投影描绘器（英语：Camera lucida），又称明箱或亮箱，是一种用于艺术家作画时作帮助用的光学仪器。

威廉·海德·沃勒斯顿（William Hyde Wollaston）在1806年申请了它的专利。似乎有证据表明投影描绘器不过是重新发明了200年前开普勒在他的著作《折射光学》（Dioptrice，1611年）中清楚地描述过的设备。但到了19世纪，开普勒的描述完全被遗忘了，所以没有人质疑沃勒斯顿的声明。该术语「camera lucida」（投影描绘仪）是沃勒斯顿发明的。

A camera lucida is an optical device used as a drawing aid by artists.

The camera lucida performs an optical superimposition of the subject being viewed upon the surface upon which the artist is drawing. The artist sees both scene and drawing surface simultaneously, as in a photographic double exposure. This allows the artist to duplicate key points of the scene on the drawing surface, thus aiding in the accurate rendering of perspective.