WIYN Observatory


ODI News Roundup: June 2010

Prism Bonding

A major milestone was reached this week when the first pair of glass wedges were cemented together to form one of the two prisms for ODI's atmospheric dispersion compensator. ODI is designed to deliver the best possible image quality, but one source of image degradation is the earth's atmosphere.

Earth's atmosphere itself acts like a prism; that is, it spreads out the light into a spectrum. This effect is too tiny to be noticeable with the naked eye, but with ODI's excellent image resolution, this so called "atmospheric dispersion" would have a significant impact and would be visible as an elongation of stars.

To correct this dispersion, a pair of prisms is included in ODI's optics. These prisms are carefully designed to factor out the atmosphere's dispersion. This set of optics is called the atmospheric dispersion compensator (ADC). As part of ODI's ADC design, two different kinds of glass wedges need to be fused together with a special optical cement. After long and painstaking preparation and training, this delicate procedure was successfully completed this week in the cleanroom facilities at NOAO for the first set (see pictures below). Congratulations to the ODI team.

Now the cement between the two wedges must cure at a controlled temperature of 11°C before the prism will be mounted into its fixture. The curing temperature has been set to match the expected mean temperature at which the ADC will operate on the WIYN telescope at Kitt Peak. Next week, a second pair of wedges will undergo the same process, and all optic components of ODI will be complete.

Cementing of the first two ADC wedges

Cementing of the first two ADC wedges

The first ADC wedges successfully bonded together

The first ADC wedges successfully bonded together


The ODI team will present a total of four papers at the June SPIE meeting in San Diego. The papers are available at http://spie.org/x13662.xml, and also on the ODI web page.

Last modified: 23-Sep-2015 14:59:03 MST