Optimised CCD Anti-Reflection Coating

Graded thickness AR coating (for fixed-format spectroscopy)

Andrew Kelt, Andrew Harris and Paul JordenE2V Technologies, 106, Waterhouse Lane, Chelmsford, Essex, CM1 2QU, United Kingdom

Simon TullochIsaac Newton Group, Apartado De Correos 321, 38700 Santa Cruz de La Palma, Islas Canarias, SPAIN

•Backthinned CCDs normally use a single wavelength antireflection coating to maximise QE

•E2v designed custom evaporation technique to allow a graded AR coating

•Test results –Optimised spectral response from 300-1000 nm along 60mm length of

the sensor.

Reduction of fringes when minimum reflection matches illuminated wavelength.

•Results of spectral response, reflectivity, and fringe amplitudes are presented.

This side of CCD is optimised for the blue

This side of CCD is optimised for the red

Sample CCD44-82 with graded coating

Optimised CCD Anti-Reflection Coating

Optimised CCD Anti-Reflection Coating

Deep Depletion astro QE -100C modelse2v technologies

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QE

NIR110nm

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QE: DD. Si, astro process, -100C

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wavelength (nm)

QE

dd Si astro broadbandcomparison

optimised (graded) QE

SUMMARY

•Low reflectivity = High QE Optimises QE across full wavelength range.

• Low reflectivity in the red = Low fringing Reduced fringes at red wavelengths

• AR coat can be matched to spectrograph output. Ideal choice for Fixed Format Spectrographs.

Optimised spectral response cf fixed

wavelength AR coat

[Curves are for deep depletion CCD]

Please see poster for all the other data. Thanks!

Optimised CCD Anti-Reflection Coating