Specifications for the SDSS filters
===================================

The SDSS filters (u'g'r'i'z') were made on the basis of 
the specifications below.

Notes.

* Basically, color glass defines the response at the 
  short-wavelength side
  and coating defines the long-wavelength side.
* (1) is specifications for glass, defining the name and 
  thickness of color glass. (2) is for coating.
* The specifications for coating are the 'standard' ones which 
  were adopted for the original SDSS filters. You can require 
  better/worse specifications depending on your purposes/budget.
* The costs per filter depend strongly on the total number of the 
  filters ordered.
  To order more than one filter of the same band at the same time
  reduces significantly the cost per filter.

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* T = transmission
* R = reflectivity
* Cutoff width is defined as 
  wavelength(T=90%) - wavelength(T=10%) 
  around T(cutoff).
* Amplitude of ripples is defined as 
  T(top of the largest ripple) - T(bottom of the largest ripple).

1. u' band

  [updated in 1998]

  (1) UG11 (1mm thickness) + BG38 (1mm thickness)
  (2) coating
      (for main part)
        T(320-330 nm)               > 80%
        T(330-420 nm)               > 90% (average)
        amp. of ripples             < 10%
      (for red leak)
        T(670 nm)                   < 1%
        T(720 nm)                   < 0.01%
        T(800 nm)                   < 1%
        T(810 nm)                   < 2%
      anti-reflection coating on the other side 
                  R<1% over the bandpass range

2. g' band

  (1) GG400 (2mm) + BG38 (3mm)
  (2) coating
        T(400-530 nm)               > 94% (average)
        T(600-750 nm)               < 0.1%
        cutoff (T=50%) wavelength   545 +- 5 nm         
        T(558 nm)                   < 10% 
        cutoff width                < 20 nm
        amp. of ripples             < 5%
      anti-reflection coating on the other side 
                  R<1% over the bandpass range

3. r' band

  (1) OG550 (4mm) + BK7 (or equivalent glass) (1mm)
  (2) coating
        T(530-675 nm)               > 94% (average)
        T(750-1080 nm)              < 0.1%
        T(1080-1100 nm)             < 0.3%
        cutoff (T=50%) wavelength   700 +- 5 nm         
        cutoff width                < 20 nm
        amp. of ripples             < 5%
      anti-reflection coating on the other side 
                  R<1% over the bandpass range

4. i' band

  (1) RG695 (4mm) + BK7 (or equivalent glass) (1mm)
  (2) coating
        T(680-832 nm)               > 94% (average)
        T(900-1100 nm)              < 0.1%
        cutoff (T=50%) wavelength   850 +- 5 nm         
        cutoff width                < 20 nm
        amp. of ripples             < 5%
      anti-reflection coating on the other side 
                  R<1% over the bandpass range

5. z' band

  (1) RG830 (4mm) + BK7 (or equivalent glass) (1mm)
  (2) coating
        R(830-1100 nm)              < 0.5%
      anti-reflection coating on the other side 
                  R<1% over the bandpass range


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The SDSS filters were manufactured by Asahi Spectra Co. Ltd. 
in Japan. 

Asahi Spectra Co. Ltd.

Optics Sales Department:
1576 Kitaakada, Nishinasuno-machi, Nasu-gun, Tochigi, 329-2741 Japan
Phone: +81-287-37-4763
Fax:   +81-287-37-4001
Contact person: Mr. T. Kimura
email:　t-kimura@asahi-spectra.co.jp
      　　　　or　
　　　　      info@asahi-spectra.co.jp

Head Office:
2-13-1 Kami-Jujo, Kita-ku, Tokyo 114-0034, Japan
phone: +81-3-3909-1151
Fax:   +81-3-3909-1152

They do not have distributor/sales centers in foreign countries.