Optical device

An image forming apparatus, comprising:

• a photoconductive drum;
• a supply of toner;
• and
• an optical device, comprising:
• a lens mirror array opposed to a light emitting section extending in a first direction, the lens mirror array including a plurality of optical elements side by side in the first direction, the plurality of optical elements respectively including incident-side lens surfaces on which light emitted from the light emitting section is made incident, emission-side lens surfaces that emit the incident light, and reflection surfaces that reflect the light made incident from the incident-side lens surfaces toward the emission-side lens surfaces, a cross section orthogonal to the first direction of the lens mirror array having a constricted shape, a center of which is narrower than both ends thereof that are along an optical path on which the light emitted from the light emitting section passes;
• and
• a holder including a slit having a width smaller than a width of both ends in the cross section of the lens mirror array and larger than a width of a center in the cross section and extending in the first direction, the holder holding the lens mirror array in a state in which a constricted portion in the center in the cross section of the lens mirror array is disposed in the slit.