Idea to refracting light
Light go throught water to focus

Water lens research

Water lens, "triplet" for refractor telescope.

October 2019 - manufacturing process of glass lens

Over mould is transparent round flat glass (thickness 4 - 15 mm) heated on 450 to 730°C.

By air pumping system, glass slump to the required dept, then glass cool down.

Surface of glass does not touch to mould through the entire process, so the surface of glass have no inequality, roughness of mould.

Then slumped glass can be built-in to water lens with 3 surfaces - glass water glass.

March 2019       11,3 magnitude was reach

Water lens, diameter 300mm, focal length 1000mm, 15 seconds exposure, ISO 12800, Canon 750D Photocamera took stars region 47 Boo, 44 Boo, HIP 74340 (22 th March 19h32m)

Februar 2019

Optical surfaces can by made by precision slumping glass method.

Keywords: precision Glass Slumping, fusing glass, slump glass, Precision glass moulding, lightweight optics

The Astronomical Observatory of Brera (INAF-OAB) is investigating a novel slumping technique for the manufacturing of stiff and lightweight optical segments.

Januar 2019

was test water lens from glass and plexiglass with diameter 180mm, focal length 550mm

Mizar and Alcor, video by smartphone in hands behind eyepiece 10mm, 22 th Januar 2019, 6:12 PM


Moon through water lens, single shot by Samsung J6 mobile, 16 th Januar 2019, 5:02 PM


August 2018

was test water lens from glass and plexiglass with diameter 180mm, focal length 550mm

first light - jupiter throught water lens, single shot by sony xperia mobile

Spring 2018
was tested by thermo slumping and annealing more like 16 pieces of plexiglass with diameters 300mm.


Januar 2018

water lens (water between two Punktuell 1.5, glass mineral / index 1.525, SPH - 2)

water lens with eyepiece

object behind eyepiece, photo by sony xperia mobile phone

Spring 2017

A first prototype of a 74cm (740mm) diameter water lens was built, focal length is
85 cm. Two plexiglass covers were used with round roof windows skylight with sagitta
12 cm, diameter 74 cm and 5 mm thickness of plexiglass. Borders bound together
sealing with rubber band and screwed with screws. Through a 2cm hole in the seal, water was poured inside.

From May 2017 was start research and development with experimenting with water lenses. Experiments take circa 2000 individual single shot photos and more videos in 20 GB (gigabyte)

Motivation is research and how to build low cost and big diameter Water lens.

Water lens is an optical element that has water inside the body. The lens consist of two transparent materials, plexiglass or glass coils with various convex shape, along the edges joined by two circular frames with rubber seal and screwed or glued. Through the hole in the rubber seal, water is poured inside with the required refractive index. After the water has been fully filled, the water lens is ready. Water is a transparent substance that, like glass, transmits light and breaks the light rays into focus, so that the lens - the optical element can be use into the refractor optical telescope.

Water lens can be triplet with three surfaces - glass, water, glass.

In big glass lens (refractors) is problem with lens sag. Water is 2,5 times easier like glass, so lens sag will be smaller, Water lens with diameters above 100cm, 150cm and bigger will have smaller lens sag, like glass lens.

Nearest plan is to build and test:

  1. water lens (triplet) with circa 300mm diameter, focal length from 1000 to 2000mm
  2. water lens (triplet) with circa 500mm diameter, focal length from 1000 to 3000mm
  3. water lens (triplet) with circa 1500mm diameter, focal length from 3000 to 6000mm

My name is Richard Lunter.

If you like this website and you can donate research please donate by paypal

Research go on.

                                                                              Contact form