About the wording “invisible light”, I note first that the writer of a patent application can be his/her own lexicographer – you can define a word any way you want, even in contrary to standard definitions, just as long as you say what you mean in the text of the application.

Please look at the actual text of this patent (which you can see if you go into PAIR – Patent Application Info Retrieval System - http://portal.uspto.gov/external/portal/pair – and typing in the number, 5,443,036).

What does the patentee mean by “invisible”?  The patent itself tells us: “The light pattern projected by the laser cat exerciser is invisible until intersection with an opaque surface. Lasers emitting various colors of coherent light can be used and the laser apparatus can be distinctively shaped and colored for easy identification.”  A claim also states that the “beam remains invisible between said laser and said opaque surface until impinging on said opaque surface”.  So the laser is invisible until it hits the wall. 

Please don’t make fun of the wording of a patent’s claims until you actually read the text of the Specification, which may define some of the offending wording.

Regarding the issue of whether or not this invention was novel, the USPTO will do a search of any written documentation it can find, and then consider whether the invention is novel (new) and non-obvious in light of the written documentation.  If people did this earlier, but it was never documented and that documentation published in an accessible way, then the USPTO has nothing to go on.

That said, if this were ever litigated (e.g., in a patent infringement lawsuit), the defendant could invalidate the patent if he/she supplied written documentation that this was done earlier. Thus, there is a check in the system.

Also of note, this patent application was filed in 1993, and the USPTO is today better at finding prior art than ever before (esp. with the ever-expanding internet). 

Given that, I’m going to assume that it’s mostly a situation where the inbox is filling ever higher, you aren’t going to get a medal for most careful scrutiny of a patent application, and far fewer applicants dispute an application you grant than an application you deny. Whether or not that qualifies as ‘laziness’ really depends on how fast the supply of applications vs. the supply of patent examiners forces the examiners to do a somewhat tepid job. Slackers and sweatshop workers both produce lousy product because they don’t put time into their work; but they aren’t exactly equally lazy…

I have, however, observed ferrets stealing things from the distracted humans trying to taunt another ferret with a laser pointer.

Patents do need to meet certain conceptual requirements of being “novel”, but I fear that, like many parts of a bureaucracy, the actual original requirements often get left aside and it turns more into a game of who can submit the paperwork properly, and who can write in a “patenty” way. You could submit poor paperwork for a cold fusion reactor and it would be denied, but submit something for amusing a cat with a laser pointer with all your t’s crossed and i’s dotted, in perfect “patent-ese” and in it goes.

“…directing a beam of invisible light produced by a hand-held laser…”

I’ve tried the invisible light trick and my cat just won’t fall for it.

At least in the UK something has to be ‘novel’ to get patented, i.e. not pre-existing, and it has to require some kind of specialist knowledge (i.e. if that guy in the street could think of it too, then it shouldn’t be patented).  It also has to be outside of public knowledge, i.e. if you tell a friendly reporter about your invention and they print it, no patents for you.

The fact that you can patent something that people already do and know about or own in the US is completely nonsensical.