Why the hell would you use a dpss ? Why not a single mode 638nm to make a 4 foot wide circle on grass ? Of course any product has to be safe for the general public so there's also that.
Exactly.
Lets see, a 16.64W or 16,640mW 532 DPSS lab laser would be an aprox. $28,000 532nm DPSS with adjustable power supply -- not exactly a pointer and absurdly dangerous if it even could meet his other requirements. see:
https://www.ultralasers.com/proinfo.php?productid=837&cat=3&page=1&featured A little over the 5mW or less FDA legal limitation lol
It helps to know something about what you are wanting to make, imagining can be made. Even if possible, importantly, you need to know the legal considerations, and safety considerations and so on. That you are asking a hobbyist laser forum means you don't have a clue or any experience based knowledge in the field of lasers
It's most likely not patentable --putting a laser pointer in a box or tube with a window probably does not qualify as a patentable anything. so...
"Under US Law, you cannot patent an idea." and "You cannot patent an idea for an invention. The invention itself has to be produced or a patent application containing the invention must be filed with the U.S. Patent and Trademark Office (USPTO). While all inventions start with an idea, not every idea can be called an invention." see:
https://www.legalzoom.com/articles/can-you-patent-an-idea
It is just an imagining/idea from what you say.
Either way, your imagined device would never be allowed to be legally sold/fly as a product in USA under US FDA laser laws, rules and regulations as a product with an output over 5mW due to safety considerations.
FDA Laws, rules and regulations limit any product to 5 mW or less as follows:
"Laser products promoted for pointing and demonstration purposes are limited to hazard Class IIIa by FDA regulation.
21 CFR 1040.11(b) and 1040.11(c), limit surveying, leveling, and alignment, and demonstration laser products to Class IIIa. This means that pointers are limited to 5 milliwatts output power in the visible wavelength range from 400 to 710 nanometers.. Pointers may not exceed the accessible emission limits of CDRH Class IIIa or IEC Class 3R."
see:
https://www.fda.gov/radiation-emitt...rtant-information-laser-pointer-manufacturers
Even light show laser projectors that could make a circle are limited to 5mW or less ... see:
https://www.fda.gov/radiation-emitt...-and-entertainment-products/laser-light-shows
US FDA Laws, Rules, and Regulations do not allow "laser show" projectors over 5mW to be legally used for "laser shows" without a "Variance" to deviate from the Regulations. Variance approval for any particular laser show to be run specifically requires all details of both the proposed equipment and the proposed use. You can see what is involved here:
http://www.laserist.org/us-regs.htm You would not be given a "variance" if there is/was any chance of anyone being put in harms way/directly exposed to a laser in use.