Interferometers to test accuracy of optical surfaces, to measure radii and to check TWD of objectives.


Main advantages of interferometers OptoTL:

  • Small size for easy placing close to machines in busy optical shops with intensive foot traffic.
  • Specially designed original FastInterf software for simple and fast measuring procedure in production conditions.
  • Two nearby located monitors for quick adjusting and visualizing the interferometric picture.
  • Large set of transmission spheres (table below).
  • Set of adjusting stages for components under test.
  • The modular design concept to reconfigure the Interferometer quickly for various needs.
  • Centering test of single lenses as well as lenses in housing.
  • Double speed vertical motion driver for quick and precise adjusting.
  • Passive anti-vibration system.
  • Rigid design reducing vibration effect up to the level necessary for computer measurements.

FastInterf software

Calculation time – several sec.

Calculation of all standard errors corresponding to optical surface and through-passing wavefront:

  • (P-V) error;
  • (RMS) error;
  • defocus (power);
  • 3rd order aberrations;
  • Zernike polynomial coefficients;
  • results of calculations are presented in various forms, including 3D surface topography;
  • presentation of computer generated interferometric pattern for visual evaluation of the results authenticity.
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Modernization of the software – in accordance with customers’ requirements.

Interferometer OptoTL-60

Interferometer OptoTL-60 is applied for contactless technological testing of the accuracy (Power/Irregularity) of polished flat and spherical surfaces, for measuring of surfaces’ radii and for checking of transmission wavefront distortion (TWD) of objectives.

Technical parameters
Optical scheme
Fizeau
Arrangement of optical axis of the system Vertical
Type of surface under test Optical, polished
Shape of surface under test Plane, spherical
Refraction coefficient of surface under test
1-99%
Diameter range:
  • plane surface
  • spherical surface
  • 5 mm – 120 mm
  • 5 mm – 60 mm
Range of surface radii at surface accuracy test:
  • convex (CX)
  • concave (CC)
  • 900 mm – 3 mm
  • 3 mm – 1100 mm
Range of testing radii: 
  • convex (CX)
  • concave (CC)
  • 200 mm – 3 mm
  • 3 mm – 200 mm
Accuracy of radii test (depends on environment)     2-10 µm
Testing accuracy P-V λ/10
Maximum value of the  error to measure
Light source
HeNe 633 nm or DPSS SLM 532 nm
Weight of device
<=30 kg
Overall dimensions:
  • length
  • width 
  • height

  • <=350 mm
  • <=450 mm
  • <=800 mm

Set of transmission spheres for interferometer OptoTL-60

Reference surfaces are tested with Zygo interferometer. Transmission spheres are calibrated with CaliBall ™ (interferometer calibration device) by using the Random Ball Test.

Addition transmission spheres according to customers’ requirements can be manufactured.

Type of mouthpiece with transmission sphere Output
F#
Standard surface radius,
mm
Standard surface diameter,
mm
Region of tested radii (optimal for max F#),
mm
Region of tested radii (feasible),
mm
Optotl-60-Pl Flat
infinity
60
Optotl-60/120Pl Flat
infinity
120
Optotl-60-1:0.67CX 1:0.67 24CC 36 200CC-23CX
225CC-19CX
Optotl-60-1:0.8CX 1:0.8 39CC 49 23CX-38CX
200CC-38CX
Optotl-60-1:1.2CX 1:1.2 70CC 58 38CX-69CX
150CC-69CX
Optotl-60-1:1.8CX 1:1.8 110CC 59 69CX-105CX
110CC-105CX
Optotl-60-1:2.7CX 1:2.7 162CC 60 105CX-161CX
50CC-161CX
Optotl-60-1:4CX 1:4 240CC 60 161CX-239CX
30CX-239CX
Optotl-60-1:6CX 1:6 360CC 60 239CX-359CX
150CX-359CX
Optotl-60-1:9CX 1:9 540CC 60 359CX-540CX
330CX-540CX
Optotl-60-1:12CX 1:12 720CC 60 540CX-719CX
510CX-719CX
Optotl-60-1:15CX 1:15 901CC 60 719CX-900CX
690CX-900CX
Optotl-60-1:3.3CC 1:3.3 200CX 60 201CC-401CC 201CC-410CC
Optotl-60-1:6.6CC 1:6.6 400CX 60 401CC-601CC 401CC-610CC
Optotl-60-1:10CC 1:10 600CX 60 601CC-811CC 601CC-811CC
Optotl-60-1:13.5CC 1:13.5 810CX 60 811CC-1020CC 811CC-1020CC

Please note that main importance in the process of the test of spherical surfaces is not the diameter of collimator but the relative aperture (f-number).

Let us explain this comparing the testing of convex radiuses 46 mm, 116 mm and 285 mm by the interferometer ZYGO 4" with collimator’s diameter of 100 mm and by interferometer OptoTL-60 with collimator’s diameter 60 mm.

In order to check the radius 46 mm by interferometer ZYGO 4" a reference lens ZYGO f / # 1: 1.5 is used, and the diameter of the test surface is 46:1.5 = 31 mm. To check the same radius by the interferometer OptoTL-60 a reference lens OptoTL60-1: 1.2CX is used, and the diameter of the test surface is  46:1.2 = 38 mm.

For a radius 116 mm a reference lens ZYGO f / # 1: 3.3 and OptoTL60-1: 2.7CX are used, respectively, wherein the diameter for ZYGO is 116:3.3=35 mm, and for OptoTL-60 is 116:2.7=43 mm.

By the same logic for the radius of 285 mm the diameter at ZYGO is 40 mm and at OptoTL – 47 mm.

Thus, for the selected radiuses the diameter of surfaces when checking by interferometer OptoTL-60 is approximately by 20% bigger compared with the diameter when checking by interferometer ZYGO4". Therefore the bigger collimator in interferometer is not always the advantage, but it always leads to increase in cost.

Interferometer OptoTL-250

Interferometer OptoTL-250  is applied for contactless technological test of the accuracy (Power/Irregularity) of polished flat surfaces with Dia up to 250 mm.

Technical parameters

Optical scheme
Fizeau
Arrangement of optical axis of the system
Vertical
Type of surface under test
Optical, polished
Shape of surface under test
Plane
Refraction coefficient of surface under  test  1-99%
Diameter range:
  • plane surface
25 mm – 250 mm
Testing accuracy P-V
λ/10
Maximum value of the  error to measure
Light source
HeNe 633 nm or DPSS SLM 532 nm
Weight of device
<=250 kg
Overall dimensions:
  • length
  • width
  • height

  • <=500 mm
  • <=500 mm
  • <=950 mm

To meet specific customer’s needs further upgrade and modernization of the above models are possible.