Which type of filter is specified by its peak wavelength and half-height bandwidth?

The concept of peak wavelength and half-height bandwidth is critical in understanding how filters operate in optical systems. A narrow band filter is designed to transmit light within a specific range of wavelengths while effectively blocking light at wavelengths outside of this range. The peak wavelength refers to the exact wavelength at which the filter allows light to pass with maximum intensity. The half-height bandwidth signifies the range of wavelengths around the peak where the light transmission is half of the maximum value.

This characterization is essential in applications where precise wavelength selection is required, such as in spectroscopy or laser applications. A narrow band filter's capacity to restrict light to a well-defined range makes it ideal for isolating specific spectral lines. The definitions of other filters differ; for instance, broad band filters transmit a wider range of wavelengths without as much selectivity. Interference filters utilize the constructive and destructive interference of light waves to refine transmission characteristics, while long-pass filters primarily allow longer wavelengths to pass while blocking shorter ones without necessarily focusing on a narrow band.

Thus, the focus on peak wavelength and half-height bandwidth uniquely identifies a narrow band filter, making it the correct answer in this context.