Optical components and systems maker Gooch & Housego reported an 11.3% drop in half year EBITDA as challenging conditions continue.Adjusted EBITDA fell to £2.6m for the 6 months ended 31 March 2009 from £3.0m in 2008. Group revenue for the period was up 20.1% to £18.8m. Revenue, excluding acquisition and FX benefit, was down 18.2%.The interim dividend has been omitted.The results came after "challenging market conditions in the industrial laser market," the group said in a company statement."The first half of our current financial year has continued to be challenging. On a like for like basis we have seen a decline in our revenues and profits when compared with the first half of last year despite the benefits of the strong dollar," the group added.