| 摘要 |
PURPOSE:To accurately measure MTF, by constituting the title apparatus so that a reference radiation black body and the lattice-like body adjacent thereto are arranged to an optical system on the body surface side thereof and the lattice-like body can freely alter the space frequency of the part faced to the reference back body and has a reference opening at every frequency. CONSTITUTION:A chart 4 is constituted so that lattice groups each having a reference opening 10 at the center thereof and stepwise changing in space frequency are continuously provided to an elongated piece 6. The elongated piece 6 is rolled in a cassette 7 and taken up from one end to the other end thereof to stepwise change space frequency. The charts 4 thus constituted are arranged so as to be adjacent to the surface of a reference radiation black body 3 and, for example, by rotating each chart in the quantity corresponding to the length L of one chart by a stepping motor to stop the same, space frequency is altered. By continuously obtained an output signal from the infrared ray detector arranged on an image surface side while the space frequency of the chart 4 is changed, MTF of a lens to be inspected can be measured. |
