Product

Optical Devices

Off-axis Parabolic Mirrors

Off-axis Parabolic Mirrors

Off-axis Parabolic Mirrors

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

Generally, when a spherical mirror is used under off-axis conditions, there appear spherical aberration and coma, which are principal causes in the degradation of resolution of a spectrometer. An off-axis parabolic mirror theoretically eliminates these aberrations and ensures
high resolution when used even in a short focal length compact spectrometer.

The off-axis parabolic surface used in the 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.)

Features

  • he off-axis parabolic mirrors feature reliable quality, being replicates manufactured by using the master mirrors which have passed precision inspections such as zone tests, Foucault tests, and interference methods.

  • At the rear side of each mirror, a C mark is provided to indicate the mounting direction (points to the rotary symmetric axis).

Standard Specifications

Tolerance in external dimension (W and H) 0/-0.2mm
Tolerance in central thickness (T) ±0.2mm
Tolerance in focal length (on axis) ±0.5%
Tolerance in axis displacement ±2mm
Surface accuracy 0.3µm
Blank material Soda glass
Coating Aluminum
Effective area Ref table
Scratches & digs(in accordance with MIL-0-13830A) 80-50
Storage temperature 0°C -50°C
Storage humidity (with no condensation) 80% RH or less

Standard Products

Width
W (mm)		 Height
H (mm)		 Central
thickness
D (mm)		 Focal
length
(on axis)
f (mm)		 Focal
length
(off axis)
f ' (mm)		 0ff-axis
angle
(q )		 Axis
displacement
A (mm)		 Vertical depth
V (mm)		 Effective
area (mm)		 Part No.
(P/N)
40 40 16 125.0 134.0 15 67.0 9.0 j 36 205-84354
40 40 16 200.0 205.0 9 63.3 5.0 j 36 205-84356
40 40 16 200.0 209.0 12 85.0 9.0 j 36 205-84357
40 40 16 275.0 279.1 7 67.5 4.1 j 36 205-84358
40 40 16 275.0 281.9 9 87.1 6.9 j 36 205-84329
55 55 16 275.0 277.55 5.5 52.96 2.55 j 50 205-84370
60 60 16 275.0 279.1 7 67.5 4.1 j 55 205-84378
64 64 16 787.0 789.16 3 82.49 2.16 j 60 205-84381

Schematic Outline

Schematic Outline
Applications

  • 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
Type:
  1. Al + MgF2 (for vacuum ultraviolet)
  2. Au (for vacuum ultraviolet)
  3. Au (for infrared)

page top