Microscopes in general are complex instruments that combine high quality optical components with high precision mechanical parts. All of these pieces must work together in a specific and seamless arrangement in order to achieve optimal performance from the device. Microscopes such as brightfield and fluorescence, come in different configurations to address various needs, whether they be for simple educational use, general research lab use, or high capacity use in a human pathology lab setting. These setups each may have add-ons in addition to matched components in order to extend the function and applications of the device.
There are several types of device setups and illumination configurations. To start, there is the traditional upright microscope, which is commonly used for viewing objects that are large or in suspension, and for applications including metallurgy, cell culture, and for viewing aquatic specimens. Next is the inverted microscope, in which the objectives are oriented upward from the bottom, toward the specimen. The advantages of inverted microscopes include the ability to maintain a more natural environment for the specimen, therefore allowing extended viewing of life processes. This is not possible with compound microscopes, which require thin specimens to be placed under a cover slip where evaporation is prevalent and gas exchange is compromised.
The objectives help dictate the quality and range of a microscope. Interchangeable objectives on a turret provide a significant range of magnifications and certain advantages over fixed objective devices, which may be charged with a dedicated task such cell counting. Specific models are typically matched with objectives that are optimized for the device design, and therefore the objective and/or turrets are not meant to be exchanged. Consequently, as the magnification needs change, the microscope will need to be upgraded as well.
Beside the objectives, the next important feature to consider is the illumination system.
Brightfield illumination sources can include halogen lamps or LEDs, depending on the application.
Fluorescence illumination is dependent on the excitation parameters of the fluorophores used in the given application. Traditional fluorescence light sources have included either xenon arc or mercury-vapor lamps. Modern technology and applications have fostered the implementation of LEDs as the illumination source of choice. Accordingly, there are many types of external units that can be fitted with a given microscope setup.
Certain types of experiments call for an application called laser microdissection (also known as laser capture microdissection). For this technique, a laser light source coupled to the objectives as an attachment is used to target microfine cell and tissue segments for excision or ablation. The user-controlled laser-fitted objectives are guided by software and the microscope platform is designed and optimized specifically for the technique.
Beyond the optics and illumination, the next important feature is the image capture system. Modern microscopes can be fitted with an array of different devices, optimized for the image source and resolution requirements.
- Camera options include: high-resolution, active cooling, high-contrast color, ethernet and USB compatibility, and wireless capabilities, all aimed at capturing the clearest and most useful image information from fixed or live cells and tissue, according to the needs of the user.
Here is a list of a few popular add-on features and replacement parts:
Modern add-ons include the ability to share images on an external device such as a monitor or even a tablet.
Multiple viewing systems allow multiple users to view the sample specimen on the same device. Anywhere from two to twenty binocular viewing stations can be fitted to a compatible device.
As changing the defraction limit of the viewing objective can increase the resolving power of the microscope, systems exist for automatic and controlled release of oil, water, and other liquid dispersion to the objective for immersion viewing. These systems have evolved no less to avoid the inconsistency, mess, and potential for objective damage traditionally associated with the method.
To suit the need to change the orientation or arrangement, or to access certain areas of the specimen, micro-manipulator modules are available in many types and capabilities. Examples include the requirement for stabilizing cells for microinjection of DNA, RNA, or virus, or for the placement of probes during electrophysiology experiments.
A wide variety of stands and stages are available meant to accommodate certain applications. For instance, large samples in which significant scanning of the specimen is necessary requires a modular stand to allow this movement. Others address the illumination, temperature control, and vibration isolation needs of certain applications. Still others are designed for motor controlled movement and motor focus functionality.
Regardless of the application and the operation, budget plays a role in all fields of research, industry, and medicine. Used microscopes and equipment are always an option and manufacturers can offer parts and accessories for this need.