Hooke used a bi-convex objective lens placed in the snout and two additional lenses, an eyepiece lens and a tube or?field?lens. When combined, the lenses suffered from significant chromatic and spherical aberration and yielded very poor images. Hooke attempted to correct the aberrations by placing a small diaphragm into the optical pathway to reduce peripheral light rays and sharpen the image. Unfortunately, this resulted in very dark samples containing a significant degree of diffraction artefacts that, when combined with spherical and chromatic aberrations, seriously degraded the image quality. To combat dark specimen images, Hooke designed an ingenious method of concentrating light on his specimens, as shown in the illustration. He passed light generated from an oil lamp through a water-filled glass flask to diffuse the light and provide a more even and intense illumination for the samples. Even with all the intricate details involved with this microscope, it still fell short in optical performance when compared to the simple Leeuwenhoek microscope.