Provided is a light emitting device that is bright in both scotopic vision and photopic vision, and has reduced glare for humans.

The light emitting device includes a light emitting element having a dominant wavelength in a range of 430 nm or more and 500 nm or less, and a fluorescent material that is excited by light emitted from the light emitting element and has a light emission peak wavelength in a range of 507 nm or more and 660 nm or less, wherein the light emitting device emits light having a dominant wavelength in a range of 490 nm or more and 500 nm or less, wherein the light emitting device has an S/P ratio, which is the ratio of a luminous flux in photopic vision to a luminous flux in scotopic vision, being 6.5 or less, and wherein the light emitting device has a light emission intensity in the light emission peak wavelength of the light emitting element that is greater than that in the light emission peak wavelength of the fluorescent material.

An object is to provide a new type of near-infrared ray-emitting phosphor which exhibits excellent emission intensity. A near-infrared ray-emitting phosphor is represented by a general formula, (Y, Lu, Gd).sub.3-x-y (Ga,Al,Sc).sub.5O.sub.12:(Cr.sub.x,(Yb,Nd).sub.y) (0.05<x<0.3, 0≤y<0.3).

A wavelength conversion module includes a base, a wavelength conversion member consisting of a phosphor, and a bonding member including a metal part that bonds the base and the wavelength conversion member. A thickness of the wavelength conversion member is less than 100 μm.

A process for detecting oil or lubricant contamination in the production of an article by adding a Stokes-shifting taggant to an oil or lubricant of a machine utilized to produce the article or a component thereof, irradiating the articles produced with a first wavelength of radiation, and monitoring the articles for emission of radiation at a second wavelength. The taggant can be in the form of a composition containing a Stokes-shifting taggant, which absorbs radiation at a first wavelength and emits radiation at a second wavelength, different from said first wavelength, dissolved or dispersed in an oil or lubricant.

A luminescent material can include a rare earth halide having a chemical formula of RE.sub.(1-A-B-C)HT.sub.ADET.sub.BSET.sub.CX.sub.z, wherein RE is a rare earth element, HT is an element or an interstitial site that provides a hole trap, DET is a dopant that provides a relatively deep electron trap, SET is a dopant that provides a relatively shallow electron trap, X is one or more halides, each of A, B, and C has a value greater at least 0.00001 and at most 0.09, and Z has a value in a range of 2 to 4. In an embodiment, a ratio of B:C is selected so that luminescent material has good linearity performance. In another embodiment, the ratio of B:C can be in a range of 10:1 to 100:1.

A luminescent material can include a rare earth halide having a chemical formula of RE.sub.(1-A-B-C)HT.sub.ADET.sub.BSET.sub.CX.sub.z, wherein RE is a rare earth element, HT is an element or an interstitial site that provides a hole trap, DET is a dopant that provides a relatively deep electron trap, SET is a dopant that provides a relatively shallow electron trap, X is one or more halides, each of A, B, and C has a value greater at least 0.00001 and at most 0.09, and Z has a value in a range of 2 to 4. In an embodiment, a ratio of B:C is selected so that luminescent material has good linearity performance. In another embodiment, the ratio of B:C can be in a range of 10:1 to 100:1.

A composition may include a base or matrix material, such as a resin, and a first optical brightener. The first optical brightener may include an alkaline earth metal compound and a fluorescence activator. The composition may include less than or equal to about 1.5 wt % of a second optical brightener relative to the weight of the composition, wherein the second optical brightener does not include the fluorescence activator. A composition may include an aqueous base and an optical brightener. The optical brightener may include an alkaline earth metal carbonate and a fluorescence activator, wherein the optical brightener is configured to emit fluorescent light. A composition may include a first optical brightener. The first optical brightener may include an alkaline earth compound, such as an alkaline earth metal salt, and a fluorescence activator, wherein, for a given brightness of a product including the composition, the composition including the first optical brightener may include less of a second optical brightener different from the first optical brightener.

A composition may include a base or matrix material, such as a resin, and a first optical brightener. The first optical brightener may include an alkaline earth metal compound and a fluorescence activator. The composition may include less than or equal to about 1.5 wt % of a second optical brightener relative to the weight of the composition, wherein the second optical brightener does not include the fluorescence activator. A composition may include an aqueous base and an optical brightener. The optical brightener may include an alkaline earth metal carbonate and a fluorescence activator, wherein the optical brightener is configured to emit fluorescent light. A composition may include a first optical brightener. The first optical brightener may include an alkaline earth compound, such as an alkaline earth metal salt, and a fluorescence activator, wherein, for a given brightness of a product including the composition, the composition including the first optical brightener may include less of a second optical brightener different from the first optical brightener.

A composition may include an aqueous base and at least one identifying additive. The at least one identifying additive may include an alkaline earth metal compound and a fluorescence activator. The at least one identifying additive may be configured such that the composition emits fluorescent light having an identifying characteristic different from a characteristic of a surface against which the identifying characteristic is viewed. A composition may include an aqueous base and at least one identifying additive including an alkaline earth metal compound and a fluorescence activator including at least one other inorganic element. The at least one identifying additive may be configured such that the composition emits fluorescent light having an identifying characteristic. A label or packaging for identifying at least one of an object and a source of the object may include a composition including at least one identifying additive associated with a surface associated with the label or packaging.

A composition may include an aqueous base and at least one identifying additive. The at least one identifying additive may include an alkaline earth metal compound and a fluorescence activator. The at least one identifying additive may be configured such that the composition emits fluorescent light having an identifying characteristic different from a characteristic of a surface against which the identifying characteristic is viewed. A composition may include an aqueous base and at least one identifying additive including an alkaline earth metal compound and a fluorescence activator including at least one other inorganic element. The at least one identifying additive may be configured such that the composition emits fluorescent light having an identifying characteristic. A label or packaging for identifying at least one of an object and a source of the object may include a composition including at least one identifying additive associated with a surface associated with the label or packaging.