Measuring instruments and equipment: Swiss Quality


Interferometer ZGOptoTL-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 of Interferometer ZGOptoTL-60

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
- spherical surface

5 – 120 mm
5 – 60 mm
Range of surface radii at surface accuracy test:
- convex (CX)
- concave (CC)

900 mm – 3 mm
3mm – 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,
light-emitting diode
or DPSS SLM 532 nm
Weight of device ≤30 kg
Overall dimensions:

≤350 mm
≤450 mm
≤800 mm

Set of transmission spheres for interferometer ZGOptoTL-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
ZGOptoTL-60-Pl Flat infinity 60    
ZGOptoTL-60/120Pl Flat infinity 120    
ZGOptoTL-60-1:0.67CX 1:0.67 24CC 36 200CC-23CX 225CC-19CX
ZGOptoTL-60-1:0.8CX 1:0.8 39CC 49 23CX-38CX 200CC-38CX
ZGOptoTL-60-1:1.2CX 1:1.2 70CC 58 38CX-69CX 150CC-69CX
ZGOptoTL-60-1:1.8CX 1:1.8 110CC 59 69CX-105CX 110CC-105CX
ZGOptoTL-60-1:2.7CX 1:2.7 162CC 60 105CX-161CX 50CC-161CX
ZGOptoTL-60-1:4CX 1:4 240CC 60 161CX-239CX 30CX-239CX
ZGOptoTL-60-1:6CX 1:6 360CC 60 239CX-359CX 150CX-359CX
ZGOptoTL-60-1:9CX 1:9 540CC 60 359CX-540CX 330CX-540CX
ZGOptoTL-60-1:12CX 1:12 720CC 60 540CX-719CX 510CX-719CX
ZGOptoTL-60-1:15CX 1:15 901CC 60 719CX-900CX 690CX-900CX
ZGOptoTL-60-1:3.3CC 1:3.3 200CX 60 201CC-401CC 201CC-410CC
ZGOptoTL-60-1:6.6CC 1:6.6 400CX 60 401CC-601CC 401CC-610CC
ZGOptoTL-60-1:10CC 1:10 600CX 60 601CC-811CC 601CC-811CC
ZGOptoTL-60-1:13.5CC 1:13.5 810CX 60 811CC-1020CC 811CC-1020CC

Important notice about testing of spherical surfaces and the diameter of collimator

Important to underline, that principle thing in the process of testing 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 ZGOptoTL-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 ZGOptoTL-60 a reference lens ZGOptoTL60-1: 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 ZGOptoTL60-1: 2.7CX are used, respectively, wherein the diameter for ZYGO is 116:3.3=35 mm, and for ZGOptoTL-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 ZGOptoTL – 47 mm.

Thus, for the selected radiuses the diameter of surfaces when checking by interferometer ZGOptoTL-60 is approximately by 20% bigger compared with the diameter when checking by interferometer ZYGO4".
Therefore ZGOptoTL60’s smaller collimator covers in many cases bigger surface diameters which, together with smaller price, can be attributed to its advantages.

Fin-de-Praz 24, CH-2024 St-Aubin, Switzerland tel +41 (0)32 835 35 15 fax +41 (0)32 835 35 54