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Optical Filter Tutorials

Wavelength budgeting for optical filters

Abstract: Considerations when specifying transition pass bands, blocking bands, and transition widths include filter manufacturing tolerances, thermal tolerances and source/detector variations among others. These factors must be taken into account properly and completely in order to achieve the spectral performance required for an application. Introduction: We are all familiar with budgeting in our daily lives […]

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How to Clean Optical Filters

How to Clean Optical Filters?While the Iridian filters are hard coated filters, the filters are delicate and should be handled with care to avoid or minimize direct contact with any other optics. All Iridian filters may be cleaned using the following recommended method. 

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How to Specify Surface Figure and Wavefront Distortion for Multi-layer Optical Filters

Optical filters are used in many applications and the surface figure and wavefront distortion requirements of filters are dependent on where and how they are used. Whereas band-pass or clean-up functionality may only require control of the transmitted wavefront, dichroic beam-steering/splitting filters or wavelength selective mirrors likely require specification of both the transmitted and reflected beams. If filters are only used in sensing applications with very tolerant detector geometries, there may be no need, in practice, to put any constraints on the surface figure or wavefront distortion. It is important to understand where, when, how, and how much to specify wavefront distortion to ensure that functional requirements are guaranteed while unnecessary and costly constraints are avoided.

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How to specify a filter

The optical filter specifications required will depend on the filter application and how it is to be used. In general, typical filter optical specifications will include the wavelength ranges over which to reflect and transmit light, angle of incidence tuning range,clear aperture of the filter, the polarization state of light for non-normal angles of incidence, […]

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