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.
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 17 to 35mm in diameter.
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.
Additional options are available for your objective which can help you heat the objective more efficiently, or perhaps if you would like to cool the objective that option is also available.
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.
Thermographic image of a Bioptechs Objective Heater
Visible light image of a Bioptechs Objective Heater
If you have an objective that you are not sure how to heat you have a few options:
- You can check this list for your objective and take note of the proper band size to fit your objective.
- You can use this reference page to measure your objective and select the appropriate heater yourself.
- You can send your objective into Bioptechs to have it sized, photographed and thermally profiled.
If your objective has a decorative collar which prevents an efficient heat transfer, it will need to be removed. You can do this yourself with the aide of a special objective wrench and plier set available from Bioptechs or send in your objective and Bioptechs will remove it for free!
Wrench and Pliers
Used to remove a decorative collar from an objective
8mm Stage Spacer Kit
Used to raise the stage of the microscope up 8mm to accommodate for a thermal spacer
Used to cool the objective