12
Movement and positioning module
is intended for precise positioning of the thermal unit
within 140 mm in horizontal plane, which provides easy access to the tubes.
The hot lid module
provides a reliable heat contact between tubes and the thermal plate and
allows maintaining temperature of the tube caps at the level of 105±1°С in order to prevent
condensate formation on the tube caps, since it may cause substantial distortions in the lumi-
nous flux measurements. The hot lid design provides an adjustable force of tube-to-plate hold-
down that depends on the number of the tubes installed. During running PCR the thermal
block moves vertically from bottom to top. The moment of contact of the tubes with the hot
lid is monitored by a special sensor, which passes information to electronic module of the in-
strument to calculate the necessary pressing force. The positioning module moves the thermal
block vertically by an amount that provides the necessary pressure to hold the tubes against
the surface of the hot lid.
2.3 Optical system
The optical system consists of an optical module and a light beam transmission module.
The optical module
is a system of lenses, mirrors and light filters that provides folding of the
luminous flux from several light sources on one optical axis and its separation from the lumi-
nous flux entering the CCD camera. The light sources are powerful LEDs. The light source
design provides efficient heat removing from emitting crystals of the light-emitting diodes for
stable luminous flux.
Optical path
(
light beams transmission module)
ensures the transmission of the luminous
flux from light sources of the optical module to the tubes, and back transmission of the fluo-
rescent luminous flux from the tubes to CCD camera.
The module for light beams transmission is a rectangular duct. Rectangular mirrors located in
the duct corners provide the optical pathway in a required direction.
The system of light locks provides an absolute isolation of the optical channel from external
light.
The calibration curve of the optical channel (the dependence of the measured fluorescence
intensity on fluorophor concentration) is linear in the range of the quantity of matter of stand-
ard fluorophor from 0.05х10Е-12М up to 0.2х10Е-12М.
2.4 Control and display system
The control and display system comprises a push-button panel for manual control of the ther-
mal block movement and the LCD screen indicating the process of amplification program
running (Fig.3).
