This week MOONS has taken delivery of its first major optical components, the RI band dichroics. Each of the two MOONS spectrographs has three different spectral channels; light is split into these channels through two dichroics. The dichroics received are the first ones in the beam, which reflect the short wavelength radiation into the RI camera and allow longer wavelength light to pass through.

These optics have been manufactured for the MOONS consortium by the US company Materion. At around 40 x 30 cm, they are extremely large optics to manufacture and handle. We are delighted to report that the as-built transmission and reflection properties of these optics exceed the requirements we had requested from Materion, which is obviously excellent news.

The second set of dichroics, that reflect light into the YJ cameras, have also been manufactured and should be delivered to the consortium very shortly.

One of the two large dichroics safely encased in its transport case, which we are not opening until ready to install the optics in its mount next year. It is hard to appreciate the scale here, but the holes on the table surface are 2.5 cm apart. 
Photo 09-11-2018, 13 26 08
A dichroic in action! This ‘selfie’ of some of the MOONS team clearly shows light reflected off the front and the back surfaces of the dichroic (the blue and the red reflections) and also the colour (less clear) reflection off the plastic case in which the dichroic sits.

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