Rotating mirror

In the 1930s, Bone et al. [15] using rotating mirror camera observed the action of shock waves propagating into the unburnt mixture ahead of the accelerating flame, and postulated that the detonation wave was initiated as a result of preignition of the shock-compressed mixture. 

Fig. 2.7. Initiation of detonation in explosives, as shown in a rotating mirror camera.

The inset diagram in Figure 22.2 shows the use of a prism in place of the grating . However, underlying principle being identical, a rotating mirror affords the scanning of individual frequencies. 

The main differences when compared to conventional fluorescence microscopes are based on several entities. A laser beam - usually an argon-krypton laser-is used for the illumination of the sample. The focused illuminating beam scans across the specimen by means of rotating mirrors, followed by a point-by-point signal collection which results in a raster sweep of the specimen at one particular focal plane. This is indicated by the term laser scanning. ... 

Karlov etal. investigated inversion kinetics in a pulsed CO2 laser, which was Q-switched with a rotating mirror, by shifting the time delay between excitation and Q-switch pulses and measuring the laser intensity as a function of delay time and discharge conditions 377) Similar experiments were performed by Lee era/.378). 

Detonation Transients and Unstable Detonation Processes. Allen et al (Ref 1) made detonation velocity vs chge length. measurements on RDX (—65+100 mesh), fine grained TNT (—35 —150) coarse, low-density TNT (—8+10) 50/50 fine-coarse TNT, cast TNT, low-density. mixts of 80/20 TNT/AN, and mixts of 90/10 AN/RDX. Deton velocities were measured by a rotating mirror streak camera and by the pin oscillograph technique, in most cases simultaneously Their exptl data showed six different types of velocity transients ... 

Following table gives relation betw density and deton vel, detd by rotating mirror camera, for TNT phlegmatized RDX ... 

Streak record, rotating mirror, single rotor Streak record, rotating 2 x 10-9 10-8... 

This is due to the image re-writing propensity of the rotating mirror and many drum-camera systems. Small auxiliary detonating charges can be used in a number of ways to block off light and image exactly when required. 

Jacobs (Ref 4), with a rotating mirror camera, measured a detonation velocity of 5200 m/s with a 1 diam cartridge, 5600 m/s with a 1 5/8 diam cartridge, and 8500 m/s with a 2% diam cartridge (d of 1.6 for pressed material)... 

Bergdolt (Ref 12) used the Mach-Zehnder interferometer and a short duration light source with a rotating mirror cameraito obtain interferograms of projectiles and the air flow patterns around them... 

A deton wave once formed in an expl has a tendency to die out or "fade if the diam of the expl is below a certain min (called boundary diam). It may be detd by using a cast cone detonated from the base. The diam of the cone at which the wave is extinguished is a measure of the fading properties of the expl. The observation may be made photographically by means of a rotating mirror camera. The value so obtd tends to be less than the value from cylindrical columns of expl. See Vol 4, p D223 Ref D.W. Woodheath R. Wilson, Nature 167, 565(1951)... 

Drehspiegelkamera (Rotating Mirror Camera) See under CAMERAS in Vol 2 of Encycl, p C14-L... 

Figure 10.10—Double beam spectrometer with a rotating mirror. Model 1R 435 (1986, reproduced by permission of Shimadzu).

Figure 11.14—Optical path between the monochromator exit and the detector for two double beam instruments (rotating mirror model and semi-transparent mirror model). Instruments with rotating mirrors are similar to those used in IR spectrophotometers. However, the light beam from the source goes through the monochromator before it hits the sample. This minimises photolytic reactions that could occur if the sample is exposed to the total radiation from the source. The optics of instruments with two detectors are simpler and only one mirror, semi-transparent and fixed, is necessary to replace the delicate mechanisms of synchronised, rotating mirrors.

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