I am looking for such lenses as well.
In general putting the aperture at the front or outside is avoided because not good; best is to put the aperture more or less in the center of the objective. With the aperture in front you'll have more aberrations and/or need bigger and more expensive design.
Only in two cases the front aperture design is used:
- if the lens is very small and simple, like, really just one group (see the Kodak vest camera and the Triplet), here you cannot put the aperture in the middle! Choose, in the front or in the back.
- Otherwise, you put the aperture in front only if you are absolutely forced to do that, typically for coupling with other optical systems.
Small & simple:
The Wollaston meniscus is the oldest/simplest photographic lens, just one lens. It is the best single-lens performer for wide angle. Aperture is in the front; the Kodak vest is a version of it.
Mobile phone lenses; to make them so compact, the aperture is usually placed at the brim of the front lens. Not really outside, but on the brim.
Pinholes and many probe objectives, that need to peep from an hole; the hole is the natural aperture and the lens must be built to use all the light that goes through such hole; putting another aperture will cause vignetting. Nice example the SO spy lenses by Zeiss Jena:
Marco Cavina or see the catalog of Marshall Electronics.
- Laser scanning lenses, called F-theta Rogonar; the laser light is coming form the aperture position.
- All eyepieces: the aperture is well outside, at the "exit pupil", so I can place my eye with my iris in this place.
If you are curious about aberrations etc, the best short introduction I've found are those slides from Jena:
Gross Jena 2017; lecture 11/3, stop position.
I discovered that the one of first photographic lens ever, the Wollaston meniscus, has front aperture! The Kodak pocket vest is an achromatic version of this lens. The aperture optimal position is really there, few mm in front of the lens.