# Reduction of Uneven Brightness and Ghosts of Aerial Images Using a Prism in a Micromirror Array Plate

## TL;DR

This paper introduces a method using a prism to reduce ghost images and uneven brightness in aerial displays.

## Contribution

A novel method using a prism to suppress both ghosts and luminance unevenness in aerial images.

## Key findings

- The proposed method suppresses luminance unevenness better than conventional ghost removal methods.
- The method reduces ghost formation more effectively than a micromirror array plate alone.

## Abstract

A micro-mirror array plate is a type of aerial image display that allows an observer to touch the aerial image directly. The problem with this optical element is that it produces stray light, called a ghost, which reduces the visibility of the aerial image. Conventional methods can suppress the occurrence of ghosts; however, depending on the observation position, uneven luminance is produced in aerial images. Therefore, in this study, we proposed a method for eliminating ghosts while suppressing the unevenness in the luminance of an aerial image using a prism. In the proposed device, a prism is placed between the liquid crystal display and the diffuser, which is the light source of the aerial display. The experimental results showed that the proposed method can suppress the unevenness in the luminance of aerial images better than the conventional ghost removal methods and can reduce the formation of ghosts better than the micromirror array plate alone. Therefore, the proposed method can be shown to be a ghost removal method that can suppress unevenness in the brightness of aerial images.