"Express image" is translated from the Greek word: χαρακτήρ charakter (cha-rak-teer')
Do you know what it means?
HINT: No, you don't.
I do not have to know RD, I have translators that did that:
Hebrews 1:3
(ASV) who being the effulgence of his glory, and the very image of his substance, and upholding all things by the word of his power, when he had made purification of sins, sat down on the right hand of the Majesty on high;
(BBE) Who, being the outshining of his glory, the true image of his substance, supporting all things by the word of his power, having given himself as an offering making clean from sins, took his seat at the right hand of God in heaven;
(Bishops) Who beyng the bryghtnesse of the glorie, and the very image of his substaunce, vpholdyng all thynges with the worde of his power, hauing by him selfe pourged our sinnes, hath syt on the ryght hande of the maiestie on hye:
(CEV) God's Son has all the brightness of God's own glory and is like him in every way. By his own mighty word, he holds the universe together. After the Son had washed away our sins, he sat down at the right side of the glorious God in heaven.
(DRB) Who being the brightness of his glory and the figure of his substance and upholding all things by the word of his power, making purgation of sins, sitteth on the right hand of the majesty on high:
(ESV) He is the radiance of the glory of God and the exact imprint of his nature, and he upholds the universe by the word of his power. After making purification for sins, he sat down at the right hand of the Majesty on high,
(Geneva) Who being the brightnes of the glory, and the ingraued forme of his person, and bearing vp all things by his mightie worde, hath by himselfe purged our sinnes, and sitteth at the right hand of the Maiestie in the highest places,
(GNB) He reflects the brightness of God's glory and is the exact likeness of God's own being, sustaining the universe with his powerful word. After achieving forgiveness for the sins of all human beings, he sat down in heaven at the right side of God, the Supreme Power.
(GW) His Son is the reflection of God's glory and the exact likeness of God's being. He holds everything together through his powerful words. After he had cleansed people from their sins, he received the highest position, the one next to the Father in heaven.
(ISV) He is the reflection of God's glory and the exact likeness of his being, and he holds everything together by his powerful word. After he had provided a cleansing from sins, he sat down at the right hand of the Highest Majesty
(KJV) Who being the brightness of his glory, and the express image of his person, and upholding all things by the word of his power, when he had by himself purged our sins, sat down on the right hand of the Majesty on high;
(NAS77) And He is the radiance of His glory and the exact representation of His nature, and upholds all things by the word of His power. When He had made purification of sins, He sat down at the right hand of the Majesty on high;
(NASB) And He is the radiance of His glory and the exact representation of His nature, and upholds all things by the word of His power. When He had made purification of sins, He sat down at the right hand of the Majesty on high,
(NET.) The Son is the radiance of his glory and the representation of his essence, and he sustains all things by his powerful word, and so when he had accomplished cleansing for sins, he sat down at the right hand of the Majesty on high.
(NIrV) The Son is the gleaming brightness of God's glory. He is the exact likeness of God's being. He uses his powerful word to hold all things together. He provided the way for people to be made pure from sin. Then he sat down at the right hand of the King, the Majesty in heaven.
(NIV) The Son is the radiance of God's glory and the exact representation of his being, sustaining all things by his powerful word. After he had provided purification for sins, he sat down at the right hand of the Majesty in heaven.
(NKJV) who being the brightness of His glory and the express image of His person, and upholding all things by the word of His power, when He had by Himself purged our sins, sat down at the right hand of the Majesty on high,
(NRSV) He is the reflection of God's glory and the exact imprint of God's very being, and he sustains all things by his powerful word. When he had made purification for sins, he sat down at the right hand of the Majesty on high,
(NRSVA) He is the reflection of God's glory and the exact imprint of God's very being, and he sustains all things by his powerful word. When he had made purification for sins, he sat down at the right hand of the Majesty on high,
(TNIV) The Son is the radiance of God's glory and the exact representation of his being, sustaining all things by his powerful word. After he had provided purification for sins, he sat down at the right hand of the Majesty in heaven.
(YLT) who being the brightness of the glory, and the impress of His subsistence, bearing up also the all things by the saying of his might--through himself having made a cleansing of our sins, sat down at the right hand of the greatness in the highest,
When you stop thinking you know it all you may learn something.