An optical layer stack, comprising: a first layer; a second layer; a first spacer part associated with the first layer; and a second spacer part associated with the second layer, wherein the two spacer parts (106; 108) comprise groove and tongue (110; 112) for an engagement in a stacking direction of the optical layer stack and for a shiftability of the first spacer part with respect to the second spacer part in the lateral direction and in the stacking direction the tongue has a smaller width than the groove, wherein the first and the second spacer part (106; 108) are connected to each other by means of an adhesive between groove and tongue in order to provide a connection between the first and the second spacer part (106; 108) and a spacing of the first and second layer (102; 104) in stacking direction; characterized in that the first layer carries or forms imaging optics and a coefficient of thermal expansion of the adhesive and a shape of a groove and the tongue are selected so that, across a temperature range from -40° to 80°C, a distance of an image plane of the imaging optics in the direction of an optical axis of the imaging optics to the second layer deviates by less than ± 1% of an objective focal length of the imaging optics at 20°C from a position of the image plane at 20°C, or the first layer carries or forms a first imaging optics and the second layer a second imaging optics and a coefficient of thermal expansion of the adhesive and a shape of the groove and the tongue are selected so that, across a temperature range from -40° to 80°C, a distance of an image plane of the first imaging optics in the direction of a common optical axis of the first and second imaging optics towards an object plane of the second imaging optics deviates from zero by less than ± 1% of the greater one of the objective focal lengths of the first and second imaging optics at 20°C, wherein the groove comprises a wall facing the optically used area and a wall facing away from the optically used area, and wherein the spacing of the first and second layer (102; 104) by the adhesive in the stacking direction is so that the walls of the groove are still spaced apart from the spacer part comprising the tongue, and. wherein the spacing of the first and the second layer (102; 104) by the adhesive in the stacking direction is so that the tongue is spaced apart from a bottom of the groove by a length L unequal to zero and the adhesive is contained in the groove from the bottom beyond the length L. a first layer; a second layer; a first spacer part associated with the first layer; and a second spacer part associated with the second layer, wherein the two spacer parts (106; 108) comprise groove and tongue (110; 112) for an engagement in a stacking direction of the optical layer stack and for a shiftability of the first spacer part with respect to the second spacer part in the lateral direction and in the stacking direction the tongue has a smaller width than the groove, wherein the first and the second spacer part (106; 108) are connected to each other by means of an adhesive between groove and tongue in order to provide a connection between the first and the second spacer part (106; 108) and a spacing of the first and second layer (102; 104) in stacking direction; characterized in that the first layer carries or forms imaging optics and a coefficient of thermal expansion of the adhesive and a shape of a groove and the tongue are selected so that, across a temperature range from -40° to 80°C, a distance of an image plane of the imaging optics in the direction of an optical axis of the imaging optics to the second layer deviates by less than ± 1% of an objective focal length of the imaging optics at 20°C from a position of the image plane at 20°C, or the first layer carries or forms a first imaging optics and the second layer a second imaging optics and a coefficient of thermal expansion of the adhesive and a shape of the groove and the tongue are selected so that, across a temperature range from -40° to 80°C, a distance of an image plane of the first imaging optics in the direction of a common optical axis of the first and second imaging optics towards an object plane of the second imaging optics deviates from zero by less than ± 1% of the greater one of the objective focal lengths of the first and second imaging optics at 20°C, wherein the groove comprises a wall facing the optically used area and a wall facing away from the optically used area, and wherein the spacing of the first and second layer (102; 104) by the adhesive in the stacking direction is so that the walls of the groove are still spaced apart from the spacer part comprising the tongue, and. wherein the spacing of the first and the second layer (102; 104) by the adhesive in the stacking direction is so that the tongue is spaced apart from a bottom of the groove by a length L unequal to zero and the adhesive is contained in the groove from the bottom beyond the length L.