Objective Heater System Instructions

The Bioptechs Objective Temperature Control System is comprised of two components. One part is the electronic controller unit; the other is an adjustable objective heater loop which attaches to the microscope objective. The objective heater is designed to mount onto oil immersion objectives. To eliminate the heatsink effect that is accelerated by the presence of oil or water as an optical coupling medium. These objectives have a retractable central tube which contains the optical elements.  Heat is directly transferred to this tube and sensed by a thermistor which is part of an intelligent feedback control loop.  The heater loop requires a minimum of 5mm longitudinal physical contact with the cylindrical objective surface.  In some cases there may be a decorative collar or sleeve on the objective which must be removed in order to permit adequate surface contact for the heater loop.  (See illustration – outer sleeve removed)

Specifications

Directions

PLEASE READ BEFORE USING THE BIOPTECHS, INC. OBJECTIVE HEATER!

Objectives are expensive and delicate.  We recommend following the directions below carefully.  Although great care has been taken to produce a reliable product to control the temperature of your objective, there is always some risk.  BIOPTECHS, INC. assumes no responsibility for use of this or any other objective heater.  The user assumes all liability for any damage that may occur due to the use of this objective heater.

Objective Controller

The controller can operate between 90 - 260V 50-60Hz.  The AC power line input, power switch, voltage selector, and fuses are all incorporated on the rear panel.  The fuse carrier contains two 0.5A slow blow fuses.  The fuses can be accessed by prying the fuse block out of its socket with a small screwdriver wedged under the small slot in the opening of the AC line receptacle.  When replacing the fuse block, make sure to align the arrow on the outside of the fuse block with the closest supply line voltage:

§         For 90-130 supply line voltage place the fuse block with the arrow pointing to 110-120V.

§         For 180-260 supply line voltage place the fuse block with the arrow pointing to 220-240V.

Controller Operation:

1.       Turn the unit on using the main on-off switch located on the rear panel.  All further adjustments are made on the front panel.  DO NOT plug in the objective heater at this time.

2.       Turn the display switch to the "OBJECTIVE" position.  The temperature display will read a number between -3.7 and -4.2.  This is normal.  Press the black button labeled "CALIBRATE" and make sure the display reads 25.0°C.  If adjustment is necessary, turn the screw in the hole labeled "OBJECTIVE" with the enclosed screwdriver.  CW = increase, CCW = decrease.

3.       Set the display switch to the "SET" position, then insert the enclosed screwdriver into the hole marked "SETPOINT" and adjust the controller 1.8° less than the desired setpoint to compensate for the thermal characteristics of the objective.

4.       Turn the controller OFF.

5.       Mount the objective heaterband onto the objective.  (See illustration – assembled objective heater)

6.       Plug the objective heater into the controller then turn the controller ON.

7.       IMMEDIATELY set the display knob to the objective position and check that it is indicating a value between ambient and setpoint.  If the temperature value displayed is not realistic turn the controller off immediately.  (Other values indicate possible damage to the temperature probe).  As a safety feature, when the sensor temperature reaches setpoint minus 0.9°C an internal latch is set.  Then if the temperature of the sensor falls below 0.9°C less than setpoint, an alarm will sound and the heater current will be shut off.  The controller will still be on but the output disabled.  If the red reset button located next to the red LED is pressed it will return the controller to cold startup mode and current will return to the heaterband.

8.       Always make sure the sensor is in direct contact with the objective.  When you press the reset button, the controller always enters cold startup mode and ignores out of range conditions.  Therefore it is important that the objective heater is installed properly.

9.       The objective will come up to temperature in about 5 to 10 minutes.  The controller will maintain a constant temperature relative to the value of the contact probe.  However, it may be necessary to fine-tune the setpoint adjustment for your particular objective.  The temperature of the upper element of the objective should be monitored with an independent thermal sensor to establish the correct setpoint value.

Heater Installation:  (The heater band should be unplugged from the controller and the controller shut OFF)

1.       With the objective secured in the nosepiece of the microscope hold the heater assembly upright with the loop in a superior position. (See illustration – assembled objective heater)

2.       Insert the enclosed 2mm Allen screwdriver into the hole in the top of the metal enclosure.  Rotate the Allen screwdriver clockwise to allow the loop to expand to fit various objectives.  Please note that it may be necessary to gently withdraw the black heater band from the metal enclosure to relieve the slack in the tensioning mechanism.  DO NOT place tension on the red wires.

3.       Place the heater loop over the exposed cylindrical end of the objective closest to the specimen making sure the band is evenly applied to this area and that the temperature sensor is also making direct contact with the objective.

4.       Tighten the heater loop onto the objective by turning the Allen screwdriver counterclockwise until the loop is snug.  Use only enough pressure to cause the heater to conform to the objective diameter and uniformly compress the temperature sensor to the objective.  DO NOT OVER TIGHTEN the loop as damage will occur to the tensioning mechanism.

5.       There is a slight mechanical offset to the temperature sensor to maintain contact which may cause the tension mechanism to rise slightly.  It may be necessary to restrict this movement with an elastic band.

6.       Plug the Objective Heater band into the Controller then turn the controller ON.  (Refer to step seven above)

Note:  To reduce the possible detrimental effects of temperature cycling, it is recommended that the objective be kept in a warming box when not in use.

©Bioptechs, Inc., 11/2/00
BNi04200302