SALT Telescope ADC

The South African Astronomical Observatory (SAAO) has chosen Optical Surfaces Ltd. (Kenley, UK) to supply the two high precision prisms that make up the Atmospheric Dispersion Compensator (ADC) for the South African Large Telescope (SALT).

As part of an international consortium of leading astrophysics suppliers Optical Surfaces Ltd. will work with the SAAO to help build the single largest telescope in the southern hemisphere, with a hexagonal mirror array 11 metres across. The purpose of SALT, due for completion in December 2004, will be to record light from distant stars, galaxies and quasars a billion times too faint to be seen with the unaided eye.

Optical Surfaces components will form the core elements of the ADC whose purpose is to correct dispersion by the atmosphere of light from celestial targets entering the SALT telescope. The ADC will ride on the SALT Tracker, in the position between the Spherical Aberration Corrector (SAC) and the exit pupil of the telescope.

The SALT Atmospheric Dispersion Compensator will require Optical Surfaces Ltd. to produce two similar fused silica prisms of 290 mm diameter and a wedge angle of 7 degrees. The difficulties of qualifying and mounting these prisms are compounded by having curved surfaces, and techniques have been developed in house to solve these problems.

Comments

Post a Comment

Popular posts from this blog

What is Class I Division 2?

Image
A Class I Division 2 is a location: (1) In which volatile flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors are handled, processed, or used, but in which the liquids, vapors, or gases will normally be confined within closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown of such containers or systems or in case of abnormal operation of equipment, or (2) In which ignitable concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors are normally prevented by positive mechanical ventilation, and which might become hazardous through failure or abnormal operation of the ventilating equipment. Class I Division 2 Classification Class I Division 2 refers to the ANSI/ISA 12.12.01 standard. This standard was previously UL1604 until UL recommended the newer ANSI/ISA standard be used and that all hazardous location products be certified under this standa
Read more

FUSE SIZING CONSIDERATIONS FOR HIGHER EFFICIENCY MOTORS

Image
When selecting the proper fuse for short circuit protection in motor starting applications, it is important to not only ensure that the fuse will not nuisance open during motor start up times, but also that the fuse will coordinate as required with overload relays. When sizing fuses between 125% and 150% of the motor nameplate current, several advantages, including ease of coordination with an overload device, a smaller disconnect, and increased short circuit protection from a lower fuse rating, can be achieved. However, if sizing at this level prevents the motor from starting, it may then be necessary to increase the fuse ampere rating and it then becomes important to know the NEC sizing limitations. As of June 1, 2016, the US Department of Energy has mandated that newly manufactured electric motors will need to meet NEMA Premium® efficiency standards. As motor efficiencies increase, motor locked rotor currents can also be expected to increase. In addition to this, with across-the-lin
Read more

7/8 16UN Connectors that Provide 600 Volts and 15 Amps

TURCK announces new A-Size 3 and 4-pin 7/8 16UN powerfast™ connectors that provide up to 600 Volts and 15 Amps of power. These IP67 rated connectors provide a modular wiring system designed to handle high current applications for machine power distribution, while providing resistance to vibration commonly associated with conveyors, motors and material handling applications. The cordsets are available with a tray rated, exposed run PVC flexlife ® cable, with or without STOOW rating, and 14 AWG wires that allow you to replace hard wiring with a robust, quick disconnect system that saves the time and money spent installing a conduit system. The A-Size powerfast line offers male and female, straight connectors, standard and custom lengths, and pigtails or extensions. To make the system complete, fully encapsulated mating receptacles, with 1/2”-14 NPT mounting threads are available.
Read more