So long as you consider 808 nm for purposes of choosing lens material and associated refractive index and other properties, you are okay treating the system as though it is in the visible range.

For the purpose of designing optical systems optics is optics at all wavelengths. Mostly it’s just a question of what materials are transparent / reflective at the wavelength of interest. 808 nm is very close to visible and practically all materials used for optics in the visible are perfectly good materials at 808. You will have to account for the slight change in index due to dispersion. If you are buying off the shelf components you might want to verify that any dielectric coatings perform well at 808.

So the rules never change, but at extreme wavelength the game changes. For example it is hard to find transparent materials below 200 nm, and even metallic mirrors absorb extreme UV. At the other end of the spectrum transparent materials are available to 12 um or so.

However another game changer in the infrared is that everything including the optics themselves are glowing. The curve for black body radiation of an object at 300K is peaked around 9 um. This doesn’t change the rules of lens design, but it does affect system design. However there is very little thermal radiation below 4 or 5 um,

So, basically, from 200 nm to 4um it’s all just optics.

I dont know why you could not use visible range optics. The problem may be finding the correct material lenses for doing this. Make sure the transparency of the lenses is in the range that you want. Make sure to use Gaussian optics equations since you are working with a laser.