PerkinElmer RamanStation 400, Getting Started Manual

Page: 23 / 118

Safety Practices .
23
Where:
f
o
= Probe focal length (cm)
b
o
= Diameter of laser beam incident on probe focusing lens (mm)
Φ
= Total radiant output power of probe (watts)
MPE =
Maximum permissible exposure (J cm
−2
)
For a Raman probe
b
o
is 0.254 cm, therefore the above equation can be simplified to give:
2
1
. 442 . 4





 Φ
=
MPE
f NOHD
o
For the wavelength range 700 – 1050 nm the
MPE
for a 10 second exposure can be
calculated from:
( )
( )
( )
[ ]
4 7 . 0 2
10 10 1 . 10
− − =
λ
MPE
J cm
−2
Where
λ
is the laser wavelength in micrometers ( µ m). For example, a laser wavelength of
785 nm (0.785
µ
m) will have an
MPE
value of 1.49 × 10
−2
J cm
−2
or 1.49 × 10
−3
W cm
−2
for
a 10 second exposure or longer. The table below shows the calculated nominal ocular hazard
distance for 785 nm Raman systems.
Probe focal length/mm NOHD for 100 mW exiting fiber optic probe/cm
7.5 (± 10%) 27.3
Table 2 Nominal Ocular Hazard Distance (NOHD) for 785 nm
NOTE: Other focal lengths are available; contact PerkinElmer for details. In particular, the
use of an ultra-long working distance lens adaptor (part number L1320071) provides
a working distance of 25 mm. Where different focal lengths are used, the NOHD
should be calculated accordingly.
Internal Interlock System
There is an interlock system associated with the sample compartment lid (Figure 4). If the
door is open then the laser cannot be emitted from within the instrument without deliberate
user intervention.
The interlock switches cannot be over-ridden by using simple magnets. The placing of a
specifically coded magnetic actuator (MA) in the vicinity of a magnetic proximity switch (MPS)
may disable the interlock and allow laser light to be emitted from the instrument. Placing a
specifically coded magnetic actuator (MA) in the vicinity of this magnetic proximity switch
(MPS) is not recommended under any circumstances and is considered highly dangerous,
compromising the safe operation of the instrument. This type of action is deemed to be a
deliberate attempt to bypass the internal instrument safety interlocks and as a consequence
of this the instrument will be classified as Class 3B.