Aspherical MirrorsOff-axis Parabolic Mirrors

Off-axis Parabolic Mirrors


An off-axis parabolic mirror converts plane waves into spherical ones and vice versa with high accuracy. This aspherical mirror is indispensable for spectrometers and astronomical optical instruments which require high resolution.

When a spherical mirror is used under off-axis conditions, spherical and coma aberrations occur, which cause the degradation of resolution of a spectrometer. Off-axis parabolic mirrors theoretically eliminates these aberrations and ensures high resolution even in a short focal length compact spectrometer.

The off-axis parabolic surface used in Shimadzu off-axis parabolic mirrors is, when expressed mathematically, a part of a rotary symmetric parabolic surface represented by Y = X2/4F (where, F: focal length, Y is the rotary symmetric axis and X is the displacement on the axis.)


  • Shimadzu off-axis parabolic mirrors are replicated by master mirrors that pass through rigorous inspections such as zone, Foucault, and interference tests.
  • At the rear side of each mirror, a notch is grooved to indicate the mounting direction (points to the rotary symmetric axis).

Product List(Table of Code Number)

Code Number*1 On-axis focal length f(mm) Off-axis focal length f'(mm) Off-axis angle
Dimensions W×H(mm) Effective area FA(mm) Central thickness T(mm)
125-15-4040 125 134 15 40×40 Φ36 16
200-09-4040 200 205 9 40×40 Φ36 16
200-12-4040 200 209 12 40×40 Φ36 16
275-07-4040 275 279.1 7 40×40 Φ36 16
275-09-4040 275 281.9 9 40×40 Φ36 16
275-09-6575 275 281.9 9 65×75 Φ60 16
275-06-5555 275 277.5 5.5 55×55 Φ50 16
275-07-6060 275 279.1 7 60×60 Φ55 16
787-03-6464 787 789.2 3 64×64 Φ60 16
  • *1: Code Number Meaning :
Code Number Meaning


Classification Replica parabolic mirror*2
Blank Material Soda glass
Dimensional Tolerance(W,H) 0/-0.2 mm
Central Thickness Tolerance(T) ±0.2 mm
On-axis Focal Length Tolerance(f) ±0.5%
Surface Accuracy Within λ /2*3
Effective area(FA) Ref table
Coating Aluminum
Scratches & Digs 80-50(as per MIL-O-13830A)
  • *2:Paraboloidal surface is formed by resin.
  • *3:λ =632.8nm
  • ※RoHS compliant (Directive 2011/65/EU + (EU)2015/863 on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment)
  • ※Thermal and Humidity Conditions for Storage:0℃ to 50℃, 50% RH max.(no conensation) *When temperature is from 0℃ to 40℃, humidity should be 80% RH max.

Schematic Diagram

Schematic Outline


  • Spectrometers
  • Interferometers
  • Astronomical optical instruments
  • Spectrum analyzers
  • Beam Expander and Beam Collimator

Examples of application in spectrometers

Littrow-type spectrometer
Littrow-type spectrometer
Czerny-Turner spectrometer
Czerny-Turner spectrometer

Optional Specification

  • Off-axis parabolic mirrors with the following optional coating are available upon request
  1. Al + MgF2 (for vacuum ultraviolet)
  2. Au (for vacuum ultraviolet)
  3. Au (for infrared)

For more information, please contact us.

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