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SI-MT/SI-MKB/SI-HTB
WORLD PRECISION IN STRU MENTS
35
signal. To do this, press the
Display
button on the controller to view the signal
amplitude. This shows the detected fi rst order diffraction of the laser pattern. This
amplitude is maximal if the focused light hits the sensitive area of the detector
chip. To keep the signal from saturating the CCD and giving erroneous signals,
adjust the amplitude so that it is as close to 3.0V as possible. Using the
Laser
Power
knob on the controller and the
Camera X-Y Adjustment Knob
, you
can precisely position the CCD camera and control the laser power so that a
desirable signal is achieved.
Calibrating the Camera
Your Sarcomere Length Unit comes with several calibration gratings. These are clear
plastic fi lms with an embedded grid (Fig. 34). When exposed to the laser, the grating acts
in place of the muscle to create a consistent diffraction pattern that is used to calibrate
the camera.
Fig. 34 (Left) The sarcomere grating fi ts into the cuvette and provides a foolproof calibration
method.
Fig. 35 (Right) The grating is position in the optical cuvette to calibrate the camera.
1. Turn on the system. See "Turning the System On" on page 25.
2. Enable the Laser. For safety reasons, the laser is always disabled on startup. See
"Turning On/Off the Laser" on page 32. When the laser is enabled, a red dot (the
laser beam) appears near the cross hair mark on the front of the camera.
3. Position a calibration grating inside the optical cuvette so that the laser beam shines
through the grating and casts a diffraction pattern on the camera lens (Fig. 35).
4. Adjust the zero order laser spot (the center beam) so that it hits the cross hair mark
on the camera. See "Aligning the Laser and the Camera" on page 33.
5. Using
the
Camera Height Adjustment Knob
and the
Laser Power Knob
on the con-
troller to display the ideal signal for the fi rst order signal.
6. Read the sarcomere length on the LCD display.
7. Use
the
Camera X-Y Adjustment Knob
to adjust the horizontal position control on
the camera until the sarcomere is displayed at 2.0µm.