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LENSES AND MIRRORS 99
Mirror Collector Converger, page [32 y
What office does the mirror collector serve? /^L+^^ Describe the effect of spherical aberration in such inirn :
134. Do all such mirrors have this fault? <J/H?*?'
135. May spherical aberration in such minor be eon\rted?^7£o7^
136. What constitutes the parabolic or the eliptical mirror: . -><u — 137. What is the practical effect of spherical aberration? W*<
138. Is spherical aberration detrimental to good projection? , 139. Will a properly installed mirror converger collect more light than the 4*/2 inch diameter plano-convex condenser?
140. Examine Figs. 45 and 46 and explain the points raised in the text covering them. ^»**-u
141. Is the mirror a more efficient collector of light than the plano-convex condenser ?
142. Name one reason why the reflector type arc produces a hotter spot than an arc with which a plano-convex condenser
is used. ^6-^-* < . y\JLs±,<: K,l<iT\
143. Name one advanatge of locating the rotating shutter between the light source and the aperture source.
144. Is the mirror an efficient light collector as compared with the glass condenser?
145. Explain the real cause of spherical aberration in a spherical mirror working with a projector light source. ' '*-££^
146. How may spherical aberration be corrected?
147. Explain the reduction or enlargement of the spot diameter caused by advancing or retarding the light source from_the mirror.
148. What two surfaces present the highest possible accuracy and efficiency in light reflection ? .
149. What is placed on the back of the mirror?
150. What backing is applied on top of the silver?-*^
151. Is it essential to locate the light source at a certain fixed distance in the mirror surface, and the mirror a fixed distance from the aperture?
152. What is the distance from the light source to the mirror vertex called?
153. What term is applied to the distance from the mirror vertex to the aperture ?
154. Must mirror focus and mirror working distances be maintained exactly ?
155. Are these distances different for mirrors of different focal lengths? i ■ t
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