Microscope objectives

The high index of refraction and dispersion properties of its oxide s have made germanium useful as a component of wide-angle camera lenses and microscope objectives. 

If the detected frequency of the flashing light scattered by a microscopic object when crossing the fringes is multiplied by the fringe distance, the veltKity component of the scattering object normal to the beam bisector and parallel to the laser beam plane is determined. 

Figure 4.6 shows an apparatus for the fluorescence depolarization measurement. The linearly polarized excitation pulse from a mode-locked Ti-Sapphire laser illuminated a polymer brush sample through a microscope objective. The fluorescence from a specimen was collected by the same objective and input to a polarizing beam splitter to detect 7 and I by photomultipliers (PMTs). The photon signal from the PMT was fed to a time-correlated single photon counting electronics to obtain the time profiles of 7 and I simultaneously. The experimental data of the fluorescence anisotropy was fitted to a double exponential function. 

Figure 4.6 Block diagram of the apparatus for the fluorescence depolarization measurement. The dashed and solid arrows indicate the light paths ofthe excitation pulse and the fluorescence from the sample. OBJ microscope objective, M mirror, L lens, DM dichroic mirror, LP long-pass filter, PH pin-hole, PBS polarizing beam splitter, P polarizer, PMT photomultiplier.

The experimental set-up for the FCS measurement is illustrated schematically in Figure 8.6. A CW Ar laser (LGK7872M, LASOS lasertechnik GmbH) at 488 nm was coupled to a single mode optical fiber to isolate the laser device from an experimental table on which the confocal microscope system was constructed. This excitation laser light transmitted through the optical fiber was collimated with a pair of lenses, and then was guided into a microscope objective (lOOX, NA 1.35, Olympus). 

Piller, H. A Universal System for Measuring and Processing and the Characteristic Geometry and Optical Magnitudes of Microscope Objects, in ADVANCES IN OPTICAL AND ELECTRON MICROSCOPY, Barer. R. and Cosslett, V.G., Ed., 1973, 5, 95-114, Academic Press, New York. 

The advantage of Raman spectromicroscopy is that very small specimens can be studied while still allowing the determination of the second and fourth moments of the ODF. However, the expressions for the Raman intensities are more complex since the optical effects induced by the microscope objective have to be considered. Although the corrections may be small, they are not necessarily negligible [59]. This problem was first treated by Turrell [59-61] and later by Sourisseau and coworkers [5]. Turrell has mathematically quantified the depolarization of the incident electric field in the focal plane of the objective and the collection efficiency of the scattered light by high numerical aperture objectives. For brevity, only the main results of the calculations will be presented. Readers interested in more details are referred to book chapters and reviews of Turrell or Sourisseau [5,59,61]. The intensity in Raman spectromicroscopy is given by [59-61]... 

In the papers referenced above it has been shown that depth resolutions around 2-3 pm collected with a 100 x microscope objective are possible. However, the depth resolution will degrade as one probes deeper into the sample this is a consequence of refraction caused by refractive index changes at the sample surface and boundaries within the sample. The greater the depth probed, the greater the dof becomes if an air objective is used the situation can be improved and aberrations minimised if an oil immersion objective is used [16,17],... 

According to Galilei, the observation of natural phenomena using suitable measuring instruments provides certain numerical values which must be related to one another the solution of the equations derived from the numbers allows us to forecast future developments. This led to the misunderstanding that knowledge could only be obtained in such a manner. The result was deterministic belief, which was disproved for microscopic objects by Heisenberg s uncertainty principle. On the macroscopic scale, however, it appeared that the deterministic approach was still valid. Determinism was only finally buried when deterministic chaos was discovered. 

The laser beam is focussed on the sample surface using a microscope objective, and the signal is taken on axis through the same objective. An optical digital microscope allows for the visual inspection of the sample during the measurement the sample is mounted on a three-axis motorised stage, controlled by a personal computer, for adjustment of the focusing position. 

Materials required Pollens were collected from the green house or in nature, light microscope, object glasses, Petri dishes. 

Materials required OCT setup, Tradescantia pallida (Rose), microscope, object-plates, cover glasses. 

Material required Luminescent microscope, object glasses (slices)... 

Apparatus to investigate the fluorescence characteristics of microscopic objects. Patent of England 2.039.03 R5R.CHI. 

To determine optical damage in bulk benzil crystals a Q-switched Nd YAG laser with 1KW peak power, pulse width of 0.1 ps and pulse repetition rate of 500Hz was used. The laser power was attenuated using a set of neutral density filters and focussed onto a bulk benzil crystal using a x10 microscope objective. No optical damage was observed with optical intensities of upto 100MW/cm - Also, no optical damage was observed in benzil cored fibres with similar optical intensities. 

The first fluorescence correlation spectroscopy experiments were carried out several decades ago,62 64 but the general use of the technique was made possible with the introduction of lasers with high beam quality and long-term temporal stability, low noise detectors, and high-quality microscope objectives with high numeric apertures.58,63 The most common set-up is using a confocal inverted epi-fluorescence... 

Abramowitz M, Spring KR, Keller HE, Davidson MW (2002) Basic principles of microscope objectives. Biotechniques 33 772 781... 

Achromat Microscope objective that is designed to limit the effects of chromatic and spherical aberration. Achromatic objectives are corrected to bring two wavelengths of light (typically red and blue) into focus in the same plane. 

Apochromat Microscope objective that has better color correction than the much more common achromat objectives corrected chromatically for two wavelengths of light (red and blue). Apochromatic objectives are corrected chromatically for three colors (red, green and blue) and spherically for two colors, which practically eliminates chromatic aberration. 

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