UBVRI Filters for Astronomy
Johnson/Bessell Type
Kron/Cousins Type

Andover Corporation is now offering UBVRI filters as standard items. These filters are used to filter out and measure specific bands of light which are emitted by astronomical objects.

Two types are offered: the Johnson/Bessel and the Kron/Cousins. The Johnson/Bessell type is better suited for use with a photomultiplier tube whereas the Kron/Cousins type is better suited for use with a Silicon CCD. Both filter sets work very well but it is important to establish the type of measuring system you are going to utilize before purchasing any sets.

Both filter types utilize the same U, B & V filters. The R & I filters for each type are different; they are better matched to the response of the detector being used.

Refocusing, is always a problem when changing filters, Andover has minimized this problem by grinding and polishing all filters to a very precisely controlled thickness.

The UBVRI filters are available in a range of standard and custom sizes. With the exception of two sizes which are mounted in threaded rings, all other sizes are unmounted. Contact Andover Technical Sales if you have any questions or require a quotation for a custom size or mounting.

 
 Mechanical Specifications
  
Size Tolerance:
   +0/-0.25mm
Glass Thickness:
 5.0mm +/-0.1mm
Bevels:
 Break all sharp edges
Mounting:
 See below
Coating durability:
 Per MIL-C-48497A
moderate abrasion
Construction: Schott glass substrates
(ground and polished)
laminated with
index-matching epoxy.
 
Optical Specifications
  
Transmitted Wavefront:
   1/4 wave or better
per 25mm
Parallelism:
 30 arc seconds or better
Surface Quality:
 60/40 or better per
MIL-C-675
A/R coatings:
 Exterior surfaces
(appropriate to the
filter passband)
 
Quality Data
  
Transmitted Wavefront (TWF) data
supplied with each filter
 
Each filter will be supplied with a spectrophotometric data curve encompassing the passband of the filter
 
Available sizes
  
Unmounted:
   25mm dia.
28mm dia.
32mm dia.
38mm dia.
50mm dia.
50mm sq.
Mounted: 31mm dia. threaded ring
50mm dia. threaded ring
 
Detailed Specs and Graphs
  
Custom UBVRI filters, manufactured to your specifications, are also available. Contact our technical sales department for a quotation.