 By Manneville P.

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Physics and Chemistry Basis of Biotechnology

On the finish of the twentieth century, a major growth used to be made in biotechnology in its widest feel. This growth was once principally attainable because of joint efforts of most sensible educational researchers in either natural primary sciences and utilized examine. the excess worth of such interdisciplinary ways used to be essentially highlighted throughout the ninth eu Congress on Biotechnology that was once held in Brussels, Belgium (11-15 July, 1999).

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P and Q are conjugate points. Axial distances z1 , z2 are measured from the focal planes F1, F2 shows that the principal planes are conjugate planes of unit magnification: if the object point is in one, the image point is in the other and at the same height. By substituting z1 ¼ 0, we obtain z2 ¼ 1, infinite magnification, and each focal plane has a conjugate plane at infinity. The constants f1 and f2 are the principal focal lengths of the system. 9). 9). 20) respectively for a thin lens, a single refractive surface and a spherical mirror.

10) for v : v ¼ fu=ðf þ uÞ ¼ 0:05ðÀ0:7Þ=ð0:05 À 0:7Þ ¼ 0:054 m ¼ 54 mm. We have already related the focal length of the lens to the refractive index n and the radius of curvature r of the two equally curved surfaces. 4) gives the focal length   1 1 1 ¼ ðn À 1Þ À f r1 r2 ð2:11Þ where the subscripts refer to the first and second interfaces crossed by the incident light. 3(a), r1 > 0 and r2 < 0; hence both surfaces add to the positive value of the power. 3(b), the signs of r1 ; r2 are the opposite, and both contribute to a negative power.

3 Or, more rarely, a maximum. 3 Convex (a) and concave (b) lenses changing the curvature of a wavefront. 8), the curvatures are evaluated on wavefronts immediately adjacent to the lens We now introduce the term vergence for the curvature of a wavefront, using a definition which applies generally to refraction and reflection at curved surfaces. The vergence V of a wavefront emanating from (or converging to) an object (or image point) at signed distance L in a medium with refractive index n is defined as V ¼ n=L; the sign of L is chosen so that vergence is positive for a converging wavefront and negative for a diverging wavefront.