User:Wikiwo
CONTACT-FIELD OPTICAL MICROSCOPE
Everything releases photon energy
[edit]Everything in universe from cosmos dust to human body, organs, living cells and molecules releases photon energy, because absolute zero temperature is not reachable according to the third thermodynamic low.
Energy level of life on earth is in the range from microwave to infrared. Coded energy flow is the fundamental soul of life
Living organisms, running car engines and working microchips release coded photon energy. Dead organisms，shut down car engines and microchips release random photon energy.
Coded energy flow is the fundamental soul of life.
[edit]How to measure the dynamic microscopic image with nanometer resolution of this coded energy flow is one of the most exciting challenge for self-assembly, nanotechnology and nano-medicine.
Water, moisture and CO2 are opaque to infrared.
[edit]Infrared can be detected by infrared sensor but is very strongly interfered by medium such as water, moisture and CO2, because water and CO2 are opaque to infrared.
Far-field optical microscopes (lens equipped) and near-field scanning probe microscopes（scanning tunneling microscopy, atomic force microscopy）
[edit]Traditional optical lens equipped microscopes are based on far-field optics, where the distances between the sample and the detector are much larger than the wavelength of the light source. It is well known that the resolution of the far-field optical instruments is originally determined by E. Abbe barrier, it is not finer than λ/2, where λ is the wavelength of the light source. For visible light, it is only about 200 nm.
Unlike traditional microscopes, scanning probe microscopes are near-field microscopes such as scanning tunneling microscopy, atomic force microscopy and near-field scanning optical microscopy, the techniques to overcome the diffraction limit, do not use lenses, so the size of the probe rather than diffraction effects generally limit their resolution. All of these microscopes work by measuring a local property - such as tunneling current, height, optical absorption, or magnetism - with a probe or "tip" placed very close to the sample.
Both of these two kinds of microscopes can not decrease the working distance to zero and can not avoid the interference of the medium between sample and image detector. Therefore it is very difficult to monitor the dynamic microscopic functional image with nanometer resolution by both of them.
In an article by Lewis A., et al entitled “Near-field optics: from subwavelength illumination to nanometric shadowing,” Nature Biotechnology 21, 1378 - 1386 (2003) Lewis A. et al described: ”Probably the most exciting application of this sort of external illumination protocol is the imaging of chemical alterations in a sample by monitoring the scattering of infrared radiation within the region of the electromagnetic spectrum where vibrational modes of surface molecules absorb light in chemically specific ways. Such chemical identification with high spatial resolution is very important for numerous areas of interest in biology. These extend from the chemical identification of molecular entities on biochips to the spatially resolved nanometric imaging of highly compartmentalized cell membranes. Of course, application of this latter methodology to biological imaging is subject to the problem of high absorption of infrared radiation by water”.
Although electron microscopes offer very fine resolution, the specimen must be prepared by high-vacuum dehydration and is subjected to intense heat by the electron beam, making observation of living specimens impossible. The dehydration process also alters the specimen, leaving artifacts and sample damage that were not present in nature.
Sample optical image can be magnified by Tapered optical fiber bundle.
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Comparison of lens (right) and fiber optical taper magnifier (left)
Third generation of microscope: Contact-field optical microscope
[edit]A contact-field optical microscope is equiped with an optic taper sampling face(102) in contact with a sample surface(101) (zero working distance) as sample image pre-magnifier. Therefore, the medium interference between sample and image detector can be avoided. The optic taper pre-enlarged image is converted to photon-electron image by photocathode in vacuum chamber. The photon-electron image is further enlarged by electro-magnetic lens, enhanced by micro-channel plate and displayed on phosphor screen.
The gain of the microchannel plate (MCP 112) is adjustable over a wide range with a typical maximum of about 80,000 (a detected photon at the input leads to a pulse of 80,000 photons from the phosphor screen).
It is useful to provide a microscope that can adjust photon input flux density by changing the gain of the micro-channel plate to satisfy different radiation from the sample, especially for the measurements of very weak living cell radiation.
The photocathode is responsive to photons of visible and infrared light of an image of a sample to liberate photoelectrons which are moved by a prevailing electrostatic field to a microchannel plate causing a geometric cascade of secondary-emission electrons moving along the micro channels, from one face of the micro channel plate to the other so that a spatial output pattern of electrons (which replicates the input pattern; but at an electron density which may be, for example, from one to several orders of magnitude higher) issues from the micro channel plate. This pattern of electrons is moved from the micro channel plate to a phosphorescent screen by another electrostatic field. When the electron shower from the micro channel plate impacts on and is absorbed by the phosphorescent screen electrode, visible-light phosphorescence occurs in a pattern which replicates the image.
The spectrum of the contact-field optical microscope can be extended from infrared to visible light, X-ray and charged particles by changing the chemical composition of the fiber core glass(204).
Detail see contact-field optical microscope