The Bioptechs Objective Heater is a system specifically designed to safely and accurately warm the objective of a microscope to prevent heat loss from the specimen when using immersion lenses. There are two main components, are the electronic controller and the objective heating attachment. The Bioptechs Objective Heater System is the only objective heating system that incorporates the thermal profile of the objective into the temperature control loop and regulates the objective temperature to the specimen plane where it belongs!
The Problem: When live-cell imaging requires the use of high numeric aperture lenses, it is necessary to control the temperature of the objective as well. This problem exists because the optical coupling medium (oil, glycerin or water) acts as a thermal coupling medium and draws heat away from the specimen. The thermal mass of a fluid coupled objective is overwhelming when compared to the thermal mass of the cells. Unfortunately microscope manufacturers do not offer temperature controlled objectives; nor do they consider the need for thermal regulation in the design of their objectives. Bioptechs has developed and patented a product that solves this problem for the majority of immersion objectives.
The Solution: To eliminate this thermal gradient, Bioptechs offers a patented Objective Heater® System which includes a heater/sensor and an electronic controller. The heater/sensor is comprised of an adjustable thin-film heating band which surrounds 3/4 of the diameter of the upper region of the central retracting tube of the objective. A surface probe thermal sensor positioned in the gap formed between the ends of the heating band measures the temperature of the objective. This heater/sensor assembly is supported on an adjustable metal mounting to fit objectives ranging from 14 to 37mm in diameter. (Diagram) The heater loop requires a minimum of 3.5 to 6mm longitudinal, physical contact with the cylindrical objective surface depending on which objective heater is required. In some cases there may be a decorative collar on the objective that must be removed in order to permit adequate surface contact. Depending on the objective, it may be necessary to invert the objective heater and mount the objective upside down for optimal thermal transfer to the lens of the objective. It may also be necessary to isolate the objective from the nosepiece turret for proper objective temperature regulation. Thermal Spacers are available from Bioptechs to reduce the heat sinking effect of the nosepiece and the other objectives on it. The Controller is specifically designed to slowly heat the objective over a fifteen minute warm-up period then hold the objective at the set point value within 0.2 degrees C. The Controller operates from ambient to 50 degrees C and has special safety circuitry which utilizes a 0.9 degrees C error window to shut down the controller and sound an alarm if, for any reason, the temperature of the objective deviates after it has reached set point. A user calibration test is also built in to the controller.
Objective Wrench and Pliers – 1178K44
In order to expose sufficient surface for mounting heat transfer devices on some manufacturers’ objectives, it is necessary to remove the outer decorative collar which contains written information such as magnification, N.A., etc. The objective wrench is designed to enable the user to isolate the mechanical stress applied to an objective when removing this collar. The rotational force applied to the objective must be applied exclusively to the mounting threads and the cover and not to the internal optics or the spring loaded retracting casing. The wrench is designed with two thread sizes (0.8" x 36 TPI (RMS) and 25mm x 0.75 mm/thread). It will enable the user to isolate the force necessary to remove the outer sleeve from the core of the objective by securely binding on the external threads of the objective and provide sufficient leverage for removal of the cover.
Thermal Isolator
The Bioptechs’ Thermal Isolator is a device made of a material having a low thermal conductivity and mounts between the objective and nosepiece used to reduce heat exchange between the objective and nosepiece. It is used when cooling objectives below ambient temperatures. It also contains a two sided AR coated window and gas ports through which dry air is introduced to prevent condensation.
RMS (0.8" x 36 tpi) – 1178K45
25mm x 0.75mm – 1178K46
27mm x 0.75mm – 1178K47
Thermal Spacer
The Bioptechs’ Thermal Spacer is a device made of a material having a low thermal conductivity and mounts between the objective and nosepiece used to reduce heat exchange between the objective and nosepiece. It is used when heating objectives above ambient temperatures. It will enhance the thermal transfer efficiency of the objective heater.
RMS (0.8" x 36 tpi) – 1178K48
25mm x 0.75mm – 1178K49
27mm x 0.75mm – 1178K50
9mm Stage Lift Kit – 1178K51
Both the Thermal Isolator and Thermal Spacer will add 9mm to the height of the objective. Therefore, it is necessary to elevate the stage by the same amount. The Bioptechs stage spacer kit contains 4, 9mm spacers and longer screws to raise the position of the stage. When the height of a microscope stage is modified to accommodate the addition of a Thermal Isolator or Thermal Spacer to one of the objectives, it is recommended to add spacers to all the other objectives on the turret to keep them parfocal.
Objective Cooling Collar – 1178K52
The Objective Cooling Collar is an attachment to an objective that provides an isolated pathway through which a refrigerated fluid can flow. This provides an efficient means of cooling the objective. The source of the chilled fluid can be as simple as a dewar of ice water or as sophisticated as an AC powered recirculating chiller bath. The removal of heat from the objective is more difficult than heating because you are limited by the thermal transfer efficiency of both the objective and the contact surface of the cooling ring. Therefore, the cooling ring needs to be of sufficient size and contact surface to work. It is advisable to make sure you have enough room under the stage for the additional diameter required for the cooling collar and tubing. Cooling collars are precision machined to fit specific objectives.