BeamMonitor

Measuring device for the characteristics of the unfocused laser beam

The CameraMonitor 10.6 is a camera-based measuring system analyzing IR laser radiation at 10,6 µm wavelength.

  • Determinatoin of beam width and beam position based on the measured power density distribution
  • Intuitive grahical user interface
  • High dynamic due to a 14 bit A/D
  • Quartz-stabilized motor drive of the rotational axis
  • Power range 100 W - 20 KW
  • power density range 100 W/cm2 - 10 kW/cm2 >20kW
  • Different apertures matched to the applications between 40 mm and 100 mm

Application

The laser beam is scanned with a rotating mirror So a small part of the beam is faded-out and directed to the detector.During the motion of the mirror the incoming signal is digitized and transmitted to acomputer. The position of the scanning track is changed by a linear motion in y- direction. The 12 bit A/D- converters and a resolution of 128x256 pixel enables an exact analysis of even small pertubations. operation laser-induced variations of the beam parameters cause a decrease of processing quality and velocity. The exact analysis of the true reason is ordinarily rather complicated, since other phenomena like variation of the focal position or the nozzle's adjustment have similar errors. At this point a detailed analysis of the'raw' laser beam between outcoupler and focussing optics is a reliable method to detect variations of the beam diameter, bad mode-structure or wrong beam position.

With the BeamMonitor from PRIMES the customer gains the opportunity of quick and reliable diagnostics of the beam parameters. The BeamMonitor is a device to determine the spatial power density distribution of high power CO2- und Nd:YAG - Lasers.

The beam diameter and position are calculated from these data.

Technical description

The laser beam is scanned with a rotating mirror So a small part of the beam is faded-out and directed to the detector. During the motion of the mirror the incoming signal is digitized and transmitted to acomputer. The position of the scanning track is changed by a linear motion in y- direction. The 14 bit A/D- converters and a resolution of 128x256 pixel enables an exact analysis of even small pertubations.The device is designed for operation in rough industrial environments.

Technical data

BeamMonitor 40 mm


Beam Data to be acquired

  • Maximum power density (cw): dependent on scanning mirror design up to 10 kW/cm2
  • Clear aperture: 40 mm
  • Maximum beam radius (86 % = 1/e2): approx. 12.5 mm

Measurement System

  • Function: Two - dimensional scanner to determine power density distribution of the laser beam in x- and y plane by scanning a partial beam due to a rotating mirror. The complete beam transversed the device and needs to be trapped during the measurement cycle.
  • Dimension of the scalable measurement window: Range from 3.3 x 3.4 to 40.0 x 40.0 mm with a scaling factor of approx. 1.4
  • Spatial resolution: towards x (# of measured dots per track) 32, 64, 128, 256; towards y (# of tracks per image) 32, 64, 128
  • Mirror driver for x - axis: maintanance - free brushless DC - driver with quartz - stabilized speed - control.
  • Mirror driver for y - axis: Driver with absolute encoder and ball screw spindle
  • Measurement data digitizing: 14 - bit AD - converter
  • Measurement cycle: Standard measurement window with resolution of 64 x 64 (4096 dots): 2.5 s ; repetition rate approx. 0.2 Hz

Power supply and communication bus

  • Electrical power supply: 24 V DC ± 5 %
  • Current consumption: max. 1.8 A; standby consumption 0.4 mA
  • Electrical connectors: 2 x PRIMES - RS485 - bus D - sub - min
  • Communication: The incoming RS 485 bus - signal will be converted for the serial PC COM port. The PRIMES software with graphical - user - interface operates under Windows operating systems, like WIN 95/98, NT, WIN 2000, XP

Mechanical Dimensions

  • Dimensions (LxWxH): 243 mm x 146 mm x 76 mm ( plus connector)
  • Weight: 2,6 kg

Software

  • measuring results: beam radius (86 % and 2. moment), beam position, power density distribution, beam propagation factor M2
  • Modes: Single plane measurement, averaging, monitoring
  • Presentation: Isometry, false color, graphical cut, data table.
  • Formats: storage of PRIMES *.foc files or ASCII

BeamMonitor Options

  • Measuring at a fix y-position


Control and presentation

Control is realized by different user specific solutions such as: graphical user interfaces in Microsoft WINDOWSTM availiable as well as a direct connection to a SPC.For interface to a PC or SPC, the built in RS485- interface is used.The software has the following features:

  • Measurement parameters: beam radius (based on 86 % and 2nd moment calculation), beam position and power density calculated from a given power value in peak and 86 % - radius.
  • Measuring modes: single and serial measurement, temporal development
  • Presentation: Isometry, false color, contour lines and check of symmetry.