LM-0700 Laser Safety


  • IEC 60825 or ANSI Z136

  • Laser Safety Regulations

  • Laser Beam Divergence

  • Laser Intensity

  • Max. Permissible Radiation

  • Safety Distance

  • Damaging Effects

  • Laser Classification

  • Safety Goggles

  • CW and Pulse Laser

LM-0700 Laser safetyLM-0700 Laser safety Set-up

In this experiment the students are encouraged to convert the essential theoretical contents regarding „Laser Safety“ into practice. The application and use of the basics in calculation defined within the standards is submitted and trained by means of practical examples. The major measurement task is to determine the intensity of a laser beam which is defined as power per cross section typically given in W/m². The power is measured by using a calibrated power meter. The cross section and the divergence is determined by a set of imaging lenses with known focal lengths. In addition to the direct exposition also the danger of scattered light is classified by using a scatter probe mounted on a pivot arm.
The experiment is divided into several segments. Aspects such as the following ones have been considered:
  1. Determination of the maximum permissible radiation (MPR) for skin and eyes
  2. Minimum safety distance from a radiation source for direct and indirect irradiation of the skin and the eyes, (MSD)
  3. Characterization of a pulsed laser systems
  4. Requirements for laser safety googles, transmission of optical filter
The fundamentals of IEC 60825 or ANSI Z136 or corresponding literature of laser safety should be known. The danger of lasers are understood by the characteristic properties of the laser radiation. In comparison with other light sources a high energy and power density can be attained, because of the generally small beam divergence the radiation density can be very high even at large distances from the laser (potential danger of lasers used in metrology). Not only the direct radiation also reflected and scattered radiation can cause damage at a large distance from the radiation source. Laser radiation can be generated within a broad spectral range. It extends from a few nanometer up to some hundred micrometers and is, in many cases, outside of the visible spectrum. The damage of the biological tissue (skin, eye) depends strongly on the wavelength and on the duration of the exposition. This is of great importance under safety aspects when classifying the lasers and fixing radiation limits which is also subject of this experiment. By means of two different laser sources all parameters are measured in order to classify each laser and to determine the limits for which the laser can be considered as save. This includes also the characterization of laser safety goggles.

Principle of Measuring the Laser Divergence
A. Principle of Measuring the Laser Divergence
To determine the maximum permissible radiation (MPR) the laser safety officer needs to know the wavelength, the beam diameter, laser power and finally the mode of operation, if pulsed or continuous mode. To get the MPR from the tables of the laser safety regulations one needs to know the laser intensity in W/m2. The continuous laser power in watt or milliwatt is measured by a calibrated power meter. Dividing the measured value by the beam cross section we get the intensity. In order to determine the MPR in a defined distance, the officer needs to know in addition the divergence of the laser. Due to the large divergence of the pulsed laser it can be measured straight forward by using the goniometer. For the green laser with a much smaller divergence this method fails. That is why we need to increase the divergence first by using a lens (BCL) with known parameter. By using the ABCD parameter, the divergence of the laser source can be calculated backwards based on the measured divergence behind the lens. Such a measurement example is shown in Fig. B.
Measured Laser divergence
B. Measured divergence
LM-0700 Laser safety, consisting of:
Item Code Qty. Description
1 CA-0220 1 Multimeter 3 1/2 digits
2 DC-0050 1 Pulsed laser diode controller MK1
3 DC-0120 1 Si-PIN Photodetector, BPX61
4 DC-0380 1 Photodetector Junction Box ZB1
5 LQ-0020 1 Green (532 nm) DPSSL in ø25 housing
6 LQ-0350 1 Pulsed diode laser in housing
7 MM-0020 3 Mounting plate C25 on carrier MG20
8 MM-0060 1 Filter plate holder on MG20
9 MM-0090 1 XY adjuster on MG20
10 MM-0300 1 Carrier with 360° rotary arm
11 MM-0340 1 Scatter probe on rotary table
12 MM-0420 1 Four axes kinematic mount on carrier MG20
13 MP-0150 1 Optical Bench MG-65, 500 mm
14 OC-0010 1 Biconcave lens f=-10 mm, C25 mount
15 OC-0170 1 Collimator 808 nm in C25 mount
16 OC-0939 1 Filter BG39, 50 x 50 x 3 mm
17 UM-LM07 1 Manual Laser Safety
Required Option (order separately)
18 CA-0200 1 Oscilloscope 100 MHz digital, two channel
19 CA-0260 1 Laser power meter LabMax-TO
20 CA-0262 1 Energy sensor head 300 nJ - 600 µJ
21 CA-0264 1 Power sensor LM2 VIS 50 mW / 1 nW
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