Bristol 621 - Alignment of Laser Under Test

Model 621 User’s Manual LASER INPUT – IR AND MIR VERSIONS
Bristol Instruments, Inc. 14
Alignment of Laser Under Test
This instrument is a Class 2 Laser Product. It contains a laser that emits radiation
that can seriously damage your eyesight. Less than 15 W of this laser light is
emitted from the fiber-optic connector of the VIS and NIR versions,
and less than 50 W of this laser light is emitted from the aperture of
the IR and MIR versions. Do not stare into this beam or view it
directly with an optical instrument. The Class 2 warning label, shown
here, is located next to the fiber-optic input coupler (VIS and NIR) or
the input aperture (IR and MIR) on the front panel of the model 621.
Maximum safe input is 10 mW of optical power. Laser input power in excess of 10 mW
can result in damage to the instrument.
The laser under test enters the IR and MIR versions of the 621 system through an input
aperture on the front panel of the instrument (Figure 4.2).
Figure 4.2: Front Panel of the IR and MIR Versions
To facilitate alignment of the laser under test, the internal HeNe reference laser is emitted
from the input aperture as a weak visible tracer beam. This tracer beam defines the
optical path of the HeNe reference laser through the instrument’s Michelson
interferometer. In order to achieve the specified wavelength measurement accuracy, the
laser under test must follow exactly the same path.
To block the red tracer beam from exiting the instrument, the input aperture is equipped
with a manual shutter. The input aperture is open when the shutter slide switch is in the
right-most position. The input aperture is closed when the shutter slide switch is in the
left-most position.