Triple-Beam Plane-Mirror Interferometer
SP-TR Series
Design and Operation
The triple-beam interferometers are precision length measuring instruments, that combine three interferometers in one instrument. This enables three lengths to be measured simultaneously with nanometer accuracy. The corresponding angle can be calculated with great accuracy from the difference between two length values and the beam distance. A HeNe laser with a highly stable frequency supplies all three interferometers. The three measuring systems all have the same wavelength standard. The laser beam is coupled with only one fiber-optic cable in the sensor head. The triple-beam interferometer converts the measuring movements into interference signals, which are transmitted to the electrical supply and evaluation unit. The high measurement accuracy is achieved by using an HeNe laser as the dimensional standard and by correcting environmental effects on the laser wavelength. Operation and display take place on a PC with optional data acquisition and display software.
Major Performance Features
• Simultaneous, ultraprecise, triple-channel length measurements, as well as pitch and yaw angle measurements
• The same laser wavelength is used in all three measuring channels
• The beam distances are calibrated in the factory
• Fiber-optic coupling of the sensor head • The sensor head may be made of aluminum, stainless steel or invar
• Open interfaces for OEM software under Windows and Linux
Operating Principle
Applications
• Laser-interferometric measurements on guides, measuring, microscope and positioning tables
• High precision pitch and yaw angle corrections at two or multicoordinate measurements
• Calibration of measuring machines and machine tools
• Difference measurements (dilatometry, material testing)
• Extension of the measuring range for angle measurement on request
Technical Data
Model SP 120 TR Model SP 2000 TR Length measuring range (max. distance from reflector to sensor head)
mm
70
2000
Length resolution
pm
20
20
Laser wavelength
nm
632.8
632.8
Frequency stability of the HeNe laser (after warm-up time)
3 ∙ 10-7
2 ∙ 10-8
Warm-up time of the HeNe laser
min
1
10...20
Horizontal and vertical beam distances
mm
12
Pitch and yaw measuring ranges
arcmin
±1.5
Angular resolution at 0.1 nm length resolution
arcsec
0.002
Operating temperature range
°C
15...30
Maximum displacement speed of the measuring reflector
mm/s
800
Dimensions (L x W x H)
Sensor head with adjustable mount
Electronic supply and evaluation unit
mm
mm
142 x 102 x 50
450 x 400 x 150
Mass
Sensor head with adjustable mount
Electronic supply and evaluation unit
kg
kg
2.3
9.5
Interfaces standard
optional
RS232C, USB
Digital 32-bit parallel interface Digital
incremental signals (TTL level)
Analog incremental signals (1VPP)
Cable length between sensor head and electronics unit
m
3, optionally up to 10
Line voltage / frequency
VAC/Hz
100...240 /47...60
Laser safety class according to EN 60825-1:2007 and
ANSI Z136.1 (CDRH)
2M
II