A microscope whose objective is composed of two mirrors, one convex and the other concave. The imaging properties are independent of the wavelength of light, and this freedom from chromatic aberration allows the objective to be used even for infrared and ultraviolet radiation. Although the reflecting microscope is simple in appearance, the construction tolerances are so small and so difficult to achieve that the system is used only when refracting objectives are unsuitable. The distance from the objective to the specimen can be made very large; this large working distance is useful in special applications, such as examining objects situated within metallurgical furnaces. Reflecting microscopes have been mainly used for microspectrometry in the infrared and the ultraviolet, and for ultraviolet microphotography.