Lens products are a common type of product in the field of optics, used to control the propagation and focusing of light. Here are some common lens products:

1. Convergent lens (convex lens): Convergent lens has a convex shape that can converge light rays to a focal point. Common applications include telescopes, microscopes, projectors, photographic lenses, etc.

2. Defocus lens (concave lens): Defocus lenses have a concave shape that can scatter light and cause it to diverge. Common applications include myopia correction glasses, microscopes, laser equipment, etc.

3. Double convex lens: A double convex lens is an optical device composed of two convex lenses. It can focus light onto a focal point and produce an amplification effect. Common applications include camera lenses, magnifying glasses, etc.

4. Double concave lens: A double concave lens is an optical device composed of two concave lenses. Similar to biconvex lenses, biconvex lenses can correct spherical distortion and are widely used in fields such as myopia glasses and microscopes.

5. Progressive lens: The curvature radius and diopter of a progressive lens gradually change, which can correct certain visual problems, such as astigmatism. Common applications include eyeglass lenses, visual aids, etc.

These lens products are not only widely used in optical instruments and equipment, but also widely used in fields such as glasses, photography, medical treatment, and scientific research. The shape, materials, and parameters of lens products may vary depending on specific requirements and application scope.