Snell's law in medium-wave infrared (MWIR) to solve the problem. The radiation theory is used to construct the constraint model of the OTIR prism in the MWIR target simulation system. Further, this study investigates the influence of different states of the digital micromirror device on the beam direction and derives the design equation of the OTIR prism composed of three prisms based on Snell's law. Finally, the designed OTIR prism is simulated and experimentally verified. The simulated results show that the OTIR prism of the compact MWIR target simulation system can enhance the contrast ratio. The experimental results show that the output contrast ratio of the simulation system at 700 K is about 298:1. In the specified temperature range, the contrast ratio of the infrared target simulation system increases with the increase of the light source temperature. Thus, the OTIR prism has the function of improving the contrast ratio of MWIR target simulation system.

Optical system design based on DMD and triple-pass TIR prism for asteroid exploration.

After entering the 21st century, asteroid exploration has become one of the key research directions in the field of deep space exploration. In this article, we present a navigation, imaging, and hyperspectral acquisition integrated optical system designed for asteroid exploration. Based on the pixel-level light modulation capability of the digital micromirror device (DMD), this system introduces a triple-pass total internal reflection (TIR) prism to overcome the limitation of small DMD deflection angles, achieving the co-aperture design of the high-resolution imaging branch and the hyperspectral acquisition branch. In view of the actual usage scenarios, we design a new triple-pass TIR prism and optimize it, correcting the on-axis point coma and astigmatism it introduces, and designing it to be lightweight and compact. Compared to existing optical systems for asteroid exploration, this system offers advantages such as compact structure, no moving parts, high spatial resolution, high spectral resolution, and more flexible imaging modes.

Optical Engine Design for a Compact, High-Luminance DLP Projector Using Four-Channel LEDs and a Total Internal Reflection Prism

How to obtain higher brightness with a small volume projection engine for 4K resolution digital light processing (DLP) is of great significance. In this paper, we first use the fourth channel serving as a blue pump leading to a 52% gain of green brightness. Secondly, a new inline total internal reflection prism glued with a spherical mirror is constructed to notably reduce the length of the relay illumination system by more than 10 mm, resulting in a more compact optical engine with a volume of 210 × 140 × 36 mm3. Thirdly, a projection lens is optimized with a modulation transfer function higher than 0.6 at 93 lines for a distance of 2125 mm with distortion lower than 1%. As a result, the efficiencies of RGB lights are higher than 60%, and the luminance and uniformity on the screen reach 1412 lm and 94.5% measured by the prototype. Our proposed projection system is significantly helpful for designing a compact and high-luminance 4K DLP projection.

Integrated Optical Deformation Measurement with TIR Prism Rods.

In this paper, a novel optical measurement principle for deformation, especially torsion, is presented. A laser beam is guided via total internal reflection (TIR) in a prism rod. Every single reflection causes an increasing change in the beam path, which can be measured by its effect on the outcoupling position of the laser. With a diameter of the prism rod of 10 mm and a length of 120 mm, the system achieves torsion sensitivities between 350 µm/° and more than 7000 µm/°, depending on the actual torsion angle φ. A decency level of sensitivity is defined for comparison, which is exceeded by a factor of ~55 at φ=0. The presented principle of TIR prism rods can be adapted to measure different load cases. Using two laser beams, bending and torsion can be distinguished and combined load cases analyzed. The resulting system can be integrated into machine elements, such as screws, to perform condition monitoring on mechanically loaded components.

ПЕРСПЕКТИВИ ТА ТЕНДЕНЦІЇ РОЗВИТКУ ПРИЛАДІВ ТА МЕТОДІВ НА ОСНОВІ ЯВИЩА ПОВЕРХНЕВОГО ПЛАЗМОННОГО РЕЗОНАНСУ В ІНФРАЧЕРВОНОМУ ДІАПАЗОНІ (ОГЛЯД)

On the phenomenon of surface plasmon resonance (SPR) and its use for the study of gaseous and liquid substances, more and more papers are published in professional journals. These studies are used in clinical diagnostics, food industry, environmental monitoring. The advantages of SPR sensors include quick results, a small amount of analyte, the possibility of real-time measurement of such reactions as antigen-antibody, protein-protein, enzyme-substrate or inhibitor, protein-DNA, receptor-drug, protein-polysaccharide , virus protein and reactions of external stimulation of a living cell. The high sensitivity of the method is due to the properties of its resonant nature of plasmon-polariton oscillation. SPR devices are used in laboratory conditions and there is a potential possibility of further reduction of overall dimensions for use in field conditions. The use of SPR in the IR region of the spectrum has a number of advantages, namely: the laser light penetrates deeper into the sample, it becomes possible to study substances that are not transparent in the visible region, but transparent in the infrared, which allows working with larger research objects, provides a narrower characteristic of the SPR, which allows to more accurately determine the angle of the minimum of the SPR, and also requires the application of a thinner layer of gold on the glass chip, which reduces the cost of the analysis. The review analyzed literary sources and determined prospects for the development of devices and methods based on IR SPR, considered prospective materials of the sensitive element and prisms of the total internal reflection device according to the Kretchman scheme. It was determined that, in addition to precious metals (gold and silver), conductive metal oxides ITO, ZnO, CdO:Dy have the prospect of being used as materials for manufacturing the sensitive element of the sensor. Their compliance with the requirements for materials for maintaining the SPR was analyzed. It is shown that CdO:Dy has the greatest potential due to sufficient mobility and density of charge carriers. But in practice, the most common use is gold and silver, for which it is necessary to determine the optimal thicknesses for the IR range of SPR. Total internal reflection prisms (hereafter prisms) in SPR devices according to the Kretchman scheme are usually made of glass, but for the IR range it is advisable to consider other materials that are less sensitive to the temperature effect of the IR laser. The paper analyzes the dependence of the plasmon resonance parameters on the prism material. The possibility of using not only different brands of traditional glass, but also glass ceramics with practically zero coefficient of thermal expansion, semiconductor silicon and chalcogenide glass for the manufacture of prisms is shown.

Single-prism polarizer for laser emission with higher power

Subject of study. The properties of a new prismatic polarizer-analyzer of laser (optical) emission with higher power were investigated. The polarizer was designed based on a birefringent crystal in the form of a single total internal reflection prism with a triangular cross-section. Spectral dependences of the geometry of the cross-section in the refraction plane were investigated for two selected polarizer materials. Aim. The study was aimed at designing a polarizer in the form of an individual single-element device capable of functioning in the laser beams with higher power that maintains the original direction of radiation propagation with minimum optical losses and without anamorphosis of the beam cross-section. Method. The transmission of radiation through an optically anisotropic crystalline prism with an arbitrary triangular cross-section was investigated using mathematical modeling. Snell’s equations, which were developed for refraction and total internal reflection of radiation on the faces of an anisotropic prism, were used. Based on the obtained solutions, the spectral dependences of angular structural parameters of prismatic polarizers were calculated under conditions of maintaining the collinearity of the input and output rays and their refractions on the input and output faces fixed at Brewster’s angles. The energy losses and spectral ranges of operation of prismatic polarizers composed of two selected crystalline materials with a priori defined geometry were analyzed. Main results. A new prismatic polarizer was designed and investigated. Its main feature corresponds to anisotropic total internal reflection of optical radiation from one of the faces of a birefringent single prism under Brewster’s refractions on the input and output faces. We established that the device exhibits minimum optical losses, collinearity (or coaxiality) of unpolarized and polarized beams, and no anamorphotic distortion of the cross-section of the output p-polarized beam. Furthermore, we demonstrated that in the case of virtually symmetric prisms for which the difference between the structural angles and Brewster’s angles is 3°–7°, the effect of anamorphism of the beam cross-section is negligibly small. The spectral ranges of the device operation were determined for several specific designs. A weak dependence of spectral bands on the selected orientations of the polarizer crystal was observed. It manifests in the symmetry of the obtained dependences. We demonstrated that the prisms composed of YVO4 crystals are the most advantageous for obtaining the widest spectral bands in the near- and mid-infrared spectral ranges. Angular tolerances for the divergence of the incident beams were determined based on analysis of the angular deviations of the incidence angles from the Brewster’s angles. The device can also be used in observational optics as an anisotropic equivalent of the isotropic Dove prism. The difference between the proposed device and the Dove prism is the fact that the proposed device provides the potential of observing an image in ideally linearly polarized light. Practical significance. The proposed single-element design of a prismatic polarizer with Brewster’s input and output faces enables the use of the device for polarization (or polarization analysis) of laser beams with power higher than the values for which the standard multicomponent polarizers are applicable.

Thermal model of a photovoltaic module with heat-protective film

Research on reducing the working temperature of PV modules is gaining attention to improve their electrical performance, efficiency, and life especially in warm climatic conditions. This study describes the use of novel heat-protective film based on holographic coating with a total internal reflection prism layer applied to maintain the operating temperature of the photovoltaic module. A mathematical model of thermal protection based on the holographic film is described. MATLAB/Simulink simulation was used to estimate the current-voltage and output power–solar irradiance characteristics of a photovoltaic module with and without holographic film. Regression models were developed based on field testing to determine a relationship between the temperature of heat-protected/unprotected PV panels and ambient temperature. The results showed that a temperature reduction of 3.54 °C is obtained for solar modules with thermal protection film compared to the one without holographic film. The modeling and field performance results confirm the effectiveness of the thermal protective film in reducing the temperature and improving the photovoltaic panel performance in hot climates.

High-contrast ratio and high-efficiency anamorphic DLP illumination system design with a freeform surface lens.

In this paper, an anamorphic digital light processing illumination system design with a freeform surface lens is described. A lens with a freeform surface lens is combined with the achromatic total internal reflection prism set for application in a relay lens system. In order to achieve a high contrast ratio without sacrificing illumination system efficiency, the novel, to the best of our knowledge, design uses an x-y polynomial surface for the freeform surface lens to reduce the overlap angle of the anamorphic angular distribution in angular space. Moreover, there is no need to use a baffle at the aperture stop in this novel design. We can reach a half-cone angle of 17.49° in the y direction of the angular distribution in angular space. The overlap angle is only 0.98°. Finally, with this novel design, we can achieve a high contrast ratio of 9128:1 and an illumination system efficiency is 66.4%. The four-corner average spot size at the active area of the digital micromirror device chip is controlled at about 240 µm, and the optical distortion is less than 1%. The corresponding lateral color aberration is 3.61 µm.

Three-zone multifocus hybrid Fresnel lens concentrator.

In this paper, we designed a three-zone multifocus hybrid Fresnel lens concentrator without a homogenizer. This concentrator uses three types of prisms: a refractive prism, a single total internal reflection (STIR) prism, and a double TIR (DTIR) prism. In order to achieve a uniform irradiance distribution, the Fresnel lens is cut into four quadrants and reconnected. Moreover, by decreasing the angle of the edge ray, the hot spot effects caused by the STIR and DTIR prisms can be reduced. Finally, the three-zone multifocus hybrid Fresnel lens concentrator can achieve a geometric concentration ratio of 2121X, f-number of 0.441, optical efficiency of 76.570%, acceptance angle of ±0.268∘, uniformity of 57.002%, and hot spot criteria of 1.369.

Designing an anamorphic illumination system with an RTIR prism for a tilt-and-roll-pixel-type projector.

A relay lens system design for a mini-projector with telecentric illumination is described. The reverse total internal reflection (RTIR) prism for angular magnification and lateral magnification is discussed in detail, and magnifications under different digital micromirror devices (DMD) are compared. The tilt-and-roll pixel (TRP) DMD chip (tilt angle is ${\pm 17}^\circ $±17∘) is the latest spatial light modulator, and the f-number of the illumination system is 1.71. Using the TRP DMD, the lateral magnification and the angular magnification for the RTIR prism can be increased by 3.77% and 8.73% over that obtainable using the conventional DMD chip (tilt angle is ${\pm 12}^\circ $±12∘). In order to solve for the angular magnification of an RTIR prism, the baffle is set at the aperture stop of the relay lens system. There is a trade-off between the efficiency and the contrast ratio with the baffle. When B (the position of the baffle) is at 0.11, the contrast ratio of the illumination system is 7590:1 and the efficiency is 57%. The spot size at the edge and corner of the DMD active area is controlled to be less than 250 µm, and the optical distortion is less than 1%.

Towards simultaneous observation of path and interference of a single photon in a modified Mach–Zehnder interferometer

Classical wisdom of wave–particle duality regulates that a quantum object shows either the particle or wave nature but never both. Consequently, it would be impossible to observe simultaneously the complete wave and particle nature of the quantum object. Mathematically the principle requests that the interference visibility V and which-path distinguishability D satisfy an orthodox limit of V 2 + D 2 ≤ 1 . The present work reports a new wave–particle duality test experiment using single photons in a modified Mach–Zehnder interferometer to demonstrate the possibility of breaking the limit. The key element of the interferometer is a weakly scattering total internal reflection prism surface, which exhibits a pronounced single-photon interference with a visibility of up to 0.97 and simultaneously provides a path distinguishability of 0.83. Apparently, the result of V 2 + D 2 ≈ 1.63 exceeds the orthodox limit set by the classical principle of wave–particle duality for single photons. We expect that more delicate experiments in the future should be able to demonstrate the ultimate limit of V 2 + D 2 ≈ 2 and shed new light on the foundations of contemporary quantum mechanics.

Tunable-illumination for laser Fourier ptychographic microscopy based on a background noise-reducing system

It is inherently difficult for a conventional microscopic imaging system to produce images with both wide field of view (FOV) and high-resolution because of its limited space bandwidth product. Fourier ptychographic microscopy (FPM) has been developed to overcome this limitation by using angle-varied illumination to enhance the performance of the system. In this paper, we propose a FPM imaging approach that employs a laser source with a newly developed illumination control optical system. The proposed system consists of a digital micromirror device and a zoom system with a condenser lens to provide sample illumination with angle-varied pattern directions and controllable pattern sizes. In addition, a total internal reflection prism is employed in the system to remove unexpected background noise and extend the FOV for reconstruction. The proposed system is validated against a USAF resolution target and a biological sample, and as a result reconstructs images with higher resolution and more details once the positional misalignment correction algorithm is employed. We envision that the proposed FPM system will be suitable for high-speed imaging applications.

Achromatic Total Internal Reflection Prism in DLP Projection System

Achromatic Total Internal Reflection Prism in DLP Projection System

Achromatic Total Internal Reflection Prism in DLP Projection System

Achromatic Total Internal Reflection Prism in DLP Projection System

High Field-of-View Near-Eye Display Using Total Internal Reflection Prism and Holographic Printing Technique

High Field-of-View Near-Eye Display Using Total Internal Reflection Prism and Holographic Printing Technique

High Field-of-View Near-Eye Display Using Total Internal Reflection Prism and Holographic Printing Technique

High Field-of-View Near-Eye Display Using Total Internal Reflection Prism and Holographic Printing Technique

Mathematical Analysis of Nonimaging Fresnel Lenses Using Refractive and Total Internal Reflection Prisms for Sunlight Concentration

During the design of nonimaging Fresnel lenses, the reflectance losses at the refracting surfaces should be taken into account because, depending on the parameters of each prism, semiacceptance angle θin and output angle θout, these losses can decrease the total efficiency of the lens. On this subject, an analysis and comparison between a Fresnel lens composed only of refractive prisms and others with total internal reflection (TIR) prisms are presented and, using this information, a design method of hybrid Fresnel lenses composed of refractive and TIR prisms is proposed to reduce reflectance losses from the surface. The work presents the radiance profile and transmittance for a Fresnel lens of each type, to compare its advantages and disadvantages providing an alternative for the design and construction of nonimaging Fresnel lenses according to optical devices requirements.

Global solution of achromatic Total Internal Reflection prism in projection system

Abstract In this paper, an achromatic total internal reflection (TIR) prism set, consisting of two stacked prisms, is designed to reduce the lateral color aberration of a mini projector with light-emitting-diode (LED) light sources. Two different types of the prism set are proposed. Type 1 prism set is the first prism with a small Abbe number material stacked with the second prism with a large Abbe number material. By analyzing the optical properties of the proposed ATIR prism sets, we are able to choose an appropriate optical material combination of the prism set. For type 1 prism set, the corresponding lateral color aberration is 0. 65 μ m and the size is 2306 mm3. Nevertheless, the type 1 suffers from efficiency loss of 15.5%. For type 2 prism set, the corresponding lateral color aberration is 0. 61 μ m and the compact prism size is 3000 mm3. Although the size of type 2 prism set is larger than that of type 1, the efficiency loss can be as low as 1 %.

An ultrashort throw ratio projection lens design based on a catadioptric structure

In this paper, we present a rotational symmetry for an ultrashort throw (UST) lens with offset field. The UST lens has a throw ratio of 0.23 and a total track of 195 mm. The optical elements of the UST lens are comprised of two parts. First, a catadioptric projection lens where the catadioptric function permits reaching an ultrashort throw ratio, short total track, while at the same time requiring fewer lens elements. The second part is a collimating lens which takes advantage of the telecentric condition to generate uniform total internal reflection (TIR) in the TIR prism. With this design, an effective focal length of -1.96 mm and a f-number of 2.4 can be obtained. The root mean square spot size and lateral colour of all fields are smaller than one pixel in size. The maximum optical distortion of −0.97% and TV distortion of 0.2% are acceptable. In terms of image quality, the modulation transfer function (MTF) values for all fields are above 0.65 at 0.245 line pairs/mm. Even when the tolerance error is considered, the MTF values for all fields are still above 0.3. The suitability of the novel UST lens design for projection applications is discussed.

Measurement of small wavelength shifts based on total internal reflection heterodyne interferometry

This Letter presents a method of an optical sensor for measuring wavelength shifts. The system consists of a diffraction grating and a total internal reflection heterodyne interferometer. As a heterodyne light beam strikes a grating, the first-order diffraction beam is generated. The light penetrates into a total internal reflection prism at an angle larger than the critical angle. A wavelength variation will affect the diffractive angle of the first-order beam, thus inducing a phase difference variation of the light beam emerging from the total internal reflections inside the trapezoid prism. Both the experimental and theoretical results reveal that, for the first-order diffractive beam, the sensitivity and resolution levels are superior to 5°/nm and 0.006 nm, respectively, in the range of wavelength from 632 to 634 nm, and are superior to 3.1°/nm and 0.0095 nm in the range from 632 to 637 nm. For the theoretical simulation of the fourth-order diffractive beam, they are superior to 6.4 deg/nm and 0.0047 nm in the range from 632 to 637 nm.