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Re: [Phys-l] pinhole camera



The final step, before packaging and sterilization, in the manufacturer of IOLs (intra-ocular lenses), was to verify their focal lengths. This was done using a vertical bench consisting of a light source and collimator, an air force resolution target, a platform for the tested lens and a travelling microscope w/ a dial indicator. The indicator was set so zero was the front (image side) surface of the lens. The machinist and the QC person called the image on which the microscope focussed an "aerial image".
bc, assisted in its design and wrote the majority of the company's GMPs (good manufacturing practices required by the FDA), among much else.

Robert Cohen wrote:

I believe Jeff adequately addressed Herb's question (how can you be sure
that the image is there when you remove the screen?). I'd like to add
that the image can more easily be observed if you place a wire hoop at
the location of the image (with the image contained within it). That
way, the eye has something to focus on.

EYE . . . . Hoop (with image) . . . . Lens . . . . Object

This works best for real images. Virtual images can also be seen this
way but the wire hoop must be larger than the lens, so that the observer
sees the hoop "outside" the lens and sees the image "inside" the lens.

----------------------------------------------------------
Robert A. Cohen, Department of Physics, East Stroudsburg University 570.422.3428 rcohen@po-box.esu.edu http://www.esu.edu/~bbq

-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Jeffrey Schnick
Sent: Friday, April 13, 2007 8:08 PM
To: Forum for Physics Educators
Subject: Re: [Phys-l] pinhole camera

We have, in the physics lab, this big converging lens, about 40 cm in diameter, with about a 45 cm focal length. An incandescent light bulb is placed about 6m in front of the lens, on the principal axis of the lens. As part of a laboratory exercise, a student positions herself about 90 cm behind the lens such that the lens is at eye level. The student's lab partner positions a piece of plain white copier paper between the student and the lens, at the location of

cut