Alexei Kostroma, YELLOW EARTH 23:49 (Memory of the sun-2), 2015, Organic yellow lemon pigment and invisible nano colour on canvas, black acrylic frame, 30 x 25 cm, Photo: Archive, Alexei Kostroma, YELLOW EARTH 22:17 (SUN), 2016, Organic yellow lemon pigment on canvas, 100 x 100 cm, Photo: Archive, Alexei Kostroma, YELLOW EARTH 17:34, 2016, Organic yellow lemon pigment on canvas, 60 x 50 cm, Photo: Archive, Alexei Kostroma, NANO 547, 2014, Invisible nano colour on eggshells, laser cut on canvas, 100 x 100 x 7 cm, Photo: Archive, Adolf Luther, Struktur für Licht, 1962, Eggshells, gesso, oil and pigment on wood, 54 x 54 x 10 cm, setform.de, Adolf Luther, 'Zwei Brennpunkte', 1968, 2 layers of 16 square concave mirrors (in 2 sizes: 17 x 17 cm on 35 x 35 cm) mounted on a black wooden plate, with acrylic glass hood, 150 x 150 x 11 cm, Photo: setform.de, Adolf Luther, Stehlinsen (Detail), 1977-78, Concave mirror, semitransparent, synthetic framework, steel pole with foot, ∅ 60 cm, height ca. 240 cm, Photo: Archive, Adolf Luther, Hohlspiegelobjekt (silver blue), 1976, mixed media, 61 x 50 cm, , Adolf Luther, Adolf Luther, 1968, mixed media, 45 x 45 cm, , Adolf Luther, Struktur für Licht (Structure for light), 1962, Eggshells, gesso, oil and pigment on wood, 54 x 54 x 10 cm, Photo: Archive,