A sensor apparatus includes a photosensitive sensor, a cover, and a moving mechanism. The photosensitive sensor includes a first lens and a second lens which focus on a photosensitive element. The cover includes a first slit arranged on an optical axis of the first lens and a second slit arranged on an optical axis of the second lens. The moving mechanism is configured to move the photosensitive sensor and the cover relative to each other so that the second slit is arranged on the optical axis of the first lens.

A self-referenced ambient radiation thermometer determines a temperature of a blackbody object and includes a temperature stabilized detector; a detector lens; a Lyot stop; a collimating lens; a field stop; an optical chopper such that the central radiation received by the temperature stabilized detector is modulated at a modulation frequency of the optical chopper; an objective lens in optical communication with the blackbody object and the temperature stabilized detector, optically interposed between the blackbody object and the field stop and that: receives the central radiation from the blackbody object and communicates the central radiation to the field stop; and a temperature-stabilized isothermal enclosure that provides a stable temperature and isothermal environment to elements disposed in the temperature-stabilized isothermal enclosure, wherein the elements disposed in the temperature-stabilized isothermal enclosure comprise: the temperature stabilized detector, the detector lens, the collimating lens, the Lyot stop, and the field stop.

A sensor apparatus includes a photosensitive sensor, a cover, and a moving mechanism. The photosensitive sensor includes a first lens and a second lens which focus on a photosensitive element. The cover includes a first slit arranged on an optical axis of the first lens and a second slit arranged on an optical axis of the second lens. The moving mechanism is configured to move the photosensitive sensor and the cover relative to each other so that the second slit is arranged on the optical axis of the first lens.

A sensor apparatus includes a photosensitive sensor, a cover, and a moving mechanism. The photosensitive sensor includes a first lens and a second lens which focus on a photosensitive element. The cover includes a first slit arranged on an optical axis of the first lens and a second slit arranged on an optical axis of the second lens. The moving mechanism is configured to move the photosensitive sensor and the cover relative to each other so that the second slit is arranged on the optical axis of the first lens.

A self-referenced ambient radiation thermometer determines a temperature of a blackbody object and includes a temperature stabilized detector; a detector lens; a Lyot stop; a collimating lens; a field stop; an optical chopper such that the central radiation received by the temperature stabilized detector is modulated at a modulation frequency of the optical chopper; an objective lens in optical communication with the blackbody object and the temperature stabilized detector, optically interposed between the blackbody object and the field stop and that: receives the central radiation from the blackbody object and communicates the central radiation to the field stop; and a temperature-stabilized isothermal enclosure that provides a stable temperature and isothermal environment to elements disposed in the temperature-stabilized isothermal enclosure, wherein the elements disposed in the temperature-stabilized isothermal enclosure comprise: the temperature stabilized detector, the detector lens, the collimating lens, the Lyot stop, and the field stop.

A sensor apparatus includes a photosensitive sensor, a cover, and a moving mechanism. The photosensitive sensor includes a first lens and a second lens which focus on a photosensitive element. The cover includes a first slit arranged on an optical axis of the first lens and a second slit arranged on an optical axis of the second lens. The moving mechanism is configured to move the photosensitive sensor and the cover relative to each other so that the second slit is arranged on the optical axis of the first lens.

A shield plate that is used for non-contact measurement of a temperature of a measurement target is provided. The shield plate includes a base of which a temperature is adjustable. The base includes a central shield portion that is formed in the shield plate, an opening that is formed around the central shield portion, and a blackbody surface that is formed on one surface of the base to include a portion opposite to the opening with the central shield portion interposed therebetween and to radiate infrared rays.