Beam Relay Research Articles

CNN to mitigate atmospheric turbulence effect on Shack-Hartmann Wavefront Sensing: A case study on the Magdalena Ridge Observatory Interferometer.

The Magdalena Ridge Observatory Interferometer (MROI) utilizes Shack-Hartmann Wavefront Sensing (SH-WFS) for the back-end stability of its beam relay systems in a unique design. The SH-WFS, however, is sensitive to atmospheric turbulence scintillation which can drastically affect its precision in calculating the position of the beam profile it sees. A large number of images are needed to counteract the turbulence effect. Here we use deep learning as an alternative to long averaging cycles. A CNN was trained to map from a number of initial images of a series of star frames to the average image of the entire series at different positions of the beam profile. Under typical seeing conditions expected at MROI, the results showed that the network can map 10 input frames to the average of 100 within the permissible error margin of 0.1 pixels and furnish proper generalization to beam position movements not seen during training. The network can also outperform the averaging technique when both techniques operate on small numbers of input frames such as 10 or 20.

PENGGUNAAN BALOK CUISENIARE UNTUK MEDIA PENGENALAN BILANGAN BAGI ANAK USIA DINI

Learning activities carried out in RA Al-Istiqomah still have children who have difficulty to say or list the numbers 1 to 10, children have difficulty in pointing with objects, children have difficulty making sequences of numbers 1 to 10 using objects, children have difficulty showing symbols numbers 1 to 10, children have difficulty in recognizing many objects slightly the same and not the same thing. Children have difficulty showing 2 sets of objects that are equal in number, which are not the same, more and less. Teaching numerals to children requires interesting media for children, the success of early childhood learning is influenced by the media used, one of the stimulations that need to be done to stimulate children's ability to say is to introduce numbers to early childhood. To introduce numbers in early childhood to feel happy and interested, it is necessary to apply the right media, one of which is playing the Cuisenaire beam. The purpose of this study was to describe about 1) Knowing the learning of Cuisenaire beam game tools in spelling on RA Al-Istiqomah group A. 2) Knowing the ability to say at RA Al-Istiqomah group A after being given the actions of the Cuisenaire beam game tool. The method used in this study is classroom action research conducted through two cycles. From the results of evaluations, reflections, and improvements made at the end of the cycle, a description of the use of the Cuisenaire beam props that can improve the ability to say group A follows the steps as follows: a) The teacher prepares the Cuisenauire beam. b) The teacher invites children to play cuiseniare beams with the learning activities that have been determined. c) The teacher guides the child to make two groups, each group consisting of 3 to 4 children. d) The teacher starts the Cuisenaire beam relay game.

Design and fabrication of microlens arrays as beam relay for free-space optical interconnection

In this paper we report the design and fabrication of a beam relay for free space optical interconnection using microlens arrays. Multiple microlens arrays with same focal lengths were designed and fabricated in an out-of-plane layout. This design can be easily integrated with silicon-based optical interconnection devices. The beam relay was fabricated using direct lithography of SU-8 photoresist, and then replicated using UV curable polymer molded with a PDMS intermediate mold. The optical performance was tested and the experimental results show that the optical performances are mainly limited by the aberration of microlenses. Further study needs to be conducted to improve the surface quality of the lenses to reduce the aberrations.

Analysis of laser beam relay optics design

The problems of using one focusing lens (group) to relay a laser beam are analyzed. A two-focusing lens (group) is proposed, which can relay most laser beams.

The ALFA Laser: Beam Relay and Control System

The ALFA laser subsystem uses a 4 watt continuous wave laser beam to produce an artificial guide star in the mesospheric sodium layer as a reference for wavefront sensing. In this article we describe the system design, focusing on the layout of the beam relay system. It consists of seven mirrors, four of which are motor-controlled in closed loop operation accounting for turbulences inside the dome and flexure of the main telescope.The control system features several computers which are located close to analysis and control units. The distribution of the tasks and their interaction is presented, as well as the graphical user interface used to operate the complete system. This is followed by a discussion of the aircraft detection system ALIENS. This system shuts off the laser beam when an object passes close to the outgoing laser.

High damage threshold [formula omitted] dielectric coatings for excimer lasers

Today there are hardly any products in optical industry which do not employ optical coatings. Mainly in the UV spectral region, laser induced damage thresholds of these coatings are a limiting factor for the development of cost-effective optics. The high power optical components and dielectric coatings have to be developed to cavity optics, beam relay optics, mask imaging optics, and masks. Therefore, we used ultralow loss conventional electron-beam evaporation for Al2O3SiO2 dielectric multilayers. Based on a fundamental coating technique, both multilayer mean background absorption and absorption at localized spikes have been reduced drastically. The resulting KrF laser damage threshold of HR coatings is 16 J cm−2 (1-on-1, 30 ns MSC). Multilayers have been characterized by atomic force microscopy, photothermal microscopy, absorption measurements, and spectroscopy of sputtered neutrals.

UV losses in MgF 2 thin films induced by the evaporation boat

Today there are hardly any products in optical industry which do not employ optical coatings. Mainly in the UV spectral region, laser induced damage thresholds of these coatings are a limiting factor for the development of cost-effective optics. The high power optical components and dielectric coatings have to be developed to cavity optics, beam relay optics, mask imaging optics, and masks. Therefore, we used ultralow loss conventional electron-beam evaporation for Al2O3SiO2 dielectric multilayers. Based on a fundamental coating technique, both multilayer mean background absorption and absorption at localized spikes have been reduced drastically. The resulting KrF laser damage threshold of HR coatings is 16 J cm−2 (1-on-1, 30 ns MSC). Multilayers have been characterized by atomic force microscopy, photothermal microscopy, absorption measurements, and spectroscopy of sputtered neutrals.

Holography Applied To Inspection And Measurement In An Industrial Environment

The three-dimensional imaging capability, enormous information storage capacity, and the related very high resolution of images when they are correctly reconstructed combine to make holography an inspection tool of immense power and utility in capital-intensive industries. This paper describes work in the U.K. electricity-generating industry aimed at enabling high grade holograms to be routinely recorded in a wide range of industrial situations where high speed acquisition of visual data is desirable. Specific applications to be described are holography of nuclear reactor cores and of irradiated fuel elements for inspection after withdrawal from the reactor. Accurate recon-struction of images and precise, three-dimensional measurement of recon-structed images in a laboratory environment are then undertaken with computer-controlled micronlanipulator equipment traversing a television camera within the real image. Measurements of a 1 m long fuel element to within 0.1 mm have been demonstrated and resolutions of 50 line pairs/mm have been obtained on the reconstructed object. The paper describes work on in-reactor inspection in which the pulsed ruby laser used to record the holograms is routinely aligned to a 15 m beam relay and remote holographic head. Three-dimensional reconstruction and hologrammetry are described, and plans for automated measurement and inspection using image enhancement techniques are discussed.