Dear Agung Shamsuddin,

you need a filter which will block everything below 350nm whilst allowing
reletively good transmission above this. In the past I have used a piece of 2mm
thick HOYA UV-34 filter glass with a MJB 3 after it was recommended to me by
posters on this board. This worked very well.

Please feel free to email me directly with any other questions on this.

Regards,

Novak
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Novak Farrington
School of Electrical and Electronic Engineering
University of Manchester