disadvantages of light microscopes?

Answer 1

Dark field microscopy is an optical microscopy illumination technique used to enhance the contrast in unstained samples. It works on the principle of illuminating the sample with light that will not be collected by the objective lens, so not form part of the image. This produces the classic appearance of a dark, almost black, background with bright objects on it.


[edit] The light's path

Diagram illustrating the light path through a dark field microscope.Light enters the microscope for illumination of the sample.
The condenser lens focuses the light towards the sample.
A specially sized disc, the "patch stop" blocks some light from the sample, leaving an outer ring of illumination.
The light enters the sample. Most is directly transmitted, while some is scattered from the sample.
The scattered light enters the objective lens, while the directly transmitted light simply misses the lens and is not collected.
Only the scattered light goes on to produce the image, while the directly transmitted light is omitted

Advantages and disadvantages
Dark field microscopy is a very simple yet effective technique and well suited for uses involving live and unstained biological samples, such as a smear from a tissue culture or individual water borne single-celled organisms. Considering the simplicity of the setup the quality of images obtained from this technique is impressive.

The main limitation of dark field microscopy is the low light levels seen in the final image. This means the sample must be very strongly illuminated, and can cause damage to the sample.

Dark field microscopy techniques, due to the simplicity of the setup, are almost entirely free of artefacts. However the interpretation of dark field images must be done with care as common dark features of bright field microscopy images may be invisible, and vice versa.


[edit] External links and references
http://www.microscopyu.com/articles/stereomicroscopy/stereodarkfield.html

Retrieved from "http://en.wikipedia.org/wiki/Dark_field_microscopy"

hope u benefit

Answer 2

light microscopes have several distinct disadvantages:

Primarily both the resolution and enlargement factor are much lower than higher tech microscopes being typically x400 magnification on a light microscope and anything up to x2000 on an electron microscope. They can only view the surface of a specimen, as a pose ,for example, to a Transmission Electron Microscope which can penetrate through a specimen. They are also heavily reliant on human experimental technique in the preparation of slides.

Answer 3

I think Pharmalolli has it covered, except for the soical implications - let's face it if you are carrying around a light microscope - like at a party - it's a major social disadvantage, and you are really going to look like a geek. Your social status is helped much more by carrying an iPod or multimedia phone.

Answer 4

light microscopes have a lower magnification and so the sample can only be enlarged to a certain extent. they also have a lower resolution (around 2 micrometres) and so will not distinguish between different cell organelles as an electron microscope would- it would all appear to be one organelle.

Answer 5

light microscopes have a smaller resolution then electron microscopes, this means you see more point to point with an elctron microscope than a optical microscope.

Answer 6

well light microscopes cant zoom in as well as electron microscopes but they are good for viewing live organisms because organisms cant survive in the electron microscopes.

Answer 7

easy microscopes are low fee and fact straight forward instruments while electron microscopes are a lot greater complicated, and supply a a lot bigger decision image and are able to a lot bigger magnification.