The stakes have risen even higher in this third book in the Hourglass series. The Hourglass is a secret organization focused on the study of manipulating time, and its members -- many of them teenagers -­have uncanny abilities to make time work for them in mysterious ways. Inherent in these powers is a responsibility to take great care, because altering one small moment can have devastating consequences for the past, present, and future. But some time trav­elers are not exactly honorable, and sometimes unsavory deals must be struck to maintain order. With the Infinityglass (central to understanding and harnessing the time gene) at large, the hunt is on to find it before someone else does. But the Hourglass has an advantage. Lily, who has the ability to locate anything lost, has determined that the Infinityglass isn't an object. It's a person. And the Hourglass must find him or her first. But where do you start searching for the very key to time when every second could be the last?

Kaleb Ballard was never supposed to be able to see ripples—cracks in time. Are Kaleb’s powers expanding, or is something very wrong? Before Kaleb can find out, Jonathan Landers, the man who tried to murder his father, reappears. Why is he back, and what, or whom, does he want? In the wake of Landers’s return, the Hourglass organization is offered an ultimatum by a mysterious man. Either they find Landers and the research he has stolen on people who might carry the time gene, or time will be altered—with devastating results for the people Kaleb loves most. Now Kaleb, Emerson, Michael, and the other Hourglass recruits have no choice but to use their extraordinary powers to find Landers. But where do they even start? And when? Even if they succeed, just finding him may not be enough. . . . The follow-up to Hourglass, Timepiece blends the paranormal, science-fiction, mystery, and suspense genres into a nonstop thrill ride where every second counts.

A Course in Lens Design is an instruction in the design of image-forming optical systems. It teaches how a satisfactory design can be obtained in a straightforward way. Theory is limited to a minimum, and used to support the practical design work. The book introduces geometrical optics, optical instruments and aberrations. It gives a description of the process of lens design and of the strategies used in this process. Half of its content is devoted to the design of sixteen types of lenses, described in detail from beginning to end. This book is different from most other books on lens design because it stresses the importance of the initial phases of the design process: (paraxial) lay-out and (thin-lens) pre-design. The argument for this change of accent is that in these phases much information can be obtained about the properties of the lens to be designed. This information can be used in later phases of the design. This makes A Course in Lens Design a useful self-study book and a suitable basis for an introductory course in lens design. The mathematics mainly used is college algebra, in a few sections calculus is applied. The book could be used by students of engineering and technical physics and by engineers and scientists.

It’s mid-summer’s day and thirteen-year-old Elle and her Leapling classmates are visiting the Museum of the Past, the Present and the Future. But on the day of the school trip, disaster strikes, and the most unique and valuable piece in the museum, the Infinity-Glass, is stolen! And worse still, Elle’s friend and fellow Infinite, MC2 is arrested for the crime! To prove his innocence Elle must leap back centuries in time, to a London very different from today. Along the way she will meet new friends, face dangers unlike any she has ever known, and face an old enemy who is determined to destroy her. Can Elle find the missing Infinity-Glass and return it to its rightful home before it’s too late?

This is the first volume of a monumental work that will provide a complete treatment of all theoretical aspects of reflecting telescope optics. It addresses all specialists in the field, both within the astronomical community and in industry, and, consequently, particular emphasis is placed on subjects such as practical alignment, test techniques, and maintenance aspects. Whereas the second volume will concentrate on technical aspects and modern developments, this one is devoted to the theory of reflecting telescope optics and, together with the historical development, it will also prove to be useful to students. This book has real classic potential.

Laser Beam Shaping: Theory and Techniques addresses the theory and practice of every important technique for lossless beam shaping. Complete with experimental results as well as guidance on when beam shaping is practical and when each technique is appropriate, the Second Edition is updated to reflect significant developments in the field. This authoritative text: Features new chapters on axicon light ring generation systems, laser-beam-splitting (fan-out) gratings, vortex beams, and microlens diffusers Describes the latest advances in beam profile measurement technology and laser beam shaping using diffractive diffusers Contains new material on wavelength dependence, channel integrators, geometrical optics, and optical software Laser Beam Shaping: Theory and Techniques, Second Edition not only provides a working understanding of the fundamentals, but also offers insight into the potential application of laser-beam-profile shaping in laser system design.