The laser microtome is an instrument used for non-contact sectioning of biological tissues or materials. It was developed by the Rowiak GmbH, a spin-off of the Laser Centre,

Hannover Hanover (; german: Hannover ; nds, Hannober) is the capital and largest city of the German States of Germany, state of Lower Saxony. Its 535,932 (2021) inhabitants make it the List of cities in Germany by population, 13th-largest city in Germa ...

. In contrast to mechanically working

microtome A microtome (from the Greek ''mikros'', meaning "small", and ''temnein'', meaning "to cut") is a cutting tool used to produce extremely thin slices of material known as ''sections''. Important in science, microtomes are used in microscopy, allow ...

s, the

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fir ...

microtome does not require sample preparation techniques such as freezing, dehydration or embedding. It has the ability to slice tissue in its native state. Depending on the material being processed, slice thicknesses of 10 to 100 micrometers are feasible.

Principle

The cutting process is performed by a

femtosecond A femtosecond is a unit of time in the International System of Units (SI) equal to 10 or of a second; that is, one quadrillionth, or one millionth of one billionth, of a second. For context, a femtosecond is to a second as a second is to about 31. ...

laser, emitting

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...

in the

near-infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...

range. Within this

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tro ...

range, the laser is able to penetrate the tissue up to a certain depth without causing thermal damage. By tight focusing of the laser radiation, intensities over 1 T W/cm² (1 TW = 10¹² watts) arise inside the laser

focus Focus, or its plural form foci may refer to: Arts * Focus or Focus Festival, former name of the Adelaide Fringe arts festival in South Australia Film *''Focus'', a 1962 TV film starring James Whitmore * ''Focus'' (2001 film), a 2001 film based ...

. These extreme intensities induce nonlinear effects and optical breakdown occurs. This causes the disruption of the material, limited to the focal point. The process is known as photodisruption. Due to the ultra short

pulse In medicine, a pulse represents the tactile arterial palpation of the cardiac cycle (heartbeat) by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed near the surface of the body, such as at the nec ...

duration of only a few femtoseconds (1 f s = 10⁻¹⁵ seconds) there is only very low

energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...

of a few nano

joule The joule ( , ; symbol: J) is the unit of energy in the International System of Units (SI). It is equal to the amount of work done when a force of 1 newton displaces a mass through a distance of 1 metre in the direction of the force applied ...

s (1 n J = 10⁻⁹ joules) per laser pulse deposits into the tissue. This limits the interaction range to diameters below one micrometer (1 μm = 10⁻⁶ meters). Out of this range there is no thermal damage. Moved by a fast scanner, the laser beam writes a cutting plane into the sample. A positioning unit moves the sample simultaneously, so that the sample can be processed within a short time.

External links

Laser microtomy: opening a new feasibility for tissue preparation
by Holger Lubatschowski, ''Optik and Photonik'' 2(2):49–51, June 2007. {{DEFAULTSORT:Laser Microtome Medical equipment de:Mikrotom#Laser-Mikrotom

Principle

See also

External links