Thursday, December 29, 2011

Entry #3: The case for a rapidly tunable lens

Autofocusing technology has existed for a number of decades, dating back to 1970's with the Konica C35 AF and later became a popular feature of consumer video cameras. Now autofocusing lens assembles can be had in very inexpensive webcams available today.  However, almost every readily available autofocusing camera features mechanically driven assemblies to move lenses with gears, a method inherently slow. Even more, current autofocusing lens assemblies can only provide a picture that is relative to the rest of the optical assembly.

Image flaws become exceptionally problematic in telescopes. Refractive telescopic optical assemblies come in three common forms:

Singlet Lens
  • includes a single double convex (DCX) lens
  • able to bring a single narrow band of the color spectrum to focus at a single time
  • often used in magnifying glasses
Courtesy Wikimedia Commons
Achromatic Doublet Lens
  • includes a double convex (DCX) lens, known as the crown and often a positive meniscus (PMns) or a plano concave (PCV) lens, known as the flint and is made of a different type of glass
  • able to bring two medium color bands to focus at a time, most often red and blue, leaving green at a nearer focus
  • most common form of beginning amateur level refractive telescope
Courtesy Wikimedia Commons
Apochromatic Lens
  • comes in a doublet form similar in layout to an achromat but made with a higher quality glass for low color dispersion, and also comes in triplet form featuring a double convex (DCX), double concave (DCV) and plano convex (PCX) lenses, each made of varying forms of glass with low color dispersion properties
  • able to bring most of the visible color spectrum to focus at once
  • found in most high-dollar refractive telescopes
Courtesy Wikimedia Commons
Chromatic aberration in an image produced by a telescope, can be devastating for clarity.  However, the rapidity of an electrically driven liquid lens, allows for such a dramatic increase in focusing rate that one could oscillate the focus of a lens at a comparable change rate observable on most LCD computer displays, making the oscillations imperceptible to the human eye .  This would provide a view through a telescope that was in perfect focus at every wavelength and every depth within a given field as the lens rapidly oscillated the focus. As a second and possibly a primary benefit, atmospheric distortion could potentially be minimized through this system as well, greatly limiting the "boiling-effect" one can see when observing an object such as the Moon.

I hypothesize that a rapidly oscillating liquid lens will allow comparable seeing through even a simple singlet lens to that of an apochromatic assembly by the means described above. Later today, I will update this post with an illustration example for the described system.

An illustration of the bending optical path with an oscillating tunable lens.  Click image to animate.

Wednesday, December 28, 2011

Entry #2: In pursuit of an affordable liquid lens

Liquid lenses have been around for at least the past decade and the theory behind their operation extends back decades before.  However, obtaining a lens assembly is rather difficult.  Currently, there are several manufacturers that are distributing units: Varioptic's Arctic [2] [3] [4], Optotune Tunable Lenses [2] [3],and recently poLight's TLens [2].  Both Varioptic and poLight prefer to distribute to large corporations rather than individual consumers unfortunately.  However, Digitus offers a webcam that features Varioptic's Arctic lens and for a very reasonable price.  It has been "out-of-stock" for the past several month though and they never responded to my inquiry as to when more would be available.  This leaves Optotune's electrically tunable and manual tunable lens but at a vicious several hundred dollars per lens; far outside a likelihood of marketability.

For now, I'll leave you with the future idea of a rapidly focusing lens.  The Dynamorph Lens comes from  the Ishikawa lab in Tokyo (not for sale...)

EDIT: I've learned Philips also has a liquid lens they debuted in 2004 called FluidFocus [2] [3]. However, I've found no applications of the technology beyond showing the units at technology fairs. Below is a video demonstrating their lens.


Tuesday, December 27, 2011

Entry #1: Current Project List

As a person with a lot of ideas that come and go at a whim, I'd like to begin sharing some of them in the hopes that I will inspire someone else to innovate.  I will note that for any specific design plans that I post in the future (there will be many) I will gladly allow you to use them as you please so long as you offer credit where credit is due and I will do the same.  As for intellectual property rights, patents, etc. I strongly disagree with them and feel they stand in the way for future innovation.

Current Project List
  1. Digitus controlled autofocusing monoviewer
  2. Digitus rapid tuning lens
  3. Edmund Optics rapid tuning lens
  4. Segmented mirror demonstration
  5. Spherical mirror binocular
  6. Heated window shade de-icer
  7. Wind tunnel