Development of metal mesh filter technology to enable next generation FIR astronomical instruments

Next generation far infrared instrument proposals for space missions present some interesting and challenging optical filtering requirements. There is a combined need for: shorter wavelength (down to 20µm) FIR filters and dichroics tailored for observational band selection; tight control of bandwidths and rejection of out-of-band radiation; and instrument thermal control. <br/> <br/> Here we review the current state of the art for these devices for applications shorter that 200 µm (low-pass, high-pass and band-pass filters, polarisers, dichroics and beam-dividers); we discuss current developments and technological limitations and present solutions for future FIR instrument concepts.