Non-imaging Optical System Research Articles

Large dynamic range stellar radiation simulation optical system

For the current stellar spectral simulation can not realize the stellar color temperature information with large dynamic range simulation, this paper proposes a broad spectrum high-resolution subdivision and spatial beam zoning modulation combined with a large dynamic range of stellar radiation information simulation method, designed a kind of imaging and non-imaging stellar radiation information simulation optical system, using an optical system to achieve multi-color temperature spectrum and large dynamic range stellar simulation. The experimental results show that the designed system can simultaneously achieve the spectral simulation accuracy (single point evaluation) better than ± 7% in the range of spectral 450–1000 nm and color temperature 3000–11,000 K; on the premise of ensuring the spectral simulation accuracy, the magnitude simulation range reaches 0 to + 12 Mv, and the magnitude simulation accuracy is better than ± 0.05 Mv; Accurate simulation of stellar spectral information and energy large dynamic range tuning is realized, and the system is extended. The system function has been extended to realize the switching of broadband and narrowband modes, The half-peak width of the narrowband output beam is better than 4.1 nm, which extends the application of the spectral simulation technology and provides the theoretical and technical basis for the ground calibration of the development of the high-precision stellar radiation information ground simulation system.

Computational analysis and optimization of daylight collector geometry for removal of hotspots in circular mirror light pipe

The illuminance patterns formed on the various surfaces of a tubular daylight guidance system (TDGS) were numerically measured and calculated for the beam sunlight input. For this study, the TDGS comprises a revolved parabolic profiled daylight collector geometry and a vertical MLP system for daylight guidance. TDGS is basically a non-imaging optical system that is designed to efficiently transmit available sunlight across the MLP (mirror light pipe) length. But while doing so the problematic hotspots are observed mainly on the diffuser placed at the exit aperture of cylindrical MLP which further results in non-uniform illumination in the daylit room. In this work, the use of a prismatic casing arranged sideways to the parabolic profiled collector and a sloped diffuser as a top cover shows a significant reduction in the hotspot problem on the exit aperture of MLP without compromising light transmission in TDGS. The ‘non-uniformity’ index value, Ir signifying the ratio of maximum illuminance to average illuminance on the diffuser surface dropped considerably for the proposed design signifying an increase in uniformity on the exit aperture of MLP. For 1 m long MLP (aspect ratio = 2.5), the maximum value of Ir was ∼ 19 and ∼ 37 for TDGS with dome collector and TDGS with parabolic collector having plane cover (TSA) respectively on midday timings of 21st June while for the proposed design the value was Ir < 5. For 2 m long MLP (aspect ratio = 5), the value was Ir < 4 much lower in comparison to Ir of ∼ 20 and ∼ 36 for TS with dome collector and TSA respectively. A considerable decrease in the severity of hotspots was realized from the results. The proposed collector design was also tested for the illuminance values on the work plane of the simulated room under beam sunlight, diffuse skylight, and overcast sky conditions. No compromise in the average illuminance values was observed when compared to the parabolic collector with transparent casing. Moreover, the proposed design gave enhanced values of illuminance under low altitude beam sunlight as well as under diffuse skylight for various timings of the day. Performance under the overcast sky was found slightly lesser in comparison to conventional collector designs though nominal levels of illuminance were observed for all the configurations of collectors due to the very less magnitude of light availability.

Design of non-imaging receiving system for large field of view lidar

Lidar has been widely used in many fields due to its high precision. The system must also have a corresponding large field of view receiving capability in order to achieve effective detection of targets when imaging lidar realizes large-angle scanning. For the InGaAs-APD detector component, there is a contradiction between the high-frequency response bandwidth and the size of the photosensitive surface. This paper proposes a large surface four-quadrant InGaAs-APD detector with 2 × 2 area array structure design, which based on a small photosensitive panel detector with a unit diameter of 0.5 mm. On the basis of ensuring the cut-off frequency bandwidth of 100 MHz, it also realizes signal reception with large field of view and high sensitivity. For the receiving lens of the system, the relationship between the bin size of the detector and the receiving field of view in the non-imaging optical receiving system is studied. Under the condition that the parameters such as the size of the detector facet have been determined, the best position of the detector is optimally designed to maximize the receiving field of view. Based on theoretical foundations such as radiation angle coefficient and etendue, the non-imaging optical system lidar distance equation is established to evaluate the light-gathering ability of receiving lenses with different effective apertures and focal lengths, and to optimize optical structural parameters such as the best effective aperture and focal length of the receiving lens. Finally, the aspheric lens with the best parameters is selected as the basic receiving optical lens of the system, and an array type large field of view direct detection technology is proposed. The receiving optical system is composed of 6 aspheric single lenses, and the structure is in the form of 2 × 3 array, which finally realizes the efficient detection of echo signals with a large field of view of 48° × 26°.

Realization of translation group in optical design with deep nerual network under eikonal-energy mapping

&lt;sec&gt;Nonimaging optical design aiming at energy control has wide applications in optoelectronics. A nonimaging optical system is composed of a light source, optical components, and a target screen, and can be described by an equation named light taming equation(LTE). Given the light source and prescribed target spot, the required freeform surfaces of the optical component can be obtained by solving the LTE. If the light source profile does not change, the optical surface will make some suitable morphs when the target spot translates on the screen, and these morph operators can well be described by the group theory.&lt;/sec&gt;&lt;sec&gt;The basic LTE is established for a normal nonimaging optical system, which is to design an optical element for redirecting the light from the source so that a prescribed light distribution is generated on a given target. A translation light taming equation(T-LTE) is derived for the case of only spot translating on the target screen, and an optical translation group(OTG) is introduced for describing all of the morph operators of the optical surface caused by light spot translation. There are multiple solutions for the same T-LTE, but the uniqueness of the T-LTE solution is necessary for OTG. Fortunately, the eikonal-energy(KE) mapping method can guarantee the uniqueness of the T-LTE solution, where K is the optical path length. The supporting quadric method(SQM) is one of the KE mapping methods when the nonimaging optical system has only one optical surface to be resolved. The LTE with SQM is deduced, and the OTG can be discussed in K-space. A deep neural network(DNN) is introduced to fit the KE mapping and spot translating operators to obtain the required optical surface. Taking the uniform square spot for example, the SQM generates the sample data of spot translation to train the DNN. The optical simulation results show that the error between the light distribution generated by the DNN and the standard uniform square spot is small, all on the order of 10&lt;sup&gt;−3&lt;/sup&gt;, which indicates that the DNN and KE mapping method have successfully realized the function of the OTG. The results are of guiding significance in implementing the intelligent nonimaging optical design.&lt;/sec&gt;

Design and performance analysis of high efficiency non-imaging concentrated optical system

Aiming at the low optical efficiency of Fresnel lens, a high-efficiency non-imaging concentrated optical (NICO) system composed of an aspheric lens and a trumpet lens was designed. The aspheric lens was optimized in sequential mode of Zemax, and the geometric radius of its image spot was reduced from 42 mm to 1.7 mm by minimizing the spherical aberration. The aspheric lens and trumpet lens were modeled and optimized in non-sequential mode of Zemax, and the NICO system with 87% optical efficiency and 0.9° received angle was achieved by Monte Carlo ray tracing analysis. Finally, the packaging and testing of the high concentrated photovoltaic (HCPV) module were completed based on samples of an aspheric lens array and 48 trumpet lenses. The test results showed that the photoelectric conversion efficiency of the module reached 30.03%, which was significantly improved compared with the HCPV module composed of the Fresnel lens.

Ornamental fish counting by non-imaging optical system for real-time applications

One of the more labor-intensive operations in ornamental fish farms is fish counting. It is performed primarily when spawned fry are collected and introduced into grow-out tanks and when preparing fish for marketing. For various reasons such as cost and mode of operation of existing counting systems and inability to combine them with existing farm equipment, in many farms fish are counted manually despite time pressure and shortage of labor. An optical system for fish counting has been developed using hybrid non-imaging optics and an image-processing scheme to obtain an efficient single-detector counting system. The optical design includes a tailored field-stop aperture and a non-imaging scheme that reduces the influence of water fluctuations in a partially filled tube. The resultant increased signal-to-noise ratio enables overcoming the effects of water fluctuations. A prototype was tested with dummy and live fish. Counting errors with well-separated fish were less than 2%. Such a system can be used in similar operations with other small fish (e.g. edible fish hatcheries).

A non-imaging optical system for characterisation of ball-shaped micro-indenters

To quantitatively determine the tip radius of spherical/conical and Rockwell micro-indenters, a practical tip radius measurement system is presented. Realization of the optical system has been detailed, including its theoretical and actual resolution and error sources. For the purpose of experimental investigation of the performance of the non-imaging radius measurement system, a sapphire sphere with a nominal radius of 200μm has been measured. Detailed data analysis indicates that higher-order form deviation of the object under test might be one of the key error sources within the calibration setup. Further experiments indicate that the prototype of the non-imaging system is able to measure real conical and Rockwell indenters with adequate resolution.

Ray tracing method in phase space for two-dimensional optical systems.

Ray tracing is a forward method to calculate the photometric variables at the target of a non-imaging optical system. In this paper, a new ray tracing technique is presented to improve the accuracy and to reduce the computational time of the classical ray tracing approach. The method is based on the phase space representation of the source and the target of the optical system, and it is applied to a two-dimensional TIR-collimator. The strength of the method lies in tracing fewer rays through the system. Only rays that lie in the meridional plane are considered. A procedure that disregards rays in smooth regions in phase space, where the luminance is continuous, is implemented and only the rays close to discontinuities are traced. The efficiency of the method is demonstrated by numerical simulations that compare the new method with Monte Carlo ray tracing. The results show that the phase space approach is faster and more accurate than the already existing ray tracing method; moreover the phase space method converges as one over the number of rays traced unlike Monte Carlo ray tracing in which the speed of convergence is proportional to one over the square root of the number of rays.

Special aspects of initial optical scheme selection for design of non-imaging optical systems

Subject of Research. The research results, structural composition analysis and the parametric synthesis of the projected imaging and non-imaging optical systems were presented. We made an attempt to use the gained experience about imaging systems while designing non-imaging systems, by adapting the composition theory for the calculations of non-imaging systems. Several patterns were revealed, which provide a deeper understanding of the design process of non-imaging optical systems; measures of its optimization were proposed. Method. We investigated the applicability of the theory of composition and synthesis of non-imaging optical systems. The main provisions of the theory of composition are based on the division of all available optical elements in four types depending on their functionality, which corresponds to a modular design. Similar items were identified in non-imaging optical systems and adaptation of composition theory to their design became possible. Main Results. General design patterns of imaging and non-imaging optical systems were studied. Classification of systems, components, as well as technical and generic characteristics of imaging and non-imaging optical systems was determined. Search mechanism of the initial optical system by means of structural and parametric synthesis of non-imaging optical system was formalized. The basic elements were determined included in non-imaging systems and their classification by functionality was done. They were subdivided into basic, corrective, wide angle and high aperture ones. The rules for formation of these elements and their composition were determined: surface reflecting, refracting, spherical and nonspherical elements with total internal reflection. The foundations of composition theory for non-imaging optical systems were laid. The approbation of this method was carried out on the example of the illumination system calculation for surgical room. A 3D model of an illumination optical system for surgical room was obtained, consisting of three identical domes. The illuminator designed with the use of the proposed methodology showed high energy efficiency (92.3%). Practical Relevance. The results can find application in optical design of non-imaging systems having various functionality, for example, illuminators, concentrators, etc. and can provide import substitution of similar foreign devices. The results can be useful by engineers specializing in the design and/or operation of non-imaging optical systems.

Construction principle of a nonimaging optical system of an illuminating device

It is shown that, if (like the point-spread function in imaging optics), the relative brightness distribution in a radiation source of finite size is taken as the nonimaging display function, the actual surface-illuminance distribution is determined by the integral of the convolution of the nonimaging display function with the surface-illuminance distribution by a point source. This paper discusses the use of a reflecting surface to equalize the surface illuminance, irrespective of its imaging properties.

Measurement technique of telecentricity for the illumination system in the 193 nm photolithography

The location of mask and wafer for the photolithography is one of the important and precise parts in a lithographic test pattern. If mask and wafer are illuminated obliquely (that is to say telecentricity) by incident light, the diffracted waves will occur asymmetrically. If such an asymmetry is relatively large in the illuminate system, which makes the illuminate system no longer a telecentric system, the non-imaging optical system becomes imaging optical system, and the projection lithography will be meaningless. Therefore, in this paper we propose a measurement method of telecentricity for lithographic test pattern and investigate the influences of various factors on the imaging properties by numerical simulation. Telecentricity measurement can be performed using a pinhole that comprises 40×40 point under the different illumination system (conventional and dipole) in the wafer plane. We show measurement values and measurement errors of telecentricity for illumination system (conventional and dipole). The results indicate that measurement values and measurement errors of telecentricity satisfy the measurement requirement from our method in the wafer plane.

LCD 디스플레이용 색채계 렌즈에 관한 비결상 광학설계

본 논문에서는 LCD 디스플레이용 색채계 렌즈에 관해 근축광학적인 방법에 의한 비결상 광학설계를 소개한다. 색채계란 디스플레이 상의 측정영역으로부터 방출된 광을 빛의 3원색인 빨강, 녹색, 초록으로 분해하는 측정기기로써, 결상렌즈가 아닌 집광렌즈를 필요로 한다. 집광렌즈는 비결상 렌즈이고 측정영역과 감지영역 간의 특정한 압축비 조건을 만족해야 한다. 총체적인 비결상 광학조건을 이해하기 위해, 근축광학을 사용하여 필요충분조건을 해석적인 표현식으로 유도하였고, 나아가 간단한 공식으로 발전시켰다. 이 공식의 타당성은 CODE V와 Light-Tools를 사용하여 검증하였다. 이 공식은 색채계용 집광렌즈 뿐만 아니라, 레이저 빔의 세기를 균일하게 만들기 위한 어레이 렌즈의 설계에도 유용하게 확장 적용될 수 있다. We introduce Gaussian (or paraxial) optics that can be successfully applied to design, for use in a color analyzer, a non-imaging optical system on a measurement probe for LCD display. The color analyzer is used to decompose colored lights leaving from some measurement area on the LCD display to red, green, and blue. The color analyzer must include a condenser lens whose purpose is to gather colored lights to illuminate a small area on the sensor. In order to satisfy a reduction ratio between the measurement area and the sensing area with a non-imaging condition, a condenser lens is analytically treated by means of Gaussian optics so that good understanding of the non-imaging condenser lens is achieved as a good design is derived. As a result, the technique shows the necessity of analytical treatment in contrast to the design approach using only commercial software such as CODE-V, Light-Tools, and others. Of course, CODE V and Light-Tools are also utilized in this paper to confirm and complete the Gaussian optical design.

High data rate multiple input multiple output (MIMO) optical wireless communications using white led lighting

Solid-state lighting is a rapidly growing area of research and applications, due to the reliability and predicted high efficiency of these devices. The white LED sources that are typically used for general illumination can also be used for data transmission, and Visible Light Communications (VLC) is a rapidly growing area of research. One of the key challenges is the limited modulation bandwidth of sources, typically several MHz. However, as a room or coverage space would typically be illuminated by an array of LEDs there is the potential for parallel data transmission, and using optical MIMO techniques is potentially attractive for achieving high data rates. In this paper we investigate non-imaging and imaging MIMO approaches: a non-imaging optical MIMO system does not perform properly at all receiver positions due to symmetry, but an imaging based system can operate under all foreseeable circumstances. Simulations show such systems can operate at several hundred Mbit/s, and up to Gbit/s in many circumstances.

Hotspots in cylindrical mirror light pipes: description and removal

The transmittance and irradiance distribution at the exit aperture of a cylindrical mirror light pipe (MLP) have been measured and calculated for the cases of collimated and diffuse inputs. MLPs are an example of a nonimaging optical system that can concentrate light, which may give rise to problematic hotspots and glare either on any diffuser used at the exit aperture or in the illuminated room. It is shown in this work that use of a diffuser at the entrance aperture overcomes these problems without a marked reduction in transmission of a typical MLP.

Development of nonimaging optics for particle counters

A nonimaging optical system is developed for particle detec- tion in an optical particle counter (OPC) with a large measurement plane, the kind of OPC required to control particle contamination in clean pro- cess gases used in chip manufacture. The measurement plane must cover the whole cross section of the gas pipe to be able to detect each particle. In a conventional OPC with imaging detection optics, local de- pendence of the particle signal is caused by the inhomogeneity of light intensity in the measurement plane as well as by local dependence of the angle of the detected scattered light. However, most important is the local signal dependence caused by the imaging detection optics. Using nonimaging elements reduces local dependence of the scattered light signal which is caused by the imaging optics. The work carried out on nonimaging light concentrators for particle detection is described. We discuss the advantages of using light concentrators, summarize the op- tical theory of light concentration and investigate the optical characteris- tics of light concentrators. Through theoretical as well as experimental tests, we show that the local deviation is less than 625.6% for a homog- enous light intensity distribution in the measurement plane. © 2000 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(00)01304-0)