Standard widefield (non-laser) filters:
“Part names beginning with ‘D ‘HQ’ ‘ET’ or ‘BP’.  These filters are intended for widefield illumination applications.  Non-laser filters with the suffix ‘x’  are categorized as “excitation” filters and are intended for use with light sources such as arc lamps, LEDs, halogen lamps, etc.  These filters provide out-of-band blocking over a very broad spectral range, as is required with a broad spectrum light source.  Non-laser excitation filters are generally not image quality.  These filters may be used in any application requiring broad out-of-band attenuation.
 
Filters with the suffix ‘m’ are categorized as emission filters and provide more narrow, targeted blocking of specified wavelengths.  Emission filters are image-quality, but will not provide the broad range of attenuation required to filter a light source.  In fluorescence applications, the emission filter is only intended to block a specific range of excitation wavelengths.  The broad blocking of a light source is provided by the excitation filter.”
 

Laser-grade filters:
“Part names beginning with ‘Z’, ‘ZET’ or ‘ZT’.  This classification refers to filters with both higher surface quality and an anti-reflection coating, and is denoted by a “z” in the prefix of the part name.  This includes laser clean-up bandpass filters (similar to excitation filters),  laser dichroics, and multi-band laser emission filters.
 
Laser clean-up filters (with prefix ‘z’ and suffix ‘x’ in part name) are coated on image quality substrates, with high quality surface flatness, parallelism and transmitted wavefront to prevent degradation of a laser beam profile.  These are intended to transmit designated laser wavelengths and prevent transmission of sidebands or Gaussian “noise”, and function as excitation filters by “cleaning-up” the transmitted laser emission.  All laser clean-up filters also have an anti-reflection coating.
 
Laser dichroics are 45 degree AOI filters, also coated on higher quality, flatter substrates, intended to minimize astigmatism resulting from surface quality in reflected laser beam applications.  These also include anti-reflection coatings.
 
Laser beam combiners, denoted by “bcm” in the part name suffix, also have improved transmitted wavefront properties, to maintain a high quality beam profile of both reflected and transmitted laser beams.
 
Multi-band laser emission filters are filters with multiple passbands and are intended to block (attenuate) the indicated laser wavelengths to an optical density of =/>OD6.
 
Laser-grade filters may also be used in widefield applications, however, laser clean-up filters might not provide blocking of ranges of wavelengths as broad as those for widefield excitation filters.”