Broader scope of optical astronomy
Infrared, ultraviolet and optical astronomy.
While popular use of the term still means its historical meaning (that is, limiting it to the visible astronomy) that kind of astronomy is now more accurately called by scientists as visible light astronomy.
The term optical astronomy is now being used to refer to other types of astronomy at other electromagnetic spectrum: infra-red and ultra-violet astronomy in addition to visible light astronomy.
Optical astronomy
Optical astronomy, in a strict scientific way, not only refers to visible light astronomy, but also refers to astronomy at infrared and ultra-violet spectrum. Observations at these wavelengths involve optical devices (lenses, mirrors and digital detectors).
Infrared astronomy
Infrared astronomy deals with the detection and analysis of infrared radiation - electromagnetic radiation that falls in the wavelength range 750 nm and 1mm.
Ultraviolet astronomy
Ultraviolet astronomy refers to astronomic observation at ultra-violet wavelengths between 10nm - 320nm.