Ultra-narrow-band tunable filters allow imaging of the Sun in bandpasses sufficiently narrow to isolate individual spectral lines and to determine their profiles. Now in orbit are filters with bandpasses of resolution 50,000-100,000 and in development is a filter of resolution 100,000 that will tune with milliangstrom precision over the spectral range from 5000A to 6800A.

Normal incidence mirror technology in the extreme UV allows resolutions of 10 to 100 from about 100A to 300A. Examples will be shown of the devices that accomplish this and results obtained to date with them.