We describe the method for optical design of afocal achromatic systems that keep their characteristics stable in a wide thermal range without refocusing. Usually, thermal stabilization of the back focal length of an optical system is considered, but these methods are not directly applicable for afocal systems. The method proposed is based on the idea of using a proper combination of optical materials and powers of optical elements to keep the whole system as an afocal one in the desired temperature range. As an additional advantage, the method has shown that afocal systems have enough parameters to achieve achromatic correction and may take into account the F-number of optical elements, which is important for the aberration balance. The research presents both theoretical statements and the example of a laser beam expander for dual wavelengths. The method can also be used to design afocal achromatic compensators that help to achieve thermal stability.
Today many HMD systems are implemented in monocular design but for more comfort and informative work system should be binocular (or binocular), however not all optical schemes allow this to be done.
The work presents the analysis of modern solutions of Head-mounted optical systems design and an assessment of the feasibility of using certain systems in the form of binocular or biocular helmet displays.
The goal of such contest concludes in the massive involvement of undergraduate and graduate students into solution of tasks from various areas of modern photonics – from material science till light design and AR/VR systems.
Despite main part of the contest is provided by the ITMO University and its regional partners, a set of leading industry companies supported the contest. Their motivation is in direct communication with talented students – future professionals.
This challenging project poses many tasks and makes the organization committee and the team who prepares the event to solve many tasks: organize network collaboration between many universities and industry companies to prepare the content for the event, notify the potential participants, motivate them (both sides), hold the contest in the same time with many participants over the big country and check the tasks in various fields by the experts.
We present our experience in organization of such an event and discuss some features, results and perspectives.
In the project, we consider systems for the edge lighting of relatively small displays approximately 20 x 30 mm. Only one LED with nearly lambertian spatial distribution was used in the system. The optical system consisted of a wedge lightguide and a reflective surface, the surface can be either smooth or structured (with array of certain structure).
Various combinations of the wedge lightguides with the structured reflective surfaces were considered in the study, the designed variants were also compared to the systems with BEFs.
The designed systems provide acceptable illuminance uniformity for the central display zone, with small dark zones on the display margins. As a result of its simple construction and the ease with which it can be manufactured, the developed system, which has only one LED source, has potential applications in situations where the requirements for illuminance uniformity are not very high, for instance, in indicator devices.
The key feature of an optical system in this case is having the highest functionality, to meet this demands it should be able to work on variable distances and provide the minimal light spot. The purpose of the work is a research of the best possible initial system parameters and its components, designing of an optical system with minimum possible number of elements providing acceptable quality of the image in the required dimensions. An image quality criterion for such systems is the size of the light spot, which defines an operation speed of the system.
Using the beam diameter and allowable system dimensions as initial parameters of the two components system, relations were found which helps to define optimal component parameters for future design. To provide the possibility of working on various distances the thickness between the components can be varied.
An example of a two component system consisted of three lenses with spherical surfaces is presented. The system works with a laser with the wavelength of 0.785 μm and provides the light spot less than 2.3 mm for all working distances within the range of 2 – 5 m.
One of the main requirements of the Education Ministry to such events is that the competition must include both practical and theoretical parts. Practical part usually includes several tasks, and each task is a demonstration of an optical phenomenon or an optical instrument or device and involves questions concerning the demonstrated experiment. Theoretical part is a set of tasks and questions that should be solved and answered in written form. Organization committee and judges which are the members of teaching staff of different universities prepare complex theoretical tasks and arrange a set of practical questions. Nevertheless the set of task may include simple questions which can be solved using basic knowledge of optics, observation and erudition. Thus, such competitions help to discover the most talented and motivated students which have great potential.
In the report the problems of organization and carrying out of such competition in optics are discussed. Examples of tasks which were used in different years and also retrospective of the competition are presented.
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