Optical filter wavefront distortion: out-of-band to in-band predictions and the effect of the illumination source bandwidth. Read or download the full article in PDF format.
In designing a filter solution, the filter manufacturer takes the values requested by the user and adds additional design margin to account for both...
Abstract: Considerations when specifying transition pass bands, blocking bands, and transition widths include filter manufacturing tolerances,...
The wavefront error (WE) of a surface with an optical coating (“filter”) is ideally measured at the in-band wavelength of the filter. However, quite often this is not possible, requiring that the filter be measured at an out-of-band wavelength (typically 633 nm), assuming that the filter transmits (for transmitted WE, or TWE) or reflects (for reflected WE, or RWE) at this wavelength. This out-of-band TWE/RWE is generally assumed to provide a good estimation of the desired in-band TWE/RWE. It will be shown in this paper that this is not the case for a large class of filters (i.e., bandpass) where the group delay is significantly different at the in-band and out-of-band wavelengths and where the optical filter exhibits a thickness non-uniformity across the surface.
1 Introduction Large format (>100 mm diameter), narrow bandpass filters (NBPF) are required in many fields. Applications requiring a large...
Gain Flattening Filter (GFFs), also known as gain equalizing filters, are used to flatten or smooth out unequal signal intensities over…
Tap couplers filters and beamsplitters are used to reflect a specific percentage of incident light over a broad wavelength range and for a specified angle of incidence. Beamsplitters and tap couplers can be specified…
Coarse Wavelength Division Multiplexing (CWDM) filters are designed to multiplex and de-multiplex wavelength signals in metropolitan, access and enterprise networks and for Cable TV applications. In addition…
Linear Transmittance Filter (LTF) has a transmittance that is changing linearly over a specified wavelength range. LTFs are typically used for…
The Single Cavity Filter (SCF) is used to select a single frequency from a broad spectral range. SCFs are typically used for…
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