Multi-notch holographic filters for atmospheric lines suppression
Near-infrared emission from atmospheric OH radicals is known to severely affect astronomical observations. Until now, only complex dispersive instruments were partially capable of removing this unwanted background, which is composed of hundreds of narrow emission lines. Recent development in photosensitive glass and holographic recording technologies now allow the elaboration of filters with a large number of narrow reflecting bands well matched to OH lines. This technology shows promise for removing many tens of lines in the J, H, and K bands. That would result in a many fold increase in imaging and low resolution signal-to-noise ratio. Filters with 10 lines have been tested and show the appealing possibilities of these new devices.